2eeeeeeee140522 Guide to the selection of PPE against the ...icolim2014.org/2014/ppt/143.pdf ·...

Guide to the selection of PPE against the thermal hazards from electric fault arc according to BGI/GUV-I 5188:

Method and first experiences in use

Martin Mehlem, BG ETEMICOLIM 2014, Budapest

Guide to the selection of PPE against the thermal hazards from electric fault arc according to BGI/GUV-I 5188: Method and first experiences in use

Contents

� Actual situation

� BGI 5188

� Structure

� Scope

� Procedure for the selection of PPE against the thermal hazards

� Information about practical implementation

� Conclusion

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Problem …

22.05.2013Guide to the selection of PPE against the thermal hazards from electric fault arc according to BGI/GUV-I 5188: Method and first experiences in use

Seite 3

CurrentVoltagePowerTripping time

Incident energy in kJ/m²

?


Structure of BGI 5188

1. Scope

2. Definitions

3. Procedure for the selection of PPE

4. Note for the implementation on the basis of real-life examples

1. Information about practical implementation

2. Expamles

Annexes: - Standards and guidelines

- Standards covering PPE against the thermal hazards of electric fault arcs

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1. Scope of BGI 5188

• Guideline for the assessment of the potential thermal hazards caused by arcing faults in electrical work on electrical equipment.

• Live working or working in the vicinity of of live parts of installations > 50 V AC.

• Hazards due to other effects of an arc, eg by pressure, sound or gases are not considered.

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3 Procedure for the selection of PPEDetermination of expected electric arc energy

dS“kUNntk

Power equipmentElectric SystemProtective devices

Working place

Warc = WLB

Electric arc energy expected

Normalized arc power kP

UNnd

S“k

tk

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3 Procedure for the selection of PPEArc current and duration

• In LV constructions the arc current is less than the prospective short-circuit current (up to 50 %)

• Duration of arc burning is determined by protective device

• Use of the switching characteristics with IkLB = 0,5 I3K

=> tLB = tk IkLB

tLB

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3 Procedure for the selection of PPEArc power and -energy

Normalized arc power kP:

0,05 … 0,10MV installations

0,22 … 0,27LV installations

kPVoltage level

0,17Pmax X)R(0,29

k =

Guide values: For „worst-case“ consideration:

k''k3nNP

k''kP

kLBLB

tIU3k

tSk

tPW

⋅⋅⋅⋅=

⋅⋅=

⋅= WLB arc energy

PLB arc power

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3 Procedure for the selection of PPE2. Determining the protection level of the PPE

PPE test levelArc flash protection

class

PPE

Wprot

Equivalent arc energy (protection level)

WarcP = WLBP

Ei0

CalorimeterI

U

t = 500 ms

WLBP

a = 300 mm

Box test setup with Cu and Al elektrodes

Distance of the electrodes: 30 mm

Class 1: W LBP1 = 158 kJ

Class 2: W LBP2 = 318 kJ

a = 300 mmkT

a

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3 Procedure for the selection of PPE Geometry, distance + equivalent arc energy

• Geometry: Transmissionfactor k T

Kind of installation Transmissionfactor of arc energy k T

(very) small-scale installations with side walls, back walls and barriers

1

large-scale installations,limitation mainly by the back wall

1,5 … 1,9

Open facilities without significant limitations of the electrode chamber

2,4

• Distance a: quadratic proportionality

LBP

2

Tprot W300mm

akW ⋅

⋅=

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3 Procedure for the selection of PPEOverview

Working place PPE

Protective devices Electric System Power equipment PPE test levelArc flash protection

classtk UNn S“k d a kT

Electric arc energy expected Equivalent arc energy(protection level)

Warc = WLB Wprot

Normalized arc power kP WLBP

≤

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4.1 Information about practical implementation

• Reduction of the arc burning time• Using a fast-acting work fuse or adjusting the tripping characteristic of a

circuit breaker• Use of a separate arc protection system

• Increase of the working distance

• Reduction of the short-circuit power at the workpla ce by changing the constellation of the power system

ATTENTION !Repeat The calculation method must be repeated for the modified network parameters

• Analyzing with detailed values for an exacter estamination (higher expenditures in calculation)

Possible measures if protective effect of selected PSA for the considered work processes is not sufficient:

t �

a �

Sk“�

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4.1 Information about practical implementation

If, after calculation

Protective effect of the PPE provided is not sufficient

and

there can be no further action to reduce the potential arc energy,

Live working on the installation is not allowed.

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Annex 4.2: Examples

Work location 1

Cable distribution cabinet, outside

Network station

Distribution point

Work location 2Work location 3

Work location 4

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Work location 1

Example 1: Work on a LV distribustion system

Transformer:630 kVA, 20 kV/ 400VShort-circuit voltage uk = 4 %

NH-transformer fuse:630 kVA gTr AC 400 V

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Step 2: Determination of I “k3, R/X

Results of the short-circuit calculation according DIN EN 60909 (VDE 0102):

2,0XR

)95,0c(kA9,20I

)05,1c(kA1,23I''

min3k

''max3k

=

==

==

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Current limiting factor kB under worst-case conditions (LV):kB = 0,5

⇒ Arc current:

⇒ Tripping time of the fust

Step 3: Determination of Electric arc current

kA45,10

kA9,205,0

IkI ''minp3kBkLB

=∗=

∗=

s1,0tt k ==

Transformer 630 kVA

Transformer400 kVA

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Step 4: Electric arc power at the workplace

Short-circuit power at the work place

MVA004,16

kA1,23V4003

IU3S ''max3kNn

''k

=∗∗=

∗∗=

17,0maxP )X/R(29,0k =

kJ2,608

s1,0MVA004,1638,0

tSkW k''kPLB

=∗∗=

∗∗=

Normalized arc power under worst-case conditions

Electric arc energy WLB

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Steps 5 + 6:Working distance and test level for the PPE

Selection of the working distance: a = 300 mmThis corresponds to the minimum distance between a person‘s torso and the frontal area of the opened equipment.

The test levels for PPE under standardised Box test conditions according to DIN EN 61482-1-2 [2] are:

Electric fault arc protection class 1: WLBP1 = 158 kJElectric fault arc protection class 2: WLBP2 = 318 kJ

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Step 7: Transmission factor, equivalent arc energy

When working on low voltage distribution systems in transformer stations, it should be assumed that large-scale installations will be used with spatial limitations primarily due to a rear wall structure. A transmission factor of kT = 1.5 is assumed at this location.

Using a working distance of a = 300 mm, it follows for equivalent arc energy that

WLBä1 = 237 kJ for Electric fault arc protection class 1WLBä2 = 477 kJ for Electric fault arc protection class 2

LBP

2

LBP

2

TLBä Wmm300mm300

5,1Wmm300a

kW ∗

∗=∗

∗=

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Step 8 : Selection of protection class

Electric arc powerWLB= 608,2 kJ

Test level for the PPEWLBä1 = 237 kJ bei Störlichtbogenschutzklasse 1WLBä2 = 477 kJ bei Störlichtbogenschutzklasse 2

Result: W LB > WLBä2:

Measures must be taken acc. to section 4.1or

No live working is allowed

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Summary example 1 (1)

Step Determination Parameter Result ofworst-case examination

Result ofprecisecalculationaccording toliterature

1 Network parameter: Nominal network voltage UNn 400 V 400 V

Equipment geometry: Distance between conductors

d 60 mm 60 mm

2 Short-circuit current calculation I“k3p max 23,1 kA 23,1 kA

I“k3p min 20,9 kA 20,9 kA

R/X 0,2 0,2

3 Current limitation kB 0,5 0,633

Minimum fault current IkLB 10,45 kA 13,23 kA

NH fuse characteristic curve tk 0,1 s 0,045 s

4 Short-circuit power S“k 16 MVA 16 MVA

Normalised arc power kP 0,38 0,338

Electric arc power PLB = kP.S“k PLB 6,1 MW 5,4 MW

Electric arc energy (anticipated value) WLB 608,2 kJ 243,4 kJ

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Step Determination Parameter Result of worst-case examination

Result of precise calculation according to literature

5 Working distance a 300 mm 300 mm

6 Standardised PPE test level WLBPKl1 158 kJ 158 kJ

WLBPKl2 318 kJ 318 kJ

7 Transmission factor: small-scale system kT 1,5 1,5

WLbäKl1 237 kJ 237 kJ


8 Comparison: WLB ≤ WLBä ? 608,2 kJ > 477 kJ 243,4 kJ < 477 kJ

PPE Electric fault arc protection class Take other measures or isolate

Class 2 PPE Electric fault arc protection class

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Example 4: Electrical installation behind a house junction box

• Calculation for a typical configuration behind an NH 63 A gL fuse

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Step Determination Parameter Result ofworst-case examination

Result ofprecisecalculationaccording toliterature

1 Network parameter: Nominal network voltage UNn 400 V 400 V

Equipment geometry: Distance between conductors

d 25 mm 25 mm

2 Short-circuit current calculation I“k3p max 3,4 kA 3,4 kA

I“k3p min 3,0 kA 3,0 kA

R/X 2,0 2,0

3 Current limitation kB 0,5 0,554

Minimum fault current IkLB 1,5 kA 1,66 kA

NH 63 AgL fuse characteristic curve tk 0,04 s 0,04 s

4 Short-circuit power S“k 2,353 MVA 2,353 MVA

Normalised arc power kP 0,26 0,25

Electric arc power PLB = kP.S“k PLB 0,61 MW 0,56 MW

Electric arc energy (anticipated value) WLB 24,5 kJ 22,6 kJ

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Step Determination Parameter

Result of worst-case examination

Result of precise calculation according to literature

5 Working distance a 300 mm 300 mm

6 Standardised PPE test level WLBPKl1 158 kJ 158 kJ

WLBPKl2 318 kJ 318 kJ

7 Transmission factor: small-scale system kT 1 1



8 Comparison: WLB ≤ WLBä ? 24,5 kJ > 158 kJ 22,6 kJ < 158 kJ

PPE Electric fault arc protection class Class 1 Class 1

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As a rule, when working on live equipment or in the vicinity of live components in an Industrial plant electrical i nstallation, basic protection, meaning PPE in the Electric fault arc protection class 1, is sufficient.

First experiences in use (1)


Seite 27

Topic that has often led in practice

to uncertainty, has been taken up

Several working groups to define the

selection process of the PSAgS were

established


Seite 28

Questions

� Upper limit

� Lower limit

� Practical possibilities to reduce the electric arc energy

Comments

�Clear reference to T O P principle:

Technical

Organisational

Personal

�Exemplary operating instructions as an attachment

�Own symbol for this kind of PPE?

�English Translation of the BGI 5188

First experiences in use (2)


Conclusion

The German guideline BGI 5188 for the selection of PPE

against thermal hazards from electric arcs:

• allows an assessment of the risks arising from the thermal

effects of an arc

• based on the-box test method according to DIN EN 61482-1-2

• helps in the selection of appropriate PPE

• shows measures to reduce the risk

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More information ?

Download from the website of BG ETEM: www.bgetem.de Webcode: 11205644


22.05.2013

<= BGI 5188 (German version)

BGI 5188 E (English version) =>Search for „ BGI 5188 E“ in www

Or come to the ISSA information desk in the exhibition of this conference

Thank you for your attention

Martin MehlemBG ETEM, Cologne, Germany Head of the Testing and Certification Body, Electrical EngineeringPhone: +49 221 3778 6300Fax: +49 221 3778 6322E-Mail: mehlem.martin(at)bgetem.deCompany website: www.bgetem.de, webcode: pruefstelle-et


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