Cables Facts and Figures

Revised 012008

Preview

This booklet has been revised several times to meet the demands of an ever-changing market, as well as specification changes as the result of improvingtechnology. It is not a treatise on electrical technology, but it is published to givesupplementary information to engineers, technicians and electricians involvedin cable selection and installation.

Aberdare hopes that users find it useful and invites any constructive (orcorrective) criticism.

PURPLE PEACH 09/2007

Aberdare Power Cables“with Compliments from Aberdare Cables”

1.0 How to Select a Cable

2.0 Useful Electrical Formulae

3.0 Transport, Handling and Installation of Electric Cables

1.1 Load to be supplied1.2 Permissible Voltage Drop1.3 Prospective Fault Current1.4 Environmental Conditions of Installation1.4.1 Cables Laid Direct in the Ground1.4.2 Cables Installed in Air1.4.3 Cables installed in Ducts1.4.4 Composite Cable Routes1.4.5 Intermittent Operation1.4.6 Solar Heating

2.1 Volt Drop2.2 Charging Current2.3 Per Unit System2.4 Load Growth2.5 Load Factor2.6 Capacitor Voltage Rise2.7 Load Sharing2.8 Conductor Resistance2.9 Lead Resistance2.10 Wire Armour Resistance

3.1 Cables on Wooden Drums3.2 Cable Transportation3.3 Cable Storage3.4 Mechanical Forces on Cables during Installation3.5 Pulling Cables through Pipes or Ducts3.6 Preparation for Cable Laying3.7 Backfilling and Reinstatement3.8 Repairs to PVC Oversheaths

1

12

16

115789

10101011

12131313131314141515

1617181819202626

Contents

4.0 Paper Insulated and Lead Covered 6.35/11kV Cables

5.0 Medium Voltage XLPE Insulated, PVC Bedded, SWA,

PVC sheathed 6.35/11kV Cables

6.0 Low Voltage PVC and XLPE insulated 600/1000V

Power Cables

7.0 ElastomericTrailing Cables

8.0 Overhead Aluminium Conductors

9.0 Innovative products

4.1 Notes on impregnating compound4.2 Moisture in Paper cables4.3 Derating factors for non-standard conditions4.4 Short circuit ratings for PILC cables4.5 Earth fault ratings

5.1 Notes on XLPE insulation5.2 Derating factors for non-standard conditions5.3 Short circuit ratings for XLPE insulated 6.35/11kV

cables5.4 Earth fault current

6.1 Notes on PVC and XLPE insulation6.2 Cable cross section6.3 Derating factors for non-standard conditions6.4 Short circuit ratings for PVC and XLPE insulated

600/1000V cables

- INTERDAC 3

ContentsContinuation ...

27

32

37

46

50

52

2727293031

323435

36

373744

46

1.0 How to Select a Cable

1.1 Load to be supplied

The following formulae apply:

1.2 PermissibleVoltage Drop

When selecting a cable for your specific application, a number of variablesrequire attention.These are:(a) Size and type of load to be supplied(b) Permissible voltage drop(c) Prospective fault current(d) Circuit protection(e) Environmental conditions of installation

In order to select the appropriate cable, it is necessary to know the voltageand the load current in amps. This information will be available eitherdirectly in amps or as kW or kVA.

= x 1000 Amps3 xV x Cos

Amps

Use this value of current to determine the cable size by reference to therelevant tables given in Section 4 (Paper insulated), Section 5 (XLPE insu-lated medium voltage) or Section 6 (PVC and XLPE insulated low voltage)for Copper or Aluminium conductors.

A slightly larger conductor size may be chosen for safety aspects, and toprovide for the higher than usual current which may be experienced duringstarting of electric motors.

Suppose it is required to supply a 3 phase, 400 volt, 100kW motor con-nected in star/delta, over a distance of 50m buried direct in ground. Themotor load is known to have a power factor of 0,9 lagging. The full load linecurrent, IFL can be calculated as follows:

We now refer to table 6.2 on pg 38 and note that the smallest copperconductor, PVC insulated cable, that can supply a current of 161 amps inthe ground, is a 50 mm² rated area cable. This cable can carry 169 ampscontinuously if installed under standard conditions.

Calculate the highest current drawn by the load, by multiplying the currentas calculated in 1.1 by an appropriate factor. If a Star/Delta motor starter isused on a motor, this factor is 3. If the motor is started direct on line, thenuse a factor of 6. Where the load is resistive heating, lighting or atransformer, it is not necessary to increase the current as calculated in 1.1.

IFL kW if we know kW, voltage, as well as power factor

if we know the kVA rating as well as the voltage

f

I

I

FL = x 10003 xV

= 100 x 10003 x 400 x 0,9

= 161 Amps

kVA

Example of Cable Selection for LowVoltage

FL

1

Calculate the volt drop which will be experienced at the load terminals byreference to table 6.2 or 6.3 on pg 38 or pg 39. The maximum volt dropallowed by SANS 10142-1 during full load running condition. There is nohard and fast rule as to the allowable volt drop under starting conditions.Depending on the type of load to be started, there is the possibility that thetorque may be compromised during starting, if the motor is subjected todifficult starting conditions. A reasonable volt drop should be chosen inthese cases

The volt drop may be calculated in two different ways:

Using Method (b)

Note:

(a) Multiplying the current by the impedance of the length of cable.Calculate the percentage volt drop by reference to the phase to earthvoltage.

(b) Multiply the current by the length of cable, and then multiply the resultby the volt drop per amp per metre figure as given in table 6.2 or 6.3 onpage 38 or page 39, depending on the type of conductor.

Starting Current = 3 x Running Current= 3 x 161 Amps= 483 Amps

Impedance of 50m of 50mm² Cable (Table 6.2) pg 38= 0,4718 x 50

1000= 0,02359 ohms

Volt Drop = 483 x 0,02359= 11,394 x 100

230 1= 4,95% (Acceptable)

Starting Current = 3 x 161 Amps= 483 Amps

Volt Drop per amp per metre = 0,817 mV/A/m (Table 6.2) pg 38Volt Drop = 0,817 x 10 x 483 x 50

= 19,73 voltsPercentageVolt Drop = 19,73 x 100

400 1= 4,93% (Acceptable)

It often happens on long runs of electric cable that a larger conductorthan that calculated in 1.1 is required for volt drop reasons.

Previous example using method (a)

-3

2

Example of Cable Selection for MediumVoltage (11kV)We wish to supply a 2MVA 11kV transformer from an Eskom supply pointwhich is 3km away. We are to use an underground paper insulated, copperconductor cable. The depth of burial of the cable is 1,25m. Ground thermalresistivity is 2K.m/W. The ground temperature is 25°C and there are noother cables in the trench.

Short circuit level may be assumed to be 250 MVA, and the earth fault level100 MVA, and it may be assumed that a fault will be cleared in half asecond.

= 2 000 0003 x 11 000

= 105 Amps before derating for nonstandard conditions

Derating factor for Depth of Burial at 1,25 m is 0,96.Derating factor for SoilThermal Resistivity at 2 K.m/W is 0,84.Derating factor for GroundTemperature of 25°C is 1,00.

Total Derating = 0,96 x 0,84 x 1,00

= 0,8064

Standard = 1050,8064

= 130 Amps

Table 4.2 on pg 28 shows that a 35 mm² Copper conductor cable would becapable of carrying this load (130A). This is confirmed by reference to thePaper Insulated Cable brochure (Page 13).

The cable size required is thus 35 mm² Copper conductor, 3 Core Generalpurpose belted cable. (Table 17 SANS 97).

Volt Drop = Z x 3 x x distance1000

= 0,6371 x 1,73 x 105 x 30001000

= 347,6 volts (3,2% of 11kV)

Volt drop is seldom a problem at Medium Voltage, even for long runs ofsmall conductor size as shown above.

Using the previous formulae:

Checking for volt drop:

I

I

FL

3

Prospective Symmetrical (Short Circuit) Current= 250 000 000

3 x 11 000

= 13,122 kA

= Cross Section x Kt

K is 115A/mm² for copper conductors, paper insulated.

0,5

Checking for fault current

Cable short circuit current with stand is

Isc

35 x 115 = 5,692 kA0,5

This cable will not survive the prospective short circuit current.

x 115 = 13,122 kA

= 80 mm²

Nearest standard size is a 95 mm² Copper conductor.This has a current rating of 235 Amps under standard conditions.

Lead area for a 95 mm² x 3 Core PILC cable is approximately 200 mm²

= 200 x 0,0240,5

= 6,8 kA for half a second

= 100 000 0003 x 11 000

= 5,25 kA for half a second

In many cases, the cable conductor size is larger than dictated by the fullload current, and is chosen in order to survive the prospective short circuitcurrent. The use of large conductors can be avoided by improving thespeed of protection, (fuses for example) and in the case of earth faultcurrent, by the use of sensitive earth fault protection.

The half second rating is thus:

Conductor size required is thus:

Earth fault current for half a second:

Cable earth fault current withstand is:

Required earth fault current:

x

\x

IEF

4

5

1.3 Prospective Fault CurrentElectric cables are designed to operate below a certain maximum temp-erature, this being dependent on the conductor material and the type andthe thickness of the insulation.

Cable selection for a particular installation must therefore be made on thebasis of not exceeding these temperature limits.

Suppose the 400 volt distribution board from which a cable is fed has a faultlevel of 5 MVA. This translates to a fault current of 7,22 kA, and the cablemust be capable of passing this current without damage until the fault iscleared.

The smallest cable that can safely handle this fault current for a 1 secondfault, is a 70 mm² copper conductor cable, or a 95 mm² aluminiumconductor cable. Suppose now that the fault clearance time (including anymechanical delays on the tripping mechanism) is closer to 2 seconds, thenthe smallest cable would be a 95 mm² copper conductor(10,925 ÷ 2=7,725 kA for 2 seconds) or a 150 mm² aluminium conductor (11,400 ÷ 2 =8,061kA for 2 seconds). Likewise, a fault duration less than 1 second willallow the use of smaller conductors than were calculated for the1secondrating.

impedance

Consider the following diagram:Diagrammatically, the system is:-

p.u. source = Base MVAFault Level MVA

p.u. transformer = Base MVA x Transformers % Impedanceimpedance Transformer MVA

p.u. cable = Z (ohms) x Base MVAimpedance V (kV)

(1) + (2) + (3) = p.u. impedance

Another Example:

We are required to calculate the fault current at the sub dist board.

P.U. SYSTEM

(1)

(2)

(3)2

11kV

11kVRing

FaultLevel250MVA

Main LV Dis Board

Sub Dis Board

TRANSFORMER

Board500 kVA

Z=0,05 p.u.

100 metres50 metres 100kW Motor185mm² Copper

Cable 70mm² CopperCable

Pf 0.9

/

X

X

X X

X

X

X

Fault Level = Base MVA MVAp.u. impedance

Fault Current = Fault Level (MVA) x 1 000 0003 x Voltage (V)

Source 100 = 0,4 p.u.250

Transformer 100 x 0,05 = 10 p.u.0,5

Example 1: Using a base of 100 MVA and the per unit method, theimpedance of the system at the sub-dist board can be determined:

FromTable 6.2 on pg 38 the impedance of 185 mm² cable = 0,1445 /kmThus the impedance of 100 m = 0,01445

Z.p.u. = Z (ohms) c MVA = 0,01445 x 100 = 9,03 p.u.V2 (kV) (0,400)2

Fault Level at Sub Board = 100 = 5,147 MVA0,4 + 10 + 9,03

Fault Current at = 5,147 x 1 000 000 = 7,429 kASub-Dist Board 3 x 400

Source 250 = 1 p.u.250

Transformer 250 x 0,05 = 25 p.u.0,5

Cable 0,01445 x 250 = 22,578 p.u.(0,400)2

Total Impedance = 48,578

Fault Level = 250 = 5,146 MVA48,578

Fault Current = 5,146 x 1 000 0003 x 400

= 7,428 kA

WW

The fault level at the sub-dist board is then found by dividing the baseMVA by the total per unit impedance:

Example 2: Using a Base of 250 MVA, the same result is obtained:

6

From the above illustration, it is clear that whatever may be the value ofBase MVA, short circuit current is the same. However, in the interest ofsimplicity a numerical convenient value of the Base MVA should bechosen.

Where k = 115A/mm² for PVC / Copper cables, shows that a 70 mm²copper cable can withstand a short circuit current of 8.05 kA for 1 second.This is above the potential fault level of the system. Moreover, the durationof the fault or the time taken by the protective device to operate has to beconsidered.The circuit supplying the motor would very likely be protectedby a 200 amp fuse or a circuit breaker. Both these devices would operatewell within 1 second, the actual time being read from the curves showingshort circuit current / tripping time relationships supplied by the protectiveequipment manufacturer. Suppose the fault is cleared after 0,2 seconds.We need to determine what short circuit current the cable can withstandfor this time

This can be found from the expression = A x Kt

and where A is the conductor cross sectional area in mm² and t the durationof the fault in seconds

So in our example = 70 x 115 = 18 kA0,2

This is well in excess of the system potential fault level and so it can beconcluded that a 70 mm² cable is suitable for this example. During theperiod of short circuits, the forces acting upon individual cores of a 3 phasesystem are enormous. These are forces of repulsion and attraction, andhence cause the cores to move if inadequately restrained. In the case of 3core armoured cables, the fact that the cores are laid up, and therestraining effect of the armour wires is such as to limit the coremovement. Bursting strengths are, however, still important in the case ofPILC cables where the effect of the resultant voids left in the insulation(even after small movement) may be detrimental to the long term life of thecable so affected.

The data used for determining the current ratings given in this publicationare based on calculations according to IEC 287. Ratings for multicorecables are given for a single cable run. Where groups of cables run in acommon route the appropriate derating factors are given in the tables onpages 29 ; 34 and 44 depending on the type of cable being used.

Similarly when the installation conditions differ from standard, the deratingfactors in the appropriate sections must be used.

I

I

sc

sc

where K = 115 for PVC / Copper cables (70°C - 160°C)K = 143 for XLPE / Copper cablesK =76 for PVC / Aluminum (solid or stranded) cables (70°C - 160°C)K = 92 for XLPE / Aluminum (solid or stranded) cablesK = 115 for PILC / Copper cables (70°C - 160°C)K = 76 for PILC / Aluminum (stranded) cables (70°C - 160°C)

(90°C - 250°C)

(90°C - 250°C)

1.4 Environmental Conditions of Installation

7

A qualitative assessment of the conditions immediately surrounding thecable should be made. Factors such as the need for a fire retardantsheath, additional mechanical protection, safeguards against chemicalattack and corrosion should be considered in this category. Theseinfluences affect mainly the external finish of the cable, the armouringand serving.

Cables are sometimes specified with a termite repellent sheath. It isworth mentioning that no sheath will repel insects since sheath materialhas to be ingested by the termite to be fatal. Thus, the statement ‘cablewith a termite repellant sheath’ is somewhat erroneous.

In the case of paper lead cables there are several alternative sheathmetals available, pure lead is prone to fatigue when subjected tovibration. Alloy E sheath can be supplied which will resist deteriorationthrough fatigue.

The foregoing notes are by no means an exhaustive treatment of thepoints to consider when choosing a cable for a particular application butare ratherguidelines to the salient points which need consideration.

1.4.1 Cables Laid Direct in the Ground

Suitability of soils for bedding and backfill

Clay:

Sand:

Sand clay:

The ratings given are based on a ground thermal resistivity (g) of 1,2K.m/W. The factor (g), varies considerably with differing groundconditions and has a pronounced effect on a cable’s current carryingcapacity. The only sure way to determine (g) is to measure it along thecable route. This practice is normally reserved for supertension cables,but there could be other applications where soil thermal resistivity iscritical.

Clay is a dense, compact material, greasy to the touch when wetand which has a low Thermal Resistivity even in the fully dried-outcondition. Most clays however, shrink when drying and can thus not beused as a bedding for the cable. They can be used as backfill and shouldbe consolidated by rolling rather than tamping.

Sand is a crumbly material with particle grains easily distinguishedand gritty to the touch even when wet. Particle sizes larger than 2mm areknown as gravel. Sea sand or sand obtained from a river bed usuallyconsists of spherical particles and has a very high Thermal Resistivitywhen dry. Some quarried sands and man-made sands as used formaking concrete, have irregularly shaped particles of varying size andcan be compacted to a high density. These can be used as a beddingmaterial especially when 5-10% clay is added and will have asatisfactorily low Thermal Resistivity in the dried-out state. Sand/gravelmixes should be used with care as sharp particles can damage the cableserving.

Sand clay is, as its name implies, a mixture of sand and clay.It is an ideal material for use as bedding and backfill and is bestcompacted by rolling. It rarely dries out to lower than 6% moisturecontent.

8

9

Loam:

Chalk:

Ouklip:

Peat:

Loam can vary in colour from reddish brown to dark brown andmay contain quantities of organic matter. It crumbles well, even whendry, and can be well compacted to achieve satisfactory values ofThermalResistivity. It is very suitable as a bedding material.

Chalk is a soft white or grey porous material having a lowerThermal Resistivity when wet, but drying out to very high values and isunsuitable for use as bedding or backfill in any area where drying out islikely.

Ouklip is decomposed rocky material, varying in particle size andhaving very low Thermal Resistivity in the undisturbed state. It can beused as a backfill material when mixed with loam or clay but should notbe used as a cable bedding.

Peat or humus is composed mainly of organic material and is blackor dark brown in colour. It should not be used as bedding or backfill asdried-out Thermal Resistivity values of over 4 K.m/W are usuallyobtained. It should be removed and alternative material used for bothbedding the cables and backfilling the trench.

Make-up soil:

Mine sand:

This is a general term for the soil in any area, the level ofwhich has been raised artificially using imported fill which may consist ofbricks, concrete, cinders, ash, slag, stones, other refuse or any of thematerial considered above. If any doubt exists as to suitability, it is bestremoved completely and a suitable material imported.

Mine sand is thermally very satisfactory, but is highlycorrosive and should therefore not be used.

Material

Sandy Soil

Clay

Chalky Soil

Concrete

Water logged ground

Gravel

1,20

1,60

1,80

0,90

0,50

1,00

Thermal Resistivity (g) K.m/W

Table 1.1

The thermal resistivity of a substance is greatly influenced by themoisture content at a given time. The higher the quantity of retainedmoisture the lower will be the thermal resistivity. A heavily loaded cablewill dry out the soil around the cable and cause an increase in (g). Thisprocess is cumulative and damage could be done to the cable insulationthrough over-heating.

Impurities such as slag, ash and the like increase the value of (g), as doesintense vegetation on the cable route, by drawing moisture from theground.

Multicore cables should be installed with a space of 0,3 x overall1.4.2 Cables Installed inAir

>

10

diameter and single core cables with a space of 0,5 x overalldiameter between themselves and the vertical wall or surface sup-porting them as per IEC 287 If they are installed in direct contact withthe wall then the current rating given should be reduced by 5% as arough guide line provided there is a space of 150mm or six times theoverall diameter of the cable whichever is the greater between adjacentcables or cable groups in the case of single core cables. If the installationfails to comply with this requirement then the derating factors in therelevant sections should be applied.

Where the ambient temperature along a route varies, the highest valueshould be taken to select the cable size.

The air within a pipe or duct will increase the thermal resistance of theheat dissipation path. Consequently the current rating or a cable run in aduct (pipe) is lower than that for an equivalent cable in the ground or infree air. The ratings given can be applied to cables laid in concrete,asbestos,

>

1.4.3 Cables Installed in Ducts

pitch fibre, PVC, earthenware or cast iron pipes which are the morecommon materials encountered. It should be noted that single corecables forming a part of an a.c. system should not be individuallyinstalled in cast iron pipes due to the heavy losses incurred by eddycurrent induction.

Generally the size of the duct (pipe) chosen should depend upon theease of pulling in, or out, the cable. It should be borne in mind that alarger cable may be required in the future to cater for increased loadgrowth. Common pipe sizes used in South Africa are 100mm and150mm internal diameters. When groups of cables are run in pipesalong the same route, they should be derated according to the factorsgiven in the relevant tables.

It frequently happens that a cable run is made partly in air, partly direct inthe ground and partly in ducts. The latter conditions lead to the lowestrating and it is here that attention must be focused. Very little heattravels longitudinally along the cable, the main dissipation being verti-cally through the duct wall and surrounding ground. Any rating where theroute is part ground, part duct must therefore be treated with care.

Where the length of ducting does not exceed 5 metres per 100m ofroute length, the cable rating may be assumed to be that for direct burialin the ground.

Certain types of loads have an intermittent characteristic where the loadis switched on and off before the cable has time to cool completely.Depending upon the load cycle it may be possible to select a smallercable for intermittent operation than would be the case if the load werecontinuously applied. When a current in excess of the normal ratedcurrent is applied, the heating of the cable will be a correspondinglyquicker operation than the cooling.

1.4.4 Composite Cable Routes

1.4.5 Intermittent Operation

Thus a continuous current of 76 amps flowing over the 10 minute cycletime would produce the same heating effect as the individual cycliccurrents, and the size of cable could be selected based on 76 amps.

When cables are installed in direct sunlight, an appreciable heating dueto solar absorption takes place. This results in a significant reduction inthe cables current carrying capacity and for this reason it is stronglyrecommended that cables be protected from direct sunlight. Themaximum intensity of solar radiation measured in South Africa variesbetween 1000 and 1250 /m² depending upon location.

1.4.6 Solar Heating

W

11

Thus

( )²tIn n

n = N

n = 1n = N

n = 1

( )tn

I =

( )²tIn n

n = N

n = 1n = N

n = 1

(t )n

I =

57 50010

=

= 75,83 Amps

• 150 Amps for 1 minute • 50 Amps for 2 minutes• 100 Amps for 3 minutes • 0 Amps for 4 minutes

Then applying the expression for RMS current.

ExampleSuppose a process cycle is as follow:

Generally = Equivalent RMS current= Current flowing during th period (Including

periods of zero current).t = Duration of nth periodN = Number of periods, (includes periods of zero

current)

I

In n

n

2.0 Useful Electrical Formulae

2.1 Volt Drop

The voltage drop in a single phase circuit is given by:Volt Drop = 2 x ( cos x sin )

Induction Reactance X = 2 fL ohms

Capacitive Reactance X = 12 fC

Where a, b and c are the distance in mm between the centres of the threephases conductors.

X I R

where I = Line current ampsR = Circuit resistance ohms/phaseX = Circuit reactance ohms/phase

= Angle of lead or lag between current andvoltage

where f = supply frequency HertzL = circuit inductance HenrysC = circuit capacitance Farads

+f f

w

w p

f

p

Î m

Î

f

p

p

L

C

Impedance Z = R + ( L) ohms

Power Factor cos = RZ

Admittance Y = G-jB ohms

Capacitive Susceptance B = 2 fC (Siemens)

L = 0,0516 + 0,46 log mH/km/phaser

C = 0,024 l r F/km/phaselog

r

GMD = abc

2 2

3

Where = 2 f

Where G = conductance (Siemens)B = susceptance (Siemens)

GMD

andGMD

where GMD = Geometric mean diameter mmr = Conductor radius mmr = Relative permittivity of dielectric

For a 3 Core Screened Underground Cable or Overhead Line:

12

13

2.2 Charging Current

2.3 Per Unit System

2.4 Load Growth

2.5 Load Factor

2.6 CapacitorVoltage Rise

Charging current = 2 f amps/km3 x 10

In the case of an underground cable with shaped conductors, C is increa-sed by 8%.

Per unit impedance Z = x Z (ohms)E

Per unit impedance referred to a given base MVA

= Actual Z p.u. x Base MVAFull Load MVA

Z p.u. on given MVA base

= MVA Base x Z (ohms)E

Load growth L in n year at (g) % per annum

Ln = Lo (1 + ) MW

where Lo = Load in first year in MW.

Monthly Load Factor = kWh Sold per MonthNumber of Hours per Month x M.D. kW

Monthly Diversity Factor =Individual Consumers M.D.’s

Per unit voltage rise in a circuit due to capacitorsV p.u. =

3 Phase Capacitor kVAR3 Phase Fault Level kVA

p

m

C E

where C = Capacitance per phase FE = Line to line voltage

6

2

th

n

I

SSimultaneous M.D. Recorded during the Month

g100

14

2.7 Load Sharing

2.8 Conductor Resistance

Natural load sharing between 2 parallel feeders

= Amps+

= Amps+

+

Change of conductor resistance with temperature

= (1 + (T -T ) ohms

The a.c. resistance of a conductor is given by:

= R (1+ + )

I I

I I

I I I

1 2 2

1 1 2 2

2 1 1

1 1 2 2

t o t o

t

o

a d 1

d

1

ZZ Z

ZZ Z

where == Angle of load current= Angle of transmission line 1= Angle of transmission line 2

R R

where R = d.c. resistance at temperatureT °CR = Initial d.c. resistance at temperatureT °C

= Temperature co-efficient of resistance ofconductor material

R y y

where R = d.c. resistancey = skin effect factory = proximity effect factor

Ðq ÐfÐq Ðq

Ðq ÐfÐq Ðq

fqq

a

a

1 2

1

2

t

t

[ ]

(1 + + )y y1

3 Core

Up to 185

240

300

400

500

630

800

1000

1,027

1,041

1,068

1,115

1,175

-

-

-

1,019

1,027

1,048

1,087

1,136

1,208

1,315

1,516

Single Core

Conductor Area

mm²

Table 2.1 : Values of (1 + + ) for 1000 volt cablesy y1

2.9 Lead Resistance

2.10 WireArmour Resistance

Resistance = 238,1 ohms/kmarea of PipeWall

Resistance = 185,03 ohms/kmd N

where d = wire diameterN = Number of wires

2

Volume Resistivity ohm/mm²/km

Specific Gravity

Temperature co-efficient of Resistance per °CCo-efficient of linear Expansion per C

Specific Heat cals/g

Melting Point C

°

°

Copper Annealed

17,2414

8,89

3,93 x 10

17 x 10

0,093

1065

-3

-6

Aluminium Annealed

28,03

2,703

4,03 x 10

23 x 10

0,24

659

-3

-6

Property

15

Table 2.2 : Characteristics of Copper and Aluminium conductors

It can be shown that aluminium has 78% of the current carrying capacity ofan equivalent size copper conductor. The current rating of a cable dependsupon the thermal dissipation of the conductor I²R losses. Using thesuffixes ‘c’ for copper and ‘a’ for aluminium, equal conductor losses aresatisfied by:

x R = x R

= R xR

= 17,2414 x28,03

= 0,61 x

= 0,61 x

= 0,78

I I

I I

I

I

I I

I

c2

c a2

a

a2

c c2

a

c2

c2

a c

c

16

3.0 Transport, Handling and Installation of Electric Cables

3.1 Cables onWooden Drums

Figure 1

(a) The cable drum is manufactured from carefully selected locally grownwood with a low moisture content (typical not more than 15%) (Fig. 1)if they are required to be treated it shall be done in accordance withSANS 05 with a Class C preservative or with chromate copperarsenate. Saligna, which is a hardwood, does not require treatment.

(b) Marking on drum flanges should be clear, stencilled or burned into thewood and should include the following information:

(i) Manufacturer’s name or trade mark.(ii) Rated voltage, rated area, number of cores and specification.(iii) Length of the cable in metres.(iv) Year of manufacture.(v) Gross mass in kilograms.(vi) The instruction“NOTTO BE LAID FLAT”.(vii) Serial number or other identification.(viii) On each flange an arrow with the words“ROLLTHISWAY”.(ix) SABS Mark (if applicable).

(c) Both ends of the cables on the drum should be sealed and the innerend fixed to the flange of the cable drum to prevent loose coiling. Theouter end is fixed to the flange as well, for the same reason.

(d) Cable drums should stand on firm, well-drained surfaces.

(e) In the past, it was common practice to rotate stored cable drumsthrough 180° to re-distribute the rosin impregnation oil through thedielectric. The use of MIND cables has obviated this reason forrotating drums. However, it is still recommended that wooden cabledrums that are stored in the open, irrespective of the type of cablecontained, should be periodically rotated to avoid the drum timberrotting through rising damp.

98-1999

163010 063

MASS E894 KG

rollthisway

CP 11/6

3.2 CableTransportation

Preparation

Figure 2

Loading

Securing

Off loading

(a)(i) The truck must match the drum size.(ii) Do not overload the trucks.(iii) Cable ends must be sealed, secured and protected(iv) Use special cable trailers for depot to site transportation if

possible (See fig. 2).

(b)(i) Check drums for correct cable and size, serial number, mass

and possible damage.(ii) Select correct forklift/crane.(iii) Select correct slings and spindle and check sling condition.(iv) If a crane is to be used, ensure that a spreader is incorporated

to prevent damage to drum flanges.(v) If the drum is to be rolled, observe correct rolling direction by

referring to arrows on flanges.(vi) Ensure that the drum bolts are tight.(vii) Ensure that truck surface is clear of obstructions, nails etc.(viii) Do not drop drums onto truck loading bed.

(c)(i) Secure drums to the truck bed to prevent sliding and rolling,

using adequate steel chains and chocks.(ii) Always try to pack drums flange-to-flange.(iii) Do not lay drums flat.(iv) Stop the vehicle during transportation and check that the load

is secure.

(d)(i) Check for damage to cable drums.(ii) Select correct spindle slings for the drum size and mass and

ensure that same are in good order, ensure that a spreader isused.

(iii) Do not drop drums but lower gently onto firm and relativelylevel surfaces.

(iv) Off load drums in such a way that they are easily accessible.(v) If using a fork-truck, ensure that it is of adequate size relative to

the task at hand.(vi) Ensure that the fork-truck tyres lateral spacing is correct.(vii) Take care that the protruding tyres do not damage other

equipment or drums.(viii) There are two methods of rolling drums from loading beds if

cranes are not available (See fig.3)

Cable Trailer

17

18

Figure 3

Method 1:

Method 2

3.3 Cable storage

Indoors

Outdoors

3.4 Mechanical Forces on Cables during Installation

Hole excavated maximum slope 1 in 10 to receive

: Ramp constructed maximum slope 1 in 4

(a)(i) Stack flange-to-flange and preferably not one on top of the

other.(ii) Stack so that drums are easily accessible.(iii) Observe fire prevention rules.(iv) Cable ends must be sealed at all times.(v) Despatch on“first in - first out” basis.(vi) Rotate Paper insulated cable drums one complete revolution

per annum.

(b)(i) Drums should stored on a hard surface at a slight angle and the

area should(ii) Drums should be released on a“first in - first out” basis.(iii) Cable ends should be sealed at all times.(iv) Stack flange-to-flange but if this is not possible limit vertical

stacking practice to smaller drums only.(v) Stack in such a way that drums are easily accessible.(vi) Observe fire protection rules.(vii) Cable racks are ideal for storage but take care not to overload.(viii) Cables must be identifiable at all times.(ix) If drums are expected to be stored for a long time they must be

specially treated or made of hard wood.(x) Rotate Paper insulated cable drums one complete revolution

per annum.

Any cable has a maximum pulling force which should not be exceededduring installation. The cable construction imposes the limitation on thepulling-in force. When a cable stocking is used the maximum force can berelated to overall cable diameter in mm as follows:

have a drainage system.

Drum stop

19

SteelWire Armoured Cables F = 0.94 d x 10 kN

Attempts should be made to limit the pulling force required to a minimumto avoid stretching the outer layers of the cable. This is particularly relevantwhere control and communication cables are concerned since instancesare known where the cores have finished 2-3 metres inside the sheath andinsufficient overlap at straight joint positions has necessitated re-layingsome lengths.

An increase in the pulling force is permissible when the cable is laid bymeans of a pulling eye attached to the conductors. As a rule of thumb, thefollowing forces may be applied to a conductor:-

Copper 4.9 x 10 kN/mm²

Then, for example the maximum force that should be applied via a pullingeye to a 70mm² 3 core copper cable is:-

70 x 3 x 4.9 x 10 = 10.29 kN

Generally when cables are installed using well-oiled rollers and jacks, thefollowing forces can be expected:-

straight route15 - 20% of cable weight2 - 90° bends 20 - 40% of cable weight

Cables laid in open trenches should be left slightly “snaked” so that anylongitudinal expansion or contraction can be accommodated. Similarlywhen cables are installed in cleats or on hangers a slight sag betweenfixing points is recommended.

When a cable is pulled through a pipe, friction between the cable servingand the pipe material increases the longitudinal force requirements.Representative values for the co-efficient of friction ( ) between the morecommon cable servings and pipe materials are given below:-

4 -6

-2

SteelTape Armoured or Unarmoured Cable F = 0.39 d x 10 kNControl and Communication Cables F = 0.26 d x 10 kN

Aluminium 2.94 x 10 kN/mm²

4 -6

4 -6

-2

-2

3.5 Pulling cables through Pipes or Ducts

m

Table 3.1

Serving Material Pipe Material

PVC

PVC

PVC

PVC

Bitumenized

Hessian

or Jute

Asbestos

Metal (Steel)

Pitch Fibre

PVC

Asbestos

Metal (Steel)

Pitch Fibre

PVC

0,65

0,48

0,55

0,35

0,97

0,76

0,86

0,55

20

This information can readily be used to determine the maximum length ofcable that can be pulled through a given pipe without exceeding themaximum permissible pulling force. Take for example the 70 mm² x 3 corecable previously quoted, if this is a low voltage cable with a PVC sheath andit is desired to know the maximum length of PVC pipe it can be pulledthrough then:-

Maximum force = 10.29 kN (by pulling eye)for PVC to PVC = 0.35But force = x Reactive force

= x Cable weight= x Cable mass

102

mass of cable = 10.29 x 102 = 2 998 kg0,35(1 kN = 102 kg)

From the table the mass of 70 mm² x 3 Core copper cable is 3,6 kg/m.

Thus the maximum length of cable that can be pulled through a PVC pipe is:

2 998 = 832 metres3,6

If there are any bends in the route then these will create additional loadingand reduce the theoretical length of cable that can be installed.

In certain instances when long runs in pipes or ducts are encountered itmay be beneficial to grease the cable with petroleum jelly or some othernon aggressive compound to facilitate the pulling-in.

Considerable damage can be done to cable serving at the mouth of a pipeand precautions should be exercised at such points. This point is achievingmore importance with the present day trend towards impermeable anticorrosive sheaths which have to withstand periodic pressure tests.Included among the protective measures that can be adopted are thefitting of a rubber grommet to the mouth of the pipe and inserting areasonable thickness of rag.

When unarmoured cables are pulled into pipes it will be beneficial toensure that there is no foreign matter present which could cause damageto the sheath before pulling. Pushing a draw rod through the pipe willusually clear any obstruction.

mmm

3.6 Preparation for Cable Laying

Planning(a)When planning a cable route there are several factors to beconsidered, among the most important of these are:

(i) GroundThermal resistivity (TR) tests.(ii) Position of joint bays.(iii) Provision to indicate on the ‘as laid’ drawings, the serial or

drum number of the cable installed.

(iv) The use of mass or pre-impregnated non-draining Paperinsulated cables, XLPE and PVC dielectrics has all buteliminated the need for special precautions when layingcables on steep slopes in shafts.

(b)

(i) Always use the best hoisting equipment available.

(ii) Do not drop drums of cable onto the ground as this not onlydamages the drum but will damage the cable as well(especially Paper insulated cable).

(iii) It is most important that a minimum of rolling of the drums onthe ground be allowed and then only in the direction of thearrows painted on the flanges.

(iv) When rolling a drum of cable, to change direction use 2 steelplates with grease between them, and by standing one flangeon these plates the cable drum may then be swivelled in thedesired direction.

(v) Position the drum prior to cable-pulling so that the cable ispulled from the top of the drum.

(vi) Note that a drum of power cable can weigh up to 10 tons somake sure that adequate cable drum jacks are used, that thespindle is strong enough to hold the drum and that the jacksstand on firm ground and that they hold the spindle horizontal.

(vii) Site the drum at the most convenient place for cable-pulling,usually at the start of a reasonably straight section near thecommencement of the trench work.

(viii) Allow for drum braking.

( c)

(i) This often governs the rating of a power cable buried directly, asdoes the temperature of the soil. Losses for cables running atthe maximum temperature at which the dielectric system canfaithfully operate for a maximum life of say, 25 years, areconsiderable, ranging from 15 W/m for normal distributioncables. Cable conductor temperature and the soil surroundingthe cable must be able to dissipate this heat effectively orthermal instability (runaway)will result. For example an XLPEinsulated 11 kV cable with conductors running at 90°C could endup with a surface temperature of about 80°C resulting in drying-out of the soil. Depth of burial plays an important factor here andhas been set at 800 mm. Most MV Cable current ratings arecalculated with ground temperatures at 25°C at depths of burialof 800 mm.

Drum Handling

GroundThermal Resistivity

21

22

LV cables are normally buried at 500 mm. Soil thermal resis-tivity (the ability of the soil to conduct or dissipate heat) isstandard at 1.2K.m/W.

(ii) The actual soil thermal resistivity along the proposed routeshould be measured either by means of an ERA needle probeor the SABS needle probe, but these are outside the scope ofthis paper, suffice it to say that different soil compositionsalong the route will have different rates of heat dissipation andcould result in“hot spots”.

(iii) To overcome this, bedding and backfill soils may have to be“imported”.

(d)

Ensure that there is sufficient working space, consider passing trafficand other obstructions. If it is not possible to position the joint bays atstandard cable length distances, remember that the cable can beordered in specific lengths. Consider drainage for large bays and tryto construct the bays prior to cable pulling to prevent any damage tothe cable at a later stage.

(e)In the unlikely event of a cable failure in the future, quoting the cabledrum serial number will assist the cable manufacturer in his qualitycontrol, as this serial number is related to the manufacturing and rawmaterial management in the factory.

(f)

The following“VITALACTIONS”must be observed prior to a cable pull.

(i) Cable rollers must be placed between 2 and 3 m apart in thetrench(depending on size of cable) (See fig. 4a on page 23).

(ii) Ensure that graphite lubricants have been applied wherenecessary.

(iii) Check that skid plates are secure and in position, corner rollersare a good alternative (See fig. 4b on page 23).

(iv) Ensure that each member of the pulling gang knows exactlywhat he is to do and that communication signals betweenmembers are clear.

(v) The trench floor must be clear of stones and otherobstructions and the cable bedding correctly dispersed.

Positioning of Joint Bays

Recording Cable Drum Serial Numbers on“As Laid”Drawings

Preparing for Cable Laying

23

Ensure that:

(vi) Cable covers are available at convenient points.

(vii) Any objects that may fall into the trench and damage the cableduring the pull and prior to backfilling have been removed.

(viii) If the ambient temperature is below 10°C or has been so forthe past 24 hours, the cable on the drum will have to becovered with a tarpaulin and heated with suitable lamps orheaters for at least 24 hours under close supervision. Ensurethat sufficient ventilation exists, and pay the cable off the drumslowly and carefully. The drum should be lagged with only afew of the bottom lags removed during the heating process.

(ix) Place the drum at a convenient point prior to the pull on strongjacks and on sound footing (as mentioned earlier) with thearrow on the drum flanges POINTING IN THE OPPOSITEDIRECTION to the rotation when the cable is being pulled.

(x) Before pulling, cut the inner end of the cable free.

(xi) Remove the drum battens carefully and from the bottom.

(xii) Inspect the cable ends for any sign of leakage (especially Paperinsulated cables). If a leak is suspected, it can be proved byheating the cap until just too hot to touch and insulating oil willexude out, the cap should then be removed and the extent ofthe damage assessed, by means of the dielectric test (SeeSection 4.2). Cables with extruded dielectrics should besealed and free from moisture.

(xiii) The cable must be payed off from the top of the drum but takecare not to bend it too sharply.

(a) Cable Roller

(c) Cable Stocking

(b) Corner Roller

(d) Pulling Eye

Figure 4

24

(xiv) Cable pulling stockings should be examined and placed overthe nose of the cable with care (see fig. 4c & d on pg 23). Thepulling rope or wire must be attached to the stocking in such away that the cable cap will not be damaged during the pull.Theuse of swivels is recommended to prevent twisting of thestocking. The use of stockings is preferable to tying a ropedirectly to the cable for pulling-in.

(xv) For permissible mechanical forces see Section 3.4.

(xvi) Bending radius of cables as recommended by the manufac-turer should not be exceeded. They are:

CableTypeBending

Radius up to& including

11kV

22 kV&

33 kV

• Single Core

• Multicore

• Multi and Single Core 16-50 sq mm

• Armoured Multi & Single Core 70 sq mm and greater

• Single Core

• Multicore

Paper Insulated Cables

PVC Insulated Cables 1000 Volt

XLPE Insulated Cables

Table 3.2 : Recommended Bending radii

20 x d

12 x d

8 x d

10 x d

17 x d

15 x d

25 x d

15 x d

-

-

17 x d

15 x d

Where is the diameter over the outer sheath.d

(xvii) One man should remain at the drum and “brake” the drum inorder to maintain the correct tension on the cable during thepull.

(xviii) Cables should be pulled to their final position in a continuousmanner.

(xix) If a winch is being used to pull the cable and unavoidable sharpbends are encountered, a snatch block could be used to assistthe pulling tension at bend (See fig. 5).

Skid plates

Cable pulled to a position as nearsnatch block as possible. Thencable and bond detached fromblock and positioned around skidplatesas shown.

Figure 5

25

(xx) Heavy lead-sheathed Paper insulated cables in long lengthsmay need very large gangs of men if no winch is used; lighterXLPE insulated cables require fewer men.

(g)Once the cable pull is completed, the nose-end of the cable iscarefully lifted off the rollers and placed on the bottom of the trench,leaving enough slack to terminate the cable and observing theminimum bending radius. Immediately after cutting, the cable shouldbe suitably sealed on both ends of the cut to prevent the ingress ofmoisture. Examine the nose cap and make good any damage thatmay have occurred during pulling.

(h)These techniques are applied when heavy cables are to be laid or thetrench undergoes many changes of direction or very long lengths ofcable have to be laid, or a combination of these.

As in the previously mentioned methods of cable pulling, the trenchwould have been prepared with cable rollers, corner rollers and skidplates. Snatch blocks would have been anchored to the sides of thetrench at bends and a winch placed at the far end of the section. Atthe near end a mobile bond carrier is placed conveniently adjacent tothe cable drum, ensuring that its braking system is adequate and thatit has rewinding facilities. A steel rope, more than twice the length ofthe cable to be pulled, is wound onto the bond carrier drum and its endfed over the rollers and through the snatch blocks and then secured tothe drum of the winch.

The cable end is manhandled onto the first rollers and tied to the steelrope (See fig. 6) at intervals of about 2 metres. Start the winch and asthe nose of the cable arrives at the snatch block untie it from the steelcable, take it around the corner roller and retie on the straight.

Once the nose has reached the winch end, and allowing thenecessary slack, the cable can be untied, the steel rope rewound ontothe bond carrier. Further preparation for backfilling may then becommenced.

Sealing of Cable Ends

Bond Pulling

Figure 6 : Bond Pulling

Ties Applied at not Greaterthan 2 Metre Intervals

Steel wire bond

Mobile Bond Carrier

Cable drum Cable tied

Cable re-tied

Cable re-tied

Cable untied

Cable untied

Snatch block

Skid plate

Joint bay

joint bay

Winch

Cable

Cable

Bond wire

Cable tied to bond

26

3.7 Backfilling and Reinstatement

3.8 Repairs to PVC oversheaths

Superficial Damage

Holes or Slits in the PVC Sheath

Removal of a complete section of oversheath

Once the cables have been laid, and before commencing with backfillingcarry out a visual inspection of the installation to ensure that:

(a) The cables are properly bedded.(b) Correct spacing between cables if there is more than one in the

trench.(c) Cable entrances at ducts are suitably protected against the possibility

of vermin gaining entrance.(d) Laying and pulling equipment has been removed.(e) That there is no obvious damage to cable sheaths. Up to 90% of the

service failures experienced in any cable system can be avoided ifappropriate action is taken at this stage.

As mentioned above PVC sheaths damaged ‘during pulling’ should berepaired taking every care to do a workmanlike job.

(a)Generally the local area damaged should be removed, the remainingsheath chamfered for 25 mm at the edges. A EPR self-amalgamatingtape is then applied after cleaning the affected area thoroughly witha suitable solvent (i.e. Genklene). The PVC tape should be approxi-mately 30 mm wide and is applied under tension with a 50% overlapcontinuing up the chamfer until the top is reached plus 4 layersextending 75 mm beyond the chamfer.

(b)Chamfer the edges of the damaged area for a distance of 30 mm andabrade the area with Carborundum strip for a further 20mm.

Clean the area with a solvent and apply a filling putty (B sealing tape)followed by a layer of EPR self-amalgamating tape applied at hightension extending 50 mm from the patch, followed by 3 layers of PVCtape extending 100 mm from the edges of the EPR tape.

(c )Upon removal of the damaged ring, chamfer the remaining edges fora distance of 30 mm, clean with the solvent and apply 4 layers of EPRtape at high tension to 50 mm beyond the chamfer. Apply PVC self-adhesive tape at one third overlap to a level corresponding to theoriginal over sheath diameter. Five layers of PVC self-adhesive tapeare then applied, each one extending 5 mm further along the cable.

The repair is then completed with a resin poultice reinforcementconsisting of 6 layers of ribbon gauge or bandage, impregnated andpainted with an approved grade of freshly mixed epoxy resin. Allow12 hours to cure.

27

4.0 Paper InsulatedAnd Lead-covered 6.35/11kV Cables

4.1 Notes on impregnating compound

4.2 Moisture in Paper cables

MoistureTest

The following chapter generally covers 6.35/11kV PILC cables. For highervoltages or single core applications please consult our application engi-neers for specialised technical or installation information. The cablesdescribed in this section are manufactured according to SANS 97. (Forgreater details see brochure covering this product).

Present day paper insulated cable are mass impregnated with non-drainingcompound (MIND). This Poly-Iso-Butylene compound remains in a solidstate at normal operating temperatures and melts at a p p r o x i m a t e l y100°C.

Compound migration, as was experienced in earlier rosin-oil impregnatedcables installed vertically or on inclines, has thus been eliminated by theuse of this non-draining compound.

If cable is damaged and the lead sheath or end cap is punctured, moisturealmost invariably penetrates into the insulation and, if not detected imm-ediately and removed, may cause trouble at a later date. In every suchcase, therefore, a moisture test should be carried out and the cable cutback until all traces of dampness are removed. The following simple, butreliable test is recommended:

Heat about 1 litre of oil compound (or melted paraffin wax)in a saucepan toa temperature of 150°C (check by thermometer). Remove individual papertapes from the cable under test and immerse them in the hot compound.If any moisture is present, it will boil out of the paper and form bubbles orfroth, which will rise to the surface of the liquid. If no moisture is present,the hot compound will be undisturbed.

When carrying out the above test do not handle the portion of the papertapes to be immersed in the compound, as moisture from the hands maygive rise to false conclusions. As moisture is most likely to travel along thecable under the lead sheath or along the conductors, the papers next to thesheath and conductors are those most likely to contain moisture.

To minimise the penetration of moisture into the cable from the atmos-phere or other sources, the cores should be moisture-blocked at each end,by sweating them solid or using solid centre ferrules.

Table 4.1 : Current Rating Parameters

Maximum sustained conductor temperatureGround TemperatureAmbient air temperature (free air-shaded)Ground Thermal ResistivityDepth of laying to top of cable or duct

70°C

25°C

30°C

1,2K.m/W

800mm

28

25 35 50 70 95 120

150

185

240

300

31,3

8

33,6

4

33,4

9

36,5

0

39,3

3

41,7

3

44,3

6

47,4

2

52,1

4

56,1

5

105

130

160

195

235

265

295

335

380

425

4890

5710

6020

7080

8260

9440

1077

0

1229

0

1448

0

1694

0

80 100

125

155

185

210

235

265

305

340

1,44

21

1,04

92

0,77

77

0,54

23

0,39

72

0,31

83

0,26

40

0,21

66

0,17

34

0,14

72

1,90

0

2,66

0

3,80

0

5,32

0

7,22

0

9,12

0

11,4

00

14,0

60

18,2

40

22,8

00

31,3

8

33,6

4

33,4

9

36,5

0

39,3

3

41,7

3

44,3

6

47,4

2

52,1

4

56,1

5

4415

5055

5195

5790

6505

7225

7980

8870

1005

0

1141

5

0,87

79

0,63

71

0,47

51

0,33

65

0,24

99

0,20

53

0,17

39

0,14

81

0,12

45

0,11

06

2,87

5

4,02

5

5,75

0

8,05

0

10,9

25

13,8

00

17,2

50

21,2

75

27,6

00

34,5

00

Tab

le 4

.2E

lect

rical

and

Phy

sica

l Pro

pert

ies

of 3

cor

e Pa

per

insu

late

d an

d le

ad c

over

ed d

oubl

e st

eel t

ape

arm

oure

d Ju

te S

erve

d 6.

35/1

1kV

cab

les

to S

AN

S 9

7Ta

ble

17 (G

ener

al p

urpo

se b

elte

d)

(mm

)(m

m)

(kg

/km

)(A

)(A

)(

/km

)W

(/k

m)

W(k

g/k

m)

(mm

²)(k

A)

(kA

)

Ele

ctr

ical P

rop

ert

ies

Ele

ctr

ical P

rop

ert

ies

Ph

ysic

al P

rop

ert

ies

Ph

ysic

al P

rop

ert

ies

Cab

le

Siz

e

CO

PP

ER

CO

ND

UC

TO

RS

ST

RA

ND

ED

ALU

MIN

IUM

CO

ND

UC

TO

RS A

pp

rox.

Cab

leM

ass

Dia

mete

ro

ver

lead

1 s

eco

nd

sh

ort

cir

cu

itra

tin

g

Imp

e-

dan

ce

Cu

rren

tra

tin

g(G

rou

nd

)

Ap

pro

x.

Cab

leM

ass

Dia

mete

ro

ver

lead

1 s

eco

nd

sh

ort

cir

cu

itra

tin

g

Imp

e-

dan

ce

Cu

rren

tra

tin

g(G

rou

nd

)

(Sho

rt c

ircui

t ra

tings

bas

ed o

n te

mpe

rat u

re r

ise

of 7

0°C

to

1 60°

C)

29

4.3 Derating factors for non-standard conditions

Table 4.3.4 : Ground Temperature derating factors

MaximumConductor

Temperature (70°C)

GroungTemperatures (°C)

25

1,00

30

0,95

35

0,90

40

0,85

45

0,80

Table 4.3.3 : Grouping of PILC cables in Horizontal Formation at standard soilconditions (multicore cables)

No ofCables

inGroup

Direct in Ground In Single Way Ducts

Axial Spacing (mm) Axial Spacing (mm)

Touching 150 300 300450 450600 600Touching

2

3

4

5

6

0,80

0,69

0,63

0,57

0,55

0,88

0,80

0,75

0,71

0,69

0,85

0,75

0,70

0,66

0,63

0,91

0,84

0,81

0,77

0,75

0,89

0,80

0,77

0,73

0,71

0,90

0,84

0,80

0,78

0,76

0,92

0,86

0,84

0,81

0,80

0,94

0,89

0,87

0,85

0,84

0,93

0,87

0,84

0,82

0,80

Ground Thermal Resistivity (Multicore PILC cables)Table 4.3.2 :

1,0

1,2

1,5

2,0

2,5

1,07

1,00

0,92

0,84

0,75

1,03

1,00

0,95

0,88

0,82

Thermal Resistivity(K.m/W)

Direct in Ground In Single Way Ducts

Depth of Laying (mm) Direct in Ground In Single Way Ducts

800

1000

1250

1500

2000

1,00

0,98

0,96

0,95

0,92

1,00

0,99

0,97

0,96

0,94

Table 4.3.1 : Depth of laying - multicore PILC cables (up to 300 mm²)

30

4.4 Short circuit ratings for PILC cables

Short circuit ratings do not lend themselves to rigid treatment due tounknown variables, and wherever possible conservative values should beapplied.

With the continued growth of power system fault capacity, attention mustbe given, when selecting a cable, to its short circuit capacity as well as tothe continuous current rating.

Other limiting effects in avoiding damage during subsequent short circuitconditions are as follows:-

(a) Weakening of joints due to softening of solder at conductor tempera-tures above 160°C.

MaximumConductor

Temperature (70°C)

AirTemperatures (°C)

25

1,10

30

1,00

35

0,94

40

0,87

45

0,79

Table 4.3.5 : Air Temperature derating factors

Solar Radiation

Correction FactorsCross-SectionalArea of Conductor

1250 W/m² (Highveld)1000 W/m² (Coastal)mm²

0,62

0,57

0,53

0,49

0,44

1,5 - 10

16 - 35

50 - 95

120 - 185

240 - 400

0,70

0,68

0,65

0,62

0,59

Table 4.3.6 : Correction factors for direct solar radiation

Note:

Horizontal formation

Vertical formation

Note:

PILC Cables may be grouped in air without derating providing thatthe cables are installed on cable ladders, and that for:

(a)The clearance between cables is not less than 2 x the overalldiameter of the largest cable (or 150 mm) whichever is least.

(b)(i) The clearance from a supporting wall is greater than 20 mm,

and(ii) The vertical clearance between cables is greater than 150 mm.

If the number of cables > 4, they are to be installed in a horizontal plane.

31

(b) If crimped or welded ferrules and lugs are used (see A - 1.2 ofannex A SANS 97) temperatures of 250°C can be tolerated.

(c) Bursting effects are only of concern with unarmoured screenedcables larger than 150 mm². Multicore wire armoured cables are onlylikely to burst at currents in excess of 33 kA for cable sizes below70mm², in excess of 39 kA for cables below 150 mm² and in excessof 22 kA for cables below 300 mm².

Cable short circuit ratings are based on the adiabatic performance of theconductors and may thus be regarded as “internal ratings” which are notaffected by external factors as in the case of current ratings. Therefore, noderating factors are needed.

Ratings are derived from temperature limits as follows:-

The values of K for copper and aluminium conductors of 6.35/11 kV PILCcables are 115 & 76 amps/mm² respectively, for a conductor temperaturerising from 70°C to 160°C.

on pg 28 provides 1 second short circuit ratings.

Some systems make provision for reducing earth fault currents by theinclusion of a neutral earthing resistor (NER) at the star point of thedistribution transformer.

Where this is not the case, the resultant high earth fault current under afault condition will be carried by the lead sheath and by the galvanised steelwire armour. The bitumised steel tape armour is expected to rust in timeand should not be included in any calculation to carry fault current.

The value of K for lead sheaths and galvanised steel wire armour is 24 & 44amps/mm² respectively. The following formula must be applied:

The area of the lead sheath and the armour wires of the cable must beobtained.

Reference to SANS 97 will provide the necessary information.

where I = short circuit rating in AmpsK = constant combining temperature limits and conductor

material propertiesA = area of conductort = duration of short circuit in seconds

Table 4.2

4.5 Earth Fault Ratings

I =

K x AAmps

t

I =

K x AAmps

t

32

5.0 Medium Voltage XLPE Insulated, PVC Bedded, SWA, PVC sheathedcables

QualityAssurance

5.1 Notes on XLPE Insulation

The following chapter generally covers 6.35/11kV XLPE cables. For highervoltages or single core applications please consult our applicationengineers for specialised technical or installation information. The cablesdescribed in this section are manufactured according to SANS 1339. (Forgreater details see brochure covering this product).

MV XLPE cable manufactured by Aberdare Cables is required to undergo apartial discharge test at our Standford Road Port Elizabeth factory. Thepartial discharge measurement technique involves scanning of everymetre of every drum of cable using the only such scanner installed in theSouthern Hemisphere. The technique has been in use since the intro-duction of XLPE by Aberdare Cables and has given superb performanceover the past 20 years.

The advantage of the scanning technique is that non-complying XLPEcores can be re-insulated before they are further processed (application ofcopper tape screen, laying up of 3 cores, application of PVC bedding,application of Steel Wire Armour and extrusion of outer sheath). Althoughthis is a expensive operation, it is dramatically cheaper than rectification offaults at final test or after installation on the customer premises. Infactories where partial discharge detection is carried out only as a finaltest, and assuming a non-complying partial discharge is detected, thedecision to scrap the cable or alternatively to strip and replace an XLPEcore will be very costly.

The advantage to the customer of the above testing is that he is assured ofquality cable with an acceptable level of partial discharge.

Aberdare’s unrivalled quality record in experiencing only one field failure ofXLPE cable during its twenty years of manufacture of this product isadequate proof of the superiority of this testing method.

For XLPE insulated conductors, continuous conductor temperatures of90°C are permissible with overload excursions up to 130°C for a maximumof 8 hours continuous per event, with a maximum total of 125 hours perannum. In the case of short circuits the insulation can withstand conductortemperatures of up to 250°C for 1 second.

Maximum sustained conductor temperatureGround TemperatureAmbient air temperature (free air-shaded)Ground Thermal ResistivityDepth of laying to top of cable or duct

90°C

25°C

30°C

1,2K.m/W

800mm

Table 5.1 : Current ratings are based on these parameters

33

Tab

le 5

.2E

lect

rical

and

Phy

sica

l Pro

pert

ies

of 3

cor

e X

LPE

insu

late

d P

VC b

edde

d, s

teel

wire

arm

oure

d, P

VC s

heat

hed

6.35

/11k

V c

able

s to

SA

NS

133

9Ty

peA

(Indi

vidu

ally

scr

eene

d)

(mm

)(m

m)

(kg

/km

)(A

)(A

)(

/km

)W

(/k

m)

W(k

g/k

m)

(mm

²)(k

A)

(kA

)

Ele

ctr

ical P

rop

ert

ies

Ele

ctr

ical P

rop

ert

ies

Ph

ysic

al P

rop

ert

ies

Ph

ysic

al P

rop

ert

ies

Cab

le

Siz

e

CO

PP

ER

CO

ND

UC

TO

RS

ST

RA

ND

ED

ALU

MIN

IUM

CO

ND

UC

TO

RS A

pp

rox.

Cab

leM

ass

Dia

mete

ro

ver

lead

1 s

eco

nd

sh

ort

cir

cu

itra

tin

g

Imp

e-

dan

ce

Cu

rren

tra

tin

g(G

rou

nd

)

Ap

pro

x.

Cab

leM

ass

Dia

mete

ro

ver

lead

1 s

eco

nd

sh

ort

cir

cu

itra

tin

g

Imp

e-

dan

ce

Cu

rren

tra

tin

g(G

rou

nd

)

25 35 50 70 95 120

150

185

240

300

47,3

49,7

52,6

56,3

60,5

64,2

68,8

72,8

79,1

85,6

140

170

200

240

290

325

360

410

470

520

4655

5215

5895

6995

8170

9370

1124

0

1277

5

1495

5

1786

5

0,93

53

0,67

83

0,50

67

0,35

81

0,26

65

0,21

87

0,18

47

0,15

71

0,13

17

0,11

60

155

190

225

255

285

320

370

420

3,57

5

5,00

5

7,15

0

10,0

10

13,5

85

17,1

60

21,4

50

26,4

55

34,3

20

42,9

00

0,82

84

0,57

67

0,42

13

0,33

75

0,27

95

0,22

85

0,18

21

0,15

35

4,60

0

6,44

0

8,74

0

11,0

40

13,8

00

17,0

20

22,0

80

27,6

00

52,6

56,3

60,5

64,2

68,8

72,8

79,1

85,6

5015

5635

6340

7045

8350

9245

1058

0

1207

0

34

Table 5.2.4 : Ground Temperature derating factors

25

1,0

30

0,96

35

0,92

40

0,88

45

0,84

MaximumConductor

Temperature (90°C)

Ground Temperatures (°C)

5.2 Derating factors for non-standard conditions

Table 5.2.3 : Group of XLPE cables in horizontal formation at standard depthsof laying and in standard soil conditions (multicore cables)

No ofCables

in Group

Direct in Ground In Single Way Ducts

Axial Spacing (mm) Axial Spacing (mm)

Touching 250 700 Touching 250 700

0,79

0,69

0,63

0,58

0,55

0,87

0,80

0,75

0,72

0,69

0,85

0,75

0,68

0,64

0,60

0,91

0,86

0,80

0,78

0,74

0,87

0,79

0,75

0,72

0,69

0,93

0,91

0,87

0,86

0,83

2

3

4

5

6

Ground thermal resistivity - multicore XLPE cables(up to 300 mm²)

Table 5.2.2 :

Thermal Resistivity(K.m/W)

Direct in Ground In Single Way Ducts

0,7

1,0

1,2

1,5

2,0

2,5

3,0

1,23

1,08

1,00

0,90

0,80

0,72

0,66

1,28

1,12

1,00

0,93

0,85

0,80

0,74

Depth of Laying (mm) Direct in Ground In Single Way Ducts

Table 5.2.1 : Depth of laying - multicore XLPE cables (up to 300 mm²)

500 - 800

850 - 1000

1050 - 1200

1250 - 1400

1450 - 1600

1,00

0,97

0,95

0,93

0,92

1,00

0,96

0,95

0,95

0,94

35

Note:

Horizontal formation

Vertical formation

Note:

Cables may be grouped in air without derating provided that the cablesinstalled on cable ladders, and that for:

(a)The clearance between cables is not less than 2 x the overalldiameter of the largest cable (or 150 mm) whichever is least.

(b)The clearance from a supporting wall is greater than 20 mm, andThe vertical clearance between cables is greater than 150 mm.

If the number of cables > 4, they are to be installed in a horizontalplane.

5.3 Short circuit ratings for XLPE insulated 6.35/11 kV cables

Short circuit ratings do not lend themselves readily to rigid treatment dueto unknown variables. Wherever possible conservative values should beapplied. As the growth of a power system increases so do the systemfault levels. When selecting a cable attention must be given to it’s shortcircuit capability, as well as to the continuous current ratings.

Other limiting effects in avoiding damage during short circuit conditions areas follows:-

(a) Weakening of joints due to softening of the solder at a conducttemperature of 160°C and above, although most conductor joiningnowadays is done by compression fittings, particularly on XLPEinsulated cables.

Solar Radiation

Correction FactorsCross-SectionalArea of Conductor

1250 /m² (Highveld)W1000 /m² (Coastal)Wmm²

0,62

0,57

0,53

0,49

0,44

1,5 - 10

16 - 35

50 - 95

120 - 185

240 - 400

0,70

0,68

0,65

0,62

0,59

Table 5.2.6 : Correction factors for direct solar radiation

MaximumConductor

Temperature (90°C)30

1,0

35

0,95

40

0,89

45

0,84

50

0,78

Table 5.2.5 : Air Temperature derating factors

AirTemperatures (°C)

(b) Bucking of the conductors in joint boxes due to longitudinal expansionof cables laid direct in ground.

Cables short circuit ratings are based on the adiabatic performance of theconductors. This assumes no heat loss from the cable during the period ofthe fault. No derating factors are necessary with regard to soiltemperature, depth of burial etc.

Ratings are derived from temperature limits as follows:-

Where I = Short circuit rating in AmpsK = constant combining temperature limits and conductor

material propertiesA = area of Conductort = duration of short circuit in seconds

The value of K for copper and aluminium conductors of 6.35/11 kV XLPEcables is 143 & 92 amps/mm² respectively, for a conductor temperaturerising from 90°C to 250°C.

Some systems provide for reducing earth fault currents by the inclusion ofa neutral earthing resistor (NER) at the star point of the distributiontransformer, to typically 300 A.

Where this is not the case, the resistance of the copper tapes and steelwire armour should be included in the calculation.

Typical 1 second Earth Fault ratings for XLPE insulated 6.35/11 kVType A cables manufactured to SANS 1339 - 1991 are shown in table 5.3

5.4 Earth Fault Current

36

Cable Size Earth Fault Rating

Table 5.3 : Earth fault ratings

mm² kA/s

25

35

50

70

95

120

150

185

240

300

10,4

12,2

13,1

17,6

18,7

19,7

20,8

25,0

26,8

28,6

I =

K x AAmps

t

37

6.2 Physical dimensions of the cables are given in terms of the sketchbelow and these abbreviations are used in the tables.

C/S OF SINGLE CORE CABLE

D1 = diameter over bedding

d = diameter of armour wires

D2 = diameter over outer sheath

6.0 Low Voltage PVC and XLPE Insulated 600/1000V Power Cables toSANS 1507

6.1 Note on PVC insulation

Note of XLPE insulation

For PVC insulation continuous conductor temperatures up to 70°C arepermissible. Care must be exercised in matching the cable to the circuitprotection. Under short circuit conditions, a maximum conductortemperature of 160°C is allowed for a maximum period of 1 second.

For XLPE insulation, continuous conductor temperature up to 90°C arepermissible with excursions of up to 130°C or a maximum of 8 hourscontinuous per event, with a maximum total of 125 hours per annum.

D1

d

D2

Table 6.1 : Current rating parameters

Maximum sustained conductor temperature

Ground temperature

Ambient air temperature (free air shaded)

Ground Thermal Resistivity

Depth of laying to top of cable or duct

PVC XLPE

70°C

25°C

30°C

1,2 K.m/W

500mm

90°C

25°C

30°C

1,2 K.m/W

500mm

38

Tab

le 6

.2E

lect

rical

and

Phy

sica

l Pro

pert

ies

of 3

and

4 c

ore

PVC

Insu

late

d P

VC b

edde

d S

WA

PVC

she

athe

d 60

0/10

00V

cab

les

man

ufac

ture

d to

SA

NS

150

7-3

CO

PP

ER

CO

ND

UC

TO

RS

Cu

rren

t R

ati

ng

No

min

al

Dia

me

ters

Ph

ysic

al

Pro

pe

rtie

sE

lectr

ical P

rop

ert

ies

Ap

pro

x.M

ass

3 Vo

ltd

rop

f

(mV

/A/m

)

1 Vo

ltd

rop

f

(mV

/A/m

)(m

m)

D1

dD

2

(mm

)(m

m)

(mm

)(m

m)

(mm

)(k

g/k

m)

Gro

un

d

(A)

Du

cts

(A)

Air

(A)

Imp

e-

dan

ce

(/k

m)

W(k

g/k

m)

1,5

2,5 4 6 10 16 25 35 50 70 95 120

150

185

240

300

24 32 42 53 70 91 119

143

169

210

251

285

320

361

416

465

20 26 34 43 58 75 96 116

138

171

205

234

263

298

344

385

14,4

8

8,87

5,52

3,69

2,19

1,38

0,87

49

0,63

35

0,47

18

0,33

25

0,24

60

0,20

12

0,16

98

0,14

45

0,12

20

0,10

90

25,0

80

15,3

63

9,56

1

6,39

1

3,79

3

2,39

0

1,51

5

1,09

7

0,81

7

0,57

6

0,42

7

0,34

8

0,29

4

0,25

0

0,21

1

0,18

9

28,9

56

17,7

34

11,0

34

7,37

4

4,38

4

2,75

9

1,74

9

1,26

7

0,94

4

0,66

5

0,49

2

0,40

2

0,33

9

0,28

9

0,24

4

0,21

8

8,51

9,61

11,4

0

12,5

8

14,5

9

16,5

5

19,4

6

20,8

9

24,2

6

27,0

7

31,1

9

33,3

8

36,6

8

40,8

2

46,4

3

51,1

0

9,33

10,5

6

12,5

7

13,9

0

16,1

4

19,1

8

21,3

4

23,9

7

28,1

4

31,2

9

35,8

2

38,1

0

42,0

5

46,7

5

53,0

6

58,5

3

1,25

1,25

1,25

1,25

1,25

1,25

1,60

1,60

1,60

2,0

0

2,0

0

2,0

0

2,0

0

2,50

2,50

2,50

1,25

1,25

1,25

1,25

1,25

1,60

1,60

1,60

2,0

0

2,0

0

2,0

0

2,0

0

2,50

2,50

2,50

2,50

14,1

3

15,2

3

17,0

2

18,4

0

20,4

1

22,3

7

26,4

6

27,8

9

31,4

6

35,4

7

39,9

9

42,1

8

45,9

8

51,1

2

57,1

3

62,2

0

14,9

5

16,1

8

18,3

9

19,7

2

21,9

6

25,9

2

28,3

4

31,1

7

36,5

4

40,0

9

44,6

2

47,4

0

52,6

5

57,4

5

64,1

6

70,1

3

448

522

667

790

996

1295

1838

2215

2871

3617

4901

5720

6908

8690

1076

7

1295

0

19 26 35 45 62 83 110

135

163

207

251

290

332

378

445

510

501

597

762

910

1169

1768

2196

2732

3893

4837

6115

7269

9250

1103

9

1372

6

1654

4

Cab

le

Siz

e

(mm

²)

3c

3c

3c

3c

4c

4c

4c

4c

39

Tab

le 6

.3E

lect

rical

and

Phy

sica

l Pro

pert

ies

of 3

and

4 c

ore

PVC

Insu

late

d P

VC b

edde

d S

WA

PVC

she

athe

d 60

0/10

00V

cab

les

man

ufac

ture

d to

SA

NS

150

7-3

ALU

MIN

IUM

CO

ND

UC

TO

RS

Cu

rren

t R

ati

ng

No

min

al

Dia

me

ters

Ph

ysic

al

Pro

pe

rtie

sE

lectr

ical P

rop

ert

ies

Ap

pro

x.M

ass

3 Vo

ltd

rop

f

(mV

/A/m

)

1 Vo

ltd

rop

f

(mV

/A/m

)(m

m)

D1

dD

2

(mm

)(m

m)

(mm

)(m

m)

(mm

)(k

g/k

m)

Gro

un

d

(A)

Du

cts

(A)

Air

(A)

Imp

e-

dan

ce

(/k

m)

W(k

g/k

m)

Cab

le

Siz

e

(mm

²)

3c

3c

3c

3c

4c

4c

4c

4c

25 35 50 70 95 120

150

185

240

90 108

129

158

192

219

245

278

324

73 87 104

130

157

179

201

229

268

80 99 119

151

186

216

250

287

342

1,44

46

1,04

65

0,77

49

0,53

88

0,39

34

0,31

48

0,26

07

0,21

33

0,17

08

2,50

2

1,81

3

1,34

2

0,93

3

0,68

1

0,54

5

0,45

2

0,36

9

0,29

6

2,88

9

2,09

3

1,54

9

1,07

8

0,78

7

0,62

9

0,52

1

0,42

7

0,34

2

17,7

6

19,3

3

21,8

7

24,7

6

28,6

8

31,0

9

33,9

9

37,8

0

42,6

0

20,6

5

21,9

3

25,0

5

29,2

7

33,7

3

35,4

4

39,3

9

44,5

1

50,0

4

1,60

1,60

1,60

1,60

2,0

0

2,0

0

2,0

0

2,0

0

2,50

1,60

1,60

1,60

1,60

2,0

0

2,0

0

2,50

2,50

2,50

24,7

6

26,3

3

29,0

7

31,9

6

37,0

8

39,8

9

42,7

9

47,1

0

52,9

27,6

5

29,1

3

32,2

5

37,6

7

42,5

3

44,2

4

49,6

9

54,8

1

61,1

4

1301

1477

1782

2132

2908

3328

3837

4557

5977

1554

1757

2150

2930

3647

4023

5276

6231

7550

70°C

70°C

70°C

90°C

90°C

90°C

26 34 45 55 75 94 123

148

177

216

258

293

329

371

428

482

30 40 52 64 87 110

143

172

206

252

302

344

387

435

498

558

21 28 36 44 60 76 98 119

142

175

209

238

268

302

349

401

25 32 42 52 70 89 116

139

167

205

248

282

318

359

413

471

16 21 28 35 48 60 107

132

163

206

251

291

334

383

453

520

22 30 39 49 68 85 132

163

200

253

312

362

416

478

557

634

Tab

le 6

.4E

lect

rical

and

Phy

sica

l Pro

pert

ies

of 3

and

4 c

ore

XLP

E In

sula

ted

PVC

bed

ded

SW

A P

VC s

heat

hed

600/

1000

V c

able

s m

anuf

actu

red

to S

AN

S 1

507-

4

CO

PP

ER

CO

ND

UC

TO

RS

Cu

rren

t R

ati

ng

No

min

al

Dia

me

ters

Ph

ysic

al

Pro

pe

rtie

sE

lectr

ical P

rop

ert

ies

Ap

pro

x.M

ass

3 Vo

ltd

rop

f

(mV

/A/m

)

1 Vo

ltd

rop

f

(mV

/A/m

)(m

m)

D1

dD

2

(mm

)(m

m)

(mm

)(m

m)

(mm

)(k

g/k

m)

Gro

un

dD

ucts

Air

Imp

e-

dan

ce

(/k

m)

W(k

g/k

m)

Cab

le

Siz

e

(mm

²)

3c

3c

3c

3c

4c

4c

4c

4c

1,5

2,5 4 6 10 16 25 35 50 70 95 120

150

185

240

300

15,4

3

9,45

5,88

3,93

2,33

1,46

0,93

13

0,67

38

0,50

09

0,35

21

0,25

89

0,21

09

0,17

75

0,15

00

0,12

47

0,10

99

26,7

26

16,3

68

10,1

84

6,80

7

4,05

3

2,54

6

1,61

3

1,16

7

0,86

8

0,61

0

0,44

8

0,36

5

0,30

7

0,26

0

0,21

6

0,19

0

30,8

61

18,9

00

11,7

61

7,86

2

4,66

3

2,92

4

1,86

3

1,34

8

1,00

2

0,70

4

0,51

8

0,42

2

0,35

5

0,30

0

0,24

9

0,21

9

8,08

9,18

10,0

6

11,2

5

13,2

5

15,2

1

18,1

3

19,5

6

22,4

9

25,7

4

28,7

6

31,3

9

34,6

9

39,0

5

44,2

2

48,4

5

8,85

10,0

8

11,0

7

12,4

0

14,6

4

17,6

8

19,8

6

22,3

2

25,7

6

29,8

1

33,1

35,8

7

40,1

2

44,7

7

50,5

8

55,5

6

1,25

1,25

1,25

1,25

1,25

1,25

1,60

1,60

1,60

2,00

2,00

2,00

2,50

2,50

2,50

2,50

1,25

1,25

1,25

1,25

1,25

1,25

1,60

1,60

1,60

2,00

2,00

2,00

2,50

2,50

2,50

2,50

13,7

0

14,8

0

15,6

8

16,8

7

19,0

7

21,0

3

25,1

3

26,5

6

29,6

9

32,9

4

37,1

6

40,1

9

43,4

9

49,3

5

54,5

2

58,3

5

14,4

7

15,7

0

16,6

9

18,0

2

20,4

6

24,4

2

26,8

6

29,5

2

32,9

6

38,2

1

41,9

0

44,6

7

50,4

2

55,0

7

61,6

8

67,1

6

416

487

566

683

890

1191

1693

2025

2606

3323

4442

5335

6403

8184

1007

3

1207

6

453

521

650

778

1033

1544

2018

2511

3242

4503

5650

6731

8708

1034

3

1293

2

1557

5

40

41

Tab

le 6

.5E

lect

rical

and

Phy

sica

l Pro

pert

ies

of 3

and

4 c

ore

XLP

E In

sula

ted

PVC

bed

ded

SW

A P

VC s

heat

hed

600/

1000

V c

able

s m

anuf

actu

red

to S

AN

S 1

507-

4

ALU

MIN

IUM

CO

ND

UC

TO

RS

Cu

rren

t R

ati

ng

No

min

al

Dia

me

ters

Ph

ysic

al

Pro

pe

rtie

sE

lectr

ical P

rop

ert

ies

Ap

pro

x.M

ass

3 Vo

ltd

rop

f

(mV

/A/m

)

1 Vo

ltd

rop

f

(mV

/A/m

)(m

m)

D1

dD

2

(mm

)(m

m)

(mm

)(m

m)

(mm

)(k

g/k

m)

Gro

un

d

(A)

Du

cts

(A)

Air

(A)

Imp

e-

dan

ce

(/k

m)

W(k

g/k

m)

Cab

le

Siz

e

(mm

²)

3c

3c

3c

3c

4c

4c

4c

4c

108

131

160

200

245

285

328

378

438

1,54

08

1,11

59

0,82

58

0,57

36

0,41

78

0,33

37

0,27

56

0,22

47

0,17

85

2,66

9

1,93

3

1,43

0

0,99

4

0,72

4

0,57

8

0,47

7

0,38

9

0,30

9

3,08

2

2,23

2

1,65

2

1,14

7

0,83

6

0,66

7

0,55

1

0,44

9

0,35

7

15,5

3

18,0

0

20,0

9

23,4

3

25,8

5

29,0

9

32,1

5

36,0

2

40,3

9

19,1

6

20,4

4

23,0

6

27,3

8

30,9

9

33,2

0

36,7

5

42,5

2

50,4

0

1,25

1,60

1,60

1,60

1,60

2,0

0

2,0

0

2,0

0

2,50

1,60

1,60

1,60

1,60

2,0

0

2,0

0

2,0

0

2,50

2,50

21,5

3

25,0

0

27,0

9

30,6

3

33,0

5

37,4

9

40,9

5

45,3

2

50,6

9

26,1

6

27,4

4

30,2

6

34,9

8

39,3

9

42,0

0

46,0

5

52,8

2

61,5

0

925

1307

1550

1911

2254

2929

3457

4132

5375

1377

1549

1872

2371

3158

3584

4274

5650

7024

25 35 50 70 95 120

150

185

240

115

138

164

199

238

272

306

344

392

92 111

132

161

194

221

249

283

325

42

Tab

le 6

.6E

lect

rical

and

Phy

sica

l Pro

pert

ied

ofS

ingl

e co

re u

narm

oure

d P

VC in

sula

ted

PVC

she

athe

d 60

0/10

00V

cab

les

man

ufac

ture

d to

SA

NS

150

7-3

ST

RA

ND

ED

CO

PP

ER

CO

ND

UC

TO

RS

(/k

m)

W(m

m)

(mm

)(k

g/k

m)

mV

Gro

un

dG

rou

nd

Cu

rren

t R

ati

ng

Cu

rren

t R

ati

ng

Air

Du

ct

Air

mV

(A)

(A)

(A)

(mm

²)(A

)(A

)

Cab

leS

ize

1C

ab

les

AC

or

DC

f

Ele

ctr

ical P

rop

ert

ies

Ph

ysic

al P

rop

ert

ies

Vo

lt D

rop

per

am

pp

er

mV

Vo

lt d

rop

pe

r a

mp

pe

r m

V

No

min

al

Mass

No

min

al D

iam

ete

rs3

Cab

les in

Tre

foil F

orm

ati

on

.f

Imp

e-

dan

ce

25 35 50 70 95 120

150

185

240

300

400

500

630

800

1000

118

156

186

232

281

324

370

424

498

566

651

740

836

931

1041

126

156

191

246

300

349

404

463

549

635

742

835

953

1086

1216

1,75

1,27

0,95

0,67

0,50

0,41

0,35

0,30

0,25

0,23

0,21

0,19

0,18

0,17

0,16

127

153

180

221

265

301

338

381

442

499

565

634

718

792

856

111

132

155

190

226

256

287

323

372

419

472

532

603

689

741

112

141

172

223

273

318

369

424

504

584

679

778

892

1020

1149

1,52

1,10

0,82

0,58

0,43

0,36

0,30

0,26

0,22

0,20

0,18

0,17

0,15

0,15

0,14

0,87

67

0,63

56

0,47

45

0,33

56

0,25

0,20

54

0,17

34

0,14

99

0,12

68

0,11

31

0,10

28

0,09

63

0,08

9

0,85

2

0,08

19

5,95

7,00

8,15

9,79

11,5

4

12,9

6

14,3

9

16,1

0

18,7

1

21,4

5

24,3

0

26,5

1

33,1

5

37,7

0

42,2

5

11,9

1

12,9

6

15,1

5

16,5

7

19,0

4

20,2

4

22,0

7

24,0

8

27,8

1

30,7

5

34,1

0

37,1

3

43,6

2

49,0

0

53,4

5

366

469

632

880

1160

1413

1734

2145

2725

3375

4395

5299

6965

9118

1105

0

D1

D2

Not

e: (1

) D1

is t

he d

iam

eter

ove

r th

e co

nduc

tor .

(2

) D2

is t

he d

iam

eter

ove

r th

e sh

eath

.

43

Tab

le 6

.7E

lect

rical

and

Phy

sica

l Pro

pert

ied

ofS

ingl

e co

re u

narm

oure

d X

LPE

insu

late

d P

VC s

heat

hed

600/

1000

V c

able

s m

anuf

actu

red

to S

AN

S 1

507-

4

ST

RA

ND

ED

CO

PP

ER

CO

ND

UC

TO

RS

(/k

m)

W(m

m)

(mm

)(k

g/k

m)

mV

Gro

un

dG

rou

nd

Cu

rren

t R

ati

ng

Cu

rren

t R

ati

ng

Air

Du

ct

Air

mV

(A)

(A)

(A)

(mm

²)(A

)(A

)

Cab

leS

ize

1C

ab

les

AC

or

DC

f

Ele

ctr

ical P

rop

ert

ies

Ph

ysic

al P

rop

ert

ies

Vo

lt D

rop

per

am

pp

er

mV

Vo

lt d

rop

pe

r a

mp

pe

r m

V

No

min

al

Mass

No

min

al D

iam

ete

rs3

Cab

les in

Tre

foil F

orm

ati

on

.f

Imp

e-

dan

ce

25 35 50 70 95 120

150

185

240

300

400

500

630

800

1000

169

205

245

302

366

422

480

554

656

766

902

1040

1229

1366

1486

174

211

257

236

404

475

542

629

753

881

1045

1182

1417

1603

1790

1,86

6

1,35

2

1,00

7

0,71

0

0,52

6

0,43

1

0,36

3

0,30

9

0,25

9

0,22

9

0,20

7

0,19

2

0,17

8

0,17

1

0,16

6

151

181

213

260

312

355

397

449

522

589

668

750

848

942

1025

137

164

192

235

281

319

356

402

466

524

592

664

746

823

892

137

167

203

257

318

372

426

494

594

692

807

925

1094

1254

1400

1,61

6

1,71

0

0,87

2

0,61

5

0,45

6

0,37

3

0,31

5

0,26

8

0,22

4

0,19

9

0,17

9

0,16

7

0,15

4

0,14

8

0,14

4

0,93

32

0,67

60

5,36

00

0,35

52

0,26

31

0,21

54

0,18

18

0,15

45

0,12

95

0,11

49

0,10

35

0,09

63

0,88

90

0,08

56

0,08

31

5,95

7,00

8,15

9,79

11,5

4

12,9

6

14,3

9

16,1

0

18,7

1

21,4

5

24,3

0

26,5

1

33,1

5

37,7

0

42,2

5

11,8

1

12,8

6

14,3

8

16,2

2

17,9

7

19,3

2

21,4

2

23,6

3

26,6

9

30,0

5

33,3

0

36,3

3

42,7

9

48,8

4

54,2

1

328

426

567

824

1071

1304

1628

1995

2461

3182

4117

5032

6641

8535

1067

6

D1

D2

Not

e: (1

) D1

is t

he d

iam

eter

ove

r th

e co

nduc

tor .

(2

) D2

is t

he d

iam

eter

ove

r th

e sh

eath

.

44

6.3 Derating factors for non-standard conditions

No ofCables

inGroup

Direct in Ground

Axial Spacing (mm)

Touching

In Single Way Ducts

Axial Spacing (mm)

150 300 450 600 Touching 300 450 600

2

3

4

5

6

0,81

0,70

0,63

0,59

0,55

0,90

0,82

0,78

0,75

0,72

0,87

0,78

0,74

0,70

0,67

0,93

0,87

0,85

0,82

0,81

0,91

0,84

0,81

0,78

0,76

0,95

0,90

0,89

0,87

0,86

0,93

0,87

0,86

0,83

0,82

0,96

0,93

0,91

0,90

0,90

0,94

0,90

0,89

0,87

0,86

Table 6.3.3 : Derating factors for grouping of cables in horizontal formation, atstandard depths of laying and in standard soil conditions.Multi-core cables (up to 300 mm²)

Table 6.3.2 : Derating factors for ground thermal resistivity(multicore cables)

Direct in ground In single way ductsThermal Resistivity

(K.m/W)

1,0

1,2

1,5

2,0

2,5

1,08

1,00

0,93

0,83

0,78

1,04

1,00

0,96

0,88

0,87

Depth of laying (mm) Direct in ground In single way ducts

Table 6.3.1 : Derating factors for depth of laying - multicore cables(up to 300mm²)

500

800

1000

1250

1500

2000

1,00

0,97

0,95

0,94

0,93

0,92

1,00

0,97

0,96

0,95

0,94

0,93

45

Note: Cables may be grouped in air without derating, provided that the cablesare installed on ladders, and that for:-

(a)The clearance is greater than 2x the cable overall diameter (or 150mm,whichever is the least).

Horizontal formation

(b)(i) The clearance from a vertical wall is greater than 20 mm, and(ii) The vertical clearance between cables is greater than 150mm.

If the number of cables > 4, they are installed in the horizontal plane.

Vertical formation

Note:

D* is the overall diameter of one cable

Table 6.3.6 : Derating factors for grouping of multicore cable installedhorizontally in air

No. of cables

Condition

Cable touching

Clearance D* between Cables

1

1

1

2

0,9

0,95

3

0,84

0,9

6

0,80

0,88

9

0,75

0,85

Derating Factor

Table 6.3.5 : Air Temperature derating factors

Maximum ConductorTemperature (°C)

70 (PVC)

90 (XLPE)

Air Temperatures (°C)

30

1,00

1,00

35

0,94

0,95

40

0,87

0,89

45

0,79

0,84

Table 6.3.4 : Ground Temperature factors - multicore cables (up to 300 mm²)

Maximum Conductor

Temperature (°C)

70 (PVC)

90 (XLPE)

GroundTemperatures (°C)

25

1,00

1,00

30

0,95

0,96

35

0,90

0,92

40

0,85

0,88

45

0,80

0,82

50

0,70

0,76

Solar Radiation

Correction Factors

1250 /m² (Highveld)W1000 /m² (Coastal)W

Cross-SectionalArea of Conductor

mm²

0,62

0,57

0,53

0,49

0,44

1,5 - 10

16 - 35

50 - 95

120 - 185

240 - 400

0,70

0,68

0,65

0,62

0,59

Table 6.3.7 : Correction factors for direct solar radiation

46

Insulationmaterial

Conductormaterial

OperatingTemperature

°C

Short CircuitTemperature

°CK factor

PVC

PVC

XLPE

XLPE

Copper

Aluminium

Copper

Aluminium

70

70

90

90

160

160

250

250

115

76

143

92

Table 6.9 : Values of conductor/temperature constant K

6.4 Short circuit ratings for PVC and for XLPE insulated 600/1000V cablesto SANS 1507.

With PVC and with XLPE insulated cables, care must be taken to limit theconductor temperature for continuous operation and for short circuitconditions as indicated inTable 6.9.

Short circuit ratings are regarded as internal ratings. Their calculation isbased on an adiabatic equation and is not affected by external consi-deration. Due to unknown variables, short-circuit ratings do not lendthemselves readily to rigid treatment, so whenever possible conservativevalues should be applied.

Ratings are derived from temperature limits as follows:

where = Short circuit rating in ampsK = A constant combining temperature limits and properties

of conductor materialsA = area of conductort = duration of short circuit in seconds

Isc

Isc =

K x A Ampst

7.0 ElastomericTrailing Cables

Features ofAberdare’s trailing cables

The following chapter generally coversType 41 and 61 elastomeric trailingcables. For other elastomeric cables or different voltages please consultour application engineers for specialised technical or installationinformation. The cables described in this section are manufacturedaccording to SANS 1520 part 2 (for greater details see brochure coveringthis product).

Aberdare’s mining trailing cables are manufactured according to SANS1520 part 1 and 2 and bear the SANS mark up to 33 kV. The sheath isreinforced by means of an open-mesh braid in order to limit cut-spread.Theelastomers used for the sheaths are carefully selected to ensure that theproduct will withstand even the highest levels of ultraviolet radiation foundin South Africa.

47

Type 41Trailing Cable

Conductors :

Insulation :

Screens :

Sheath :

RatedVoltage :

Specification :

Tinned soft copperCo-Extrusion of EPM/CSM3 Power cores individually screenedwith copper/textile braid.Pilot core unscreened.Extra-Heavy-Duty CR640/1 100VSANS 1520 Part 1

Self-propelled electrically driven machines, movable electricapparatus in hazardous areas (Minerals Act,1991), typically,• Type 41; 4 mm² for small pumps, drills, fans etc.• Type 41; 10 and 16 mm² for shuttle-cars.

Applications

Type 61A and 61BTrailing Cable

Conductors :

Insulation :

Screens :

Sheath :

Rated Voltage :

Specification :

Tinned soft copperCo-Extrusion of EPM/CSM3 Power cores individually screenedwith copper/textile braid. 3 Pilotcores unscreened..Extra-Heavy-Duty CR640/1 100VSANS 1520 Part 1

Applications

Self-propelled electrically driven machines, portable electric apparatusand movable electric apparatus in hazardous areas (Minerals Act,1991), typically,• Type 61A 25 mm² for LHD's 70 mm² for Shearer and reeling

applications.• Type 61B 70 mm² for Continuous Miners and non-reeling

applications where a lighter cable is required.

48

Tab

le 7

.164

0/1

100V

Trai

ling

Cab

leTe

chni

cal D

ata

(A)

(mm

)(x

PC

D)

(mm

)(

/km

)W

(/k

m)

W(

/km

)W

(kg

/km

)

Cab

le

Siz

e

(mm

²)

Po

we

rP

ow

er

Pil

ot

Pil

ot

4 6 10 16 25 35 50 70 95 16 **35

**50 70 95

**12

0

4 6 10 16 10 10 16 16 16 6 6 6 10 16 16

5,5

3,66

2,11

1,34

0,85

90,

610,

424

0,29

90,

227

1,34

0,61

0,42

0,29

0,22

0,17

5,5

3,66

2,11

1,34

2,26

2,26

1,44

1,44

1,44

3,66

3,66

3,66

2,23

1,44

1,44

3,5

3,6

2,0

1,6

1,1

1,2

1,4

0,7

0,85 1,6

1,2

1,4

0,7

0,85 0,8

7,01

4,67

2,69

1,71 1,1

0,77

80,

553

0,38

70,

301

1,71

0,78

30,

550,

389

0,30

10,

243

45 57 77 100

130

160

200

245

295

105

160

200

245

295

315

25 28 32 33 41 46 51 55 60 31 38 43 48 54 58

27 30 34 36 44 50 55 59 64 33 41 46 52 58 60

0,9

1,4

1,8

2,2

2,9

4,2

5,2

6,2

7,6

2,1

3,3

3,9

5,5

6,9

7,7

8 8 8 8 8 8 8 8 8 8 12 12 12 12 12

150

180

190

200

240

280

300

330

360

185

315

350

390

430

470

Typ

e 4

1Tra

ilin

g c

ab

le (

3xin

d.s

cr.

Po

wer

plu

s 1

x P

ilo

t co

res)

Ty

pe

61

ATra

ilin

g c

ab

le (

3x

ind

.scr.

Po

we

r p

lus 3

x P

ilo

t co

res)

Ty

pe

61

BTra

ilin

g c

ab

le (

3x

ind

.scr.

Po

we

r p

lus 3

x P

ilo

t co

res)

Ma

xim

um

co

nd

ucto

rre

sis

tan

ce

(dc a

t 2

0°C

)

Ma

xim

um

co

mb

ine

dscre

en

resis

tan

ce

(dc a

t 2

0°C

)

Imp

ed

an

ce

( Z

)

Cu

rre

nt

rati

ng

(at

90

°C)

*

Ove

rall

dia

me

ter

min

ma

x

Ca

ble

ma

ss

(ap

pro

x)

Lay

rati

o

Be

nd

ing

rad

ius

(min

)

Ph

ysic

al

Pro

pe

rtie

sE

lectr

ical P

rop

ert

ies

No

te:

1 .L

ow

-Vo

ltag

eTra

ilin

gC

ab

les

with

lay

ratio

so

fm

ore

than

8are

No

tsu

itab

leF

or

Co

ntin

uo

us

Re

elin

g.

* **

Cu

rren

tra

tin

gs

insh

ad

eat

am

bie

nt

tem

pera

ture

of3

0°C

.N

ot

co

vere

db

yS

AN

S1

52

0P

art

1

49

Tested to SANS Test Methods statement 503, 504 and 506

Physical Properties of Sheathing Materials

Property UNITS

MPa

%

N/mm

GP

8

250

5

HD

11

250

7,5

EHD

15

250

10

Tensile Strength (min.)Elongation at Break (min.)Tear Resistance (min.)

Derating Factors for Number of Layers on a Reeling Drum

Number of layers

Factor

1

0,84

2

0,65

3

0,45

Derating Factors for AmbientTemperatures (Mining Cables)

Ambient Temperature (°C)

Factor

25

1,10

30

1,00

35

0,90

40

0,80

45

0,70

Based on an initial conductor temperature at 90°C and a final temperatureof 200°C

1 Second Short-circuit Ratings

Cable Size Current Cable Size Current

(mm² ) (kA) (mm² ) (kA)

16

25

35

50

70

2,0

3,1

4,3

6,1

8,5

95

120

150

185

240

11,6

14,6

18,3

22,6

29,3

8.0 OverheadAluminium Conductors

Aluminium conductors have achieved wide acceptance all over the worldfor use in overhead transmission and distribution lines. Generally a steelcore is used with the aluminium to give the conductor mechanicalstrength. This arrangement is termed Aluminium conductor steelreinforced or ACSR. Conductors comprised entirely of aluminium areknown as All aluminium conductors or AAC. These conductors areextensively used for busbars in outdoor substations where spans areshort. All aluminium alloy conductors or AAAC consist of an alloy ofaluminium to give a tensile strength in excess of that of AAC, allowinglonger spans.These conductors are recommended for coastal areas wheresevere corrosion is a problem.

Hard drawn aluminium in H9 temper is used in both ACSR and AAC. Highstrain steel wire is used in ACSR and this is sometimes protected fromcorrosion by an application of grease. Such measures are particularlyadopted when the conductor is intended for use in aggressive environ-ments as encountered in coastal regions.

Aberdare Cables manufacture a wide range of AAC, ACSR and AAAC tocustomers’ requirements or national specifications. The informationcontained in table 8.2 relates to the more popular sizes and standardsunder the following conditions:

50

Sag and tension charts are available on request. The following informationneeds to be supplied:

• Span length

• Maximum design load (45% of UTS if not specified)

• Stringing temperature.

Ambient Temperature

Maximum Conductor Temperature

Wind Speed

Normal Stringing Temperature

Solar Radiation

Solar Absorption Co-efficient

30°C

75°C

0.44 m/s

25°C

0,089 W/cm²

1

Table 8.1 : Current Rating parameters

51

Tab

le 8

.2P

hysi

cal a

nd E

lect

rical

Dat

a fo

r po

pula

r AC

SR

siz

es

Alu

min

ium

(mm

)(m

m)

(N)

(Am

ps)

(/k

m)

W(m

m²)

Ste

el

Tota

l

Sq

uir

rel

Go

ph

er

Fox

Ferr

et

Rab

bit

Min

k

Har

e

Do

g

Wo

lf

Pan

ther

Bea

r

Go

at

12,9

0

16,3

0

22,5

8

25,8

1

32,2

6

38,7

1

64,5

2

64,5

2

96,7

7

129,

00

161,

30

193,

50

6,33

7,08

8,37

9,00

10,0

5

10,9

8

14,1

6

14,1

5

18,1

3

21,0

0

23,4

5

25,9

7

57,7

0

72,2

0

101

117

145

174

289

289

438

588

733

899

27,5

0

34,4

0

48,1

0

55,6

0

69,4

0

82,8

0

138

100

292

391

488

598

85,2

0

107

149

173

214

257

427

389

730

970

1220

1500

8020

9610

1310

0

1520

0

1850

0

2190

0

3600

0

3470

0

6920

0

9080

0

1120

00

1360

00

1,36

77

1,09

33

0,78

22

0,67

66

0,54

26

0,45

46

0,27

33

0,27

33

0,18

28

0,13

63

0,10

93

0,08

91

130

150

190

210

240

260

360

360

470

560

650

730

6/1/

2,11

6/1/

2,36

6/1/

2,79

6/1/

3,00

6/1/

3,35

6/1/

3,66

6/1/

4,72

6/4,

72+7

/1,5

7

30/7

/2,5

9

30/7

/3,0

0

30/7

/3,3

5

30/7

/3,7

1

Co

de

Nam

e

Eq

uiv

al.

Co

pp

er

Are

a

Sta

nd

ing

/w

ire d

iam

.O

vera

llD

iam

ete

rM

ass (

kg

/km

)U

ltim

ate

ten

sile

str

en

gth

DC

resis

tan

ce

at

20°C

Cu

rren

tra

tin

g

52

9.0 Innovatice Products (INTERDAC 3)

Intermediate voltage 3 phase 4 wire 1900/3300V underground supplycable

Construction

Mechanical forces during installation

(a) Use of intermediateVoltage allows increased power transfer over longdistances with smaller conductor sizes, eg for loads typically 25 kVAthis represents a considerable saving when compared to conventionalsystems.

(b) Underground cable - with a specially adapted tractor, the cable can beburied with minimum labour, and thus least cost.

(c) Screened cable construction for ease of fault location.(d) Buried cable results in a“clean” landscape - no poles or overhead lines

to hinder farm vehicles.

The maximum pulling force that should be applied to the conductor ofINTERDAC 3 Cable during installation is 200 kg.

3 Circular stranded plain soft copper conductors,XLPE insulated, layed up with one circularstranded tinned soft copper earthing conductor,collectively screened with an aluminiumpolyethylene laminate (APL) tape, polyethylenesheathed 1900/3300V underground supply cable.

* DC at 20°C** In ground. Soil temperature 25°C. Depth of lay 500 mm.

Soil thermal resistivity 1,2 K.m/W. Operating temperature 90°C

10

1,83

1,83

2,34

80

0,82

16

1,15

1,15

1,47

105

2,29

25

0,73

0,73

0,93

135

3,57

Cable Size (mm²)

Phase Conductor Resistance*

Earth Conductor Resistance*

Impedance (Z)

Current Rating**

1 Second Short Circuit Rating

( /km)

( /km)

( /km)

(A)

(kA)

W

W

W

Table 9.1 : Electrical properties

Phase Conductor Construction (no. x diam.)

Earth Conductor Construction (no. x diam.)

Insulation Thickness (nominal)

Aluminum Screen Thickness

Sheath Thickness (nominal)

Cable Diameter (nominal)

Approximate Cable Mass

Minimum Bending Radius

Cable Size (mm²) 10

7 x 1,33

7 x 1,33

2,1

0,15

1,45

20,5

545

205

16

7 x 1,67

7 x 1,67

2,2

0,15

1,6

21,3

990

210

25

19 x 1,38

19 x 1,38

2,2

0,15

2,0

26,4

1100

260

(mm)

(mm)

(mm)

(mm)

(mm)

(mm)

(kg/km)

(mm)

Table 9.2 : Physical properties

The Aberdare Group's product range and services are wide but specialised. Tried andtested and carrying South African Bureau of Standards (SABS) marks and complying withInternational Standards, we stand by our products.

• Screened or belted• Fully impregnated or drained• Copper or Aluminium conductors up to400mm² (3 core) & 1000mm² (singlecore)

• Individually screened• Copper or aluminium conductors up to

300mm² (3 core) & 500mm² (single core)

• Flexible Cable (Types H05 RN-F, H07 RN-F)• Welding Cable• Mining Trailing Cable (Up to 33kV)

• AAC (All Aluminium Conductor)• AAAC (All Aluminium Alloy Conductors)• ACSR (Aluminium Conductor Steel

Reinforced)• PHDC (Plain Hard Drawn Copper)

• PVI Panel Flex (Single Core Flexible Wiring)• HRQ Insulated Wire (High Temperature

Insulated Wire 105°C)• Cabtyre (Flexible Wiring)• Ripcord (Flexible Wiring)• Monster (Flexible Wiring)• Illumination (PVC/ Rubber)• PVI House Wire (Single Core General

Purpose)• Flat Twin & Earth (Innovative Wiring)• Surfix (Innovative Wiring)• Submersible Pump Cable (3 & 4 Core

Flexible)

• Nitrile Trailing Cable (Flexible PVC - 4 Core)• PVC Nitrile Cable (Welding)• General Welding Cable (EPM/CM) &

(EPM/CR)

• PVDAC (Low Voltage PVC Cable)• Multicore (Low Voltage PVC Cable)• ABC (Aerial Bundle Conductor)• Airdac SNE (House Service Connecting

Cable)• Airdac II CNE (House Service Connecting

Cable)• Intermediate Voltage Cable (1,9 / 3,3kV)

• Silicone Cabtyre (Flexible Wiring)• Silicone (Single Core Flexible Wiring)• Special Silicone (Polyester & Glass Fibre

Braided Cable)

• RAYCHEM joints and terminations up to132kV

• RAYCHEM heat shrink tubing and mouldedparts

• RAYCHEM wraparound repair sleeves andcable marking systems

• BOWTHORPE surge arrestors• RAYCHEM & ZIBO insulators

(Distribution and Station class)• AMP wedge technology overhead line

connector systems• SIMEL lugs, ferrules and ABC hardware

including torque shear connectors• DULMISON spacers, dampers, heliformed

fittings• DURACAST low voltage cable jointing kits

and resin systems• ABERDARE cast iron joints for PILC cables

POWER

Paper Insulated Cables up to 42 kV

XLPE Insulated Cables up to 66 kV

Elastomeric Insulated Cables

Overhead Aluminium Conductors

GWI (General Wire Insulated)

Electrodac

Silicone

ACCESSORIES

Product RangeOur Services are Wide but Specialised

53

POSSIBLE SPECIFICATION CHANGES:

Aberdare’s policy of continuous product improvement may result in changes to the finished product, the parameters of which may differ fromthe published parameters in this brochure. Aberdare reserves the right to change product specifications from time to time to effectimprovements and / or enhancements and accepts no liability arising from any differences between the published parameters of this brochureand the finished product, unless by prior written agreement.©ABERDARE CABLES (PTY) LTD. Unauthorised duplication by any means strictly prohibited

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