Power Car Train Maintenance - PRASA Corporate Overhaul Project... · 2010-01-13 · COC –...

Copyright © Transnet Limited

Document Name: Maintenance Instruction – Power Car Train Sets In

Service Maintenance Procedures Ref: PD-PDC-NAT-PROC-0007

Classification: External Use Revision: 2

Document Serial No: 0101 Controlled and Issued by: Configuration Officer (Koedoespoort)

Document Owner: Specialist (Type testing and CI)

Product Development Coaches

Approved by: Principal Engineer


Date: 13 January 2010 Page: 1 of 32

POWER CAR TRAIN SETS

IN- SERVICE MAINTENANCE PROCEDURES

REVISION 2

DATE RELEASED

13 January 2010

Note: If there is no red “CONTROL COPY” stamp in the bottom right hand corner of this page, then this is an uncontrolled copy and should be used with caution.











CHANGE CONTROL

Control Name and Designation Signature Date Compiled Deon Lotter

Specialist Type testing and Continual Improvement Product Development Coaches

Reviewed Jacques Posthumus Product Engineering Specialist Product Development Coaches

Approved Bryan Ballantyne Principal Engineer Product Development Coaches

LIST OF REVISIONS

Rev Date Name Modification 2 13/01/2010 D.M.Lotter Added in Copyright











DISTRIBUTION LIST

Name Email Company Sugen Govender [email protected] Transnet Rail Engineering Kevin Moonsamy [email protected] PRASA Bryan Ballantyne [email protected] Transnet Rail Engineering Peter Stow [email protected] PRASA Gordon Westwood [email protected] Transnet Rail Engineering Deon Lotter [email protected] Transnet Rail Engineering Jacques Posthumus [email protected] Transnet Rail Engineering Jan Corna [email protected] Transnet Rail Engineering











TABLE OF CONTENTS

1.0 SCOPE 2.0 GENERAL 3.0 TERMINOLOGY 4.0 SAFETY 5.0 WORKSHOP AND SERVICE MANUALS 6.0 RESPOSIBILITIES AND DELEGATION OF DUTIES 7.0 PROTECTION OF STAFF ENGAGED IN WORKING ON COACHES

APPENDIX A – PRE- AND POST- TRIP INSPECTION

(I.E. “A” INSPECTION) APPENDIX B – ANNUAL SERVICE APPENDIX C – EARTHING SYSTEM APPENDIX D – FAULT FINDING APPENDIX E – BUS LINE LOAD BALANCING











1.0 SCOPE

This procedure applies to all power car mainline train sets with a mains (400/230V AC 50Hz) electrical power system supplied by a dedicated power car.

2.0 GENERAL

The appendices to this instruction contain information not normally included in workshop and service manuals and are to be used as a guide to the correct procedures to be followed.

3.0 TERMINOLOGY

COC – Certificate Of Compliance as required by SANS 10142 part 1 MCB – Miniature Circuit Breaker Phase, Line or Live – One of the three live wires in a three phase power system. Night load – Circuits only activated after dark. On power car train sets this is the step, vestibule, toilet, shower and corridor lights controlled by a photocell located at the coach end next to the gummy at the distribution board end.

4.0 SAFETY

Due to the nature of the coaches, different equipment on common circuits are located inside as well as on the under frame. Before working on any electrical equipment, switch the applicable isolating switch OFF and apply personal lock to prevent the inadvertent switching ON of circuits being worked on. The electrical system is quite capable of delivering lethal shock, injuries and/or burns. No work will be carried out under Live conditions. If work is to be done on the bus lines, then switch the bus line Main Circuit Breakers OFF in the











power car, close the panel doors and lock with a personal lock to prevent the inadvertent switching ON of breakers while work is being carried out. Maintenance actions are aimed at restoring equipment to its full functioning condition. No alterations or additions may be made to the electrical installation of a coach without the coach being electrically tested and certified on completion of the work as per SANS 10142 part 1. The commencement of additions or alterations invalidates the existing electrical certificate. Note: All electrical points are documented on the COC and any alterations will be immediately evident. A coach without a valid electrical COC is not roadworthy and may not be placed in service. Particular attention must be paid to the Neutral conductor throughout the train set, because the loss of the Neutral conductor will cause major, costly damage to equipment downstream from the break. This is due to the unbalanced nature of the load created by the break/loss of neutral. No protective or safety devices may be removed from a circuit or bypassed. All these devices will be present and functioning correctly before a train set can be placed in service. The noise level inside the power car is detrimental to your hearing – Use the hearing protectors provided in the power car. Due attention must be given to the Earth conductors throughout, as protective devices rely on a proper Earth to give the designed protection. This applies to the coach body - bogie - axle jumpers as well, because the system relies on all steel work (including the rails) to provide an earth path with as little resistance as possible. Note: All Live parts must be inaccessible to the public and other employees at all times. Any live parts must only be accessed with a deliberate action using a tool or a key.











5.0 WORKSHOP AND SERVICE MANUALS This instruction must be read in conjunction with the workshop and service manuals supplied by the relevant manufacturers of electrical equipment. Where inconsistencies arise this instruction must be applied.

6.0 RESPONSIBILITIES AND DELEGATION OF DUTIES

The Depot Maintenance Manager/Supervisor: It is the responsibility of the Depot Maintenance Manager/Supervisor to make sure that staff must only perform functions that they are qualified for. Where tasks are performed by semi or unskilled workers, these tasks must be performed under supervision of a skilled person. It is also the responsibility of the skilled person to make the installation safe before the semi or unskilled person is allowed to commence with the work. The Depot Maintenance Manager/Supervisor must ensure that a suitably qualified electrician certifies a train set as being electrically compliant when any changes to the initial train set consist is performed. Note: This is applicable to both train sets with hard cable connections as well as train sets with inter-coach connectors. All safety instructions such as hearing protectors in the power car must be adhered to. It shall be the responsibility of the Depot Maintenance Manager/Supervisor or any such staff delegated by the supervisor to check the electrical equipment of all coaches that are available at the depot during their shifts and to ensure that the relevant services as detailed in this instruction are carried out on such coaches. Should any problems be experienced while no supervisor is on duty and where the supervisor would normally direct the action to be taken, the staff concerned must use their own initiative, work to this instruction, and as soon as possible thereafter report to the supervisor concerned.











The supervisor shall be responsible for the necessary guidance of his staff in the performance of their duties. With coaches that have been booked off for electrical defects, the supervisor shall ensure that such coaches are also checked for any other defects which may not have been reported, or for any services for which these coaches may be due. All staff: All electrical staff engaged in the maintenance of train-lighting equipment shall acquaint themselves with the contents of this instruction and the appendices to this instruction as well as workshop maintenance and repair manuals pertaining to the equipment on which they have to work. In the case of branch line coaching stock operating away from a major depot where no supervisor is stationed, the technician or technical assistant at the depot shall be responsible for the condition, examination, checking and repair of all coaches held at, or departing from, the depot or section. Where there are no train-lighting staff stationed, the frequency of examination shall be determined by the responsible supervisor who shall ensure that such coaches are properly maintained. As there is no means of providing an emergency supply to a coach that fails in traffic (with the exception of emergency lighting for up to one hour), all staff engaged on train-lighting maintenance must ensure that all equipment examined by them, is in good order and completely reliable.

7.0 PROTECTION OF STAFF ENGAGED IN WORKING ON COACHES It is the responsibility of all staff working on vehicles on running lines or in sidings, to ensure that the necessary protection as laid down under Section IX, paragraph 140 of General Appendix No. 6, (as amended from time to time), is provided at all times. All supervisors must be in possession of General Appendix No. 6 (Sections 8, 9 and 11) which must be available to their staff at all times.











APPENDIX A

PRE- AND POST- TRIP INSPECTION (I.E. “A” INSPECTION)

The pre- and post- trip inspection must be carried out before and at the end of a train journey. On scheduled train sets this will be daily. If a train set is scheduled to depart on the same day that it arrived the post- and pre- trip inspections can be combined into one service. If a train is to stand in the depot overnight between trips, then the post- and pre- trip inspections are two distinct services (this is to ensure the identification of any damage due to theft or vandalism that may have occurred overnight as well as subsequent rectifications before the train set departs).

A1 Preparing a train for the next journey:

Anticipating that there may be faults on the train, it is best that the following be done in good time before the train set is sent out into service:

A1.1 Power car:

Check the power car bus lines on both sides and under frame, to make sure that the bus line inter coach cables are in order and that all connection boxes are closed and locked. Check that the wing and tail lights function correctly and that their batteries are fully charged. Repair any unsafe electrical equipment or wiring to its original certified (COC) condition. If this cannot be done then report to the Supervisor who will decide how to render the installation safe until permanent repairs can be done.

To prepare the power car for a trip do the following:

A1.1.1 Verify the charging of the diesel generating set starting batteries.

A1.1.2 Attend to all faults reported.

A1.1.3 Service diesel engines as indicated in the OEM’s maintenance

manual and as per PD-PDC-NAT-MAN-0003.











A1.1.4 Check the fuel level to make sure that the train has enough fuel to make the

journey to the next refueling point. Often this will be a round trip journey including standing time at the away station. Make sure that there is fuel to spare to cater for train delays as well.(To assist in estimating the fuel required, the fuel consumption can be read of the Deep Sea controller display panel - consumption is given in Litres /hour. Add a few Litres / hour (for additional load in service) and multiply this by the number of hours and add some 50%. This will give the fuel required for the journey. Note: Rather too much than too little.

A1.1.5 Check the power car under frame to make sure that all is in order (no

damage from a previous trip, all fuel tank drain cocks are locked closed, all fuel tank filler caps in place and no fuel leaks, etc.).

A1.1.6 Check and start up both generating sets to make sure that they are both in order and fully serviceable.

A1.1.7 Start the generating set with the lowest running hours and apply power to the

train (see power car operating manual and start-up instructions on the control panel).

A1.1.8 If the following was not already recorded (post- trip) after the previous trip then record it now. If it was recorded, verify the recorded data by comparing with the current data.

(a) Record the Current drawn in each phase in the logbook provided.

(b) Record the phase to Neutral Voltage for each phase in the logbook.

(c) Record the E-N Voltmeter reading in the logbook (this should typically be 1-2 V) Compare the reading with previously recorded readings (they should be close). If there is a large deviation, then it could point to a problem in the making and must be investigated. If this reading exceeds 50V then the train is unsafe and cannot leave the depot until the fault is cleared (See section on fault finding).











(d) Record which engine is running. Equal use of both generating sets must be made to ensure that both sets are serviced simultaneously at the necessary intervals.

(e) Record both engine hours.

(f) Record the power factor.

(g) Record the number and types of coaches in the train set.

(h) Compare the recordings with previous recordings. If the train set composition has remained unchanged, report any large deviations to the supervisor.

(i) The recorded data in the logbook is essential to inform the receiving

depot staff to enable them to make certain decisions regarding any faults en-route, etc.

A1.2 Coaches: With the generating set running, perform the following tasks on all coaches if applicable to the coach type:

A1.2.1 Attend to all faults reported.

A1.2.2 Check all coaches on both sides and under frame, to make sure that the bus line inter coach cables are in order, and that all connection boxes are closed and locked.

A1.2.3 Repair any unsafe electrical equipment or wiring to its original condition.

A1.2.4 Switch ON all circuits in coach distribution board.

A1.2.5 Inspect bus line cables, inter coach jumper cables and end connection boxes for mounting security / damage / theft. Repair or replace as

applicable.











A1.2.6 Inspect all lights for correct operation / damage / vandalism / theft. Repair or replace as applicable.

A1.2.7 Inspect all socket outlets for damage / vandalism / theft. Repair or replace as applicable.

A1.2. Inspect all air conditioners for damage / vandalism / theft. Repair or replace as applicable.

A1.2. Inspect all catering equipment for damage/ vandalism / theft. Repair or replace as applicable.

A1.2.10 Verify correct operation of night load by covering the photocell at the coach-end. Repair/replace as applicable.

A1.2.11 Verify the correct operation of the bypass switch by switching it ON (Note: All the night loads must then be ON). Repair/replace as applicable.

A1.2.12 Verify correct operation of water system by drawing off cold water.

Attend to short cycling by bleeding the system.

A1.2.13 Verify correct operation of the geyser by checking hot water availability.

A1.2.14 Verify correct operation of the air conditioning system. Once a month remove the air filters in the evaporating units and clean.

A1.2.15 Switch ON the wing and tail lights (for both directions of running) and verify correct operation.

A1.2.16 Verify correct operation of wing and tail light battery charging. Leave the

wing and tail light switches in the correct positions for the next trip’s direction of travel.

A1.2.17 Attend to all catering vehicle defects reported.











A2.0 Water systems:

Check inlet and outlet water pressure and replace the filter elements where indicated.

A3.0 Air conditioners:

Inspect all air conditioners for damage. Inspect refrigerant piping for leaks and repair if necessary. Verify proper operation. Attend to indicated fault codes as per OEM’s fault code list.

A4.0 Compartment socket outlets:

Check each compartment socket outlet that the 5A MCB toggle is in order and that the socket outlet shutters are functioning properly. Check that the voltage at each socket is 230V +/- 5%. Operate the MCB and verify that it switches the power On and Off.

A5.0 Shower lights:

The shower light must be a double insulated luminaire as required by SANS 10142. If this light is broken or damaged it must be replaced with a new light that conforms to the same specification.

The integrity of this light must be 100% due to the inherent danger that it can

pose. Check that the diffuser is undamaged and securely fitted. No metal parts to be accessible or visible.

A6.0 Kitchen equipment:

All catering equipment to be in good working order. Inspect all cables, conduits, isolators etc. and repair where necessary.

A7.0 Emergency lights:

Once a month, check all emergency lights for proper operation and record in the power car log book.











(Note: Refer to maintenance regime in SANS 1464 22)

A8.0 Power car diesel tanks:

Drain water from the diesel tanks once a month.











APPENDIX B

ANNUAL SERVICE

The annual electrical service must coincide with the C & W lifting. Perform all the functions of the pre- and post- trip inspection as well as:

B1.0 Distribution boards:

B1.1 Check and re-tighten each electrical connection in every distribution board. Pay

particular attention to the Neutral conductors.

B1.2 Vacuum and blow out each distribution board with compressed air.

B1.3 Check the wire insulation at each connection for overheating.

B1.4 Check all cables (especially where they pass through steel panels) for chafing damage. Apply rubber matting inserts or grommets where required.

B1.5 Check all switchgear mountings for security.

B1.6 Check all Neutral and Earth bars for mounting security.

B1.7 Check operation of Earth Leakage relay by operating the test button.

B1.8 Check for the correct labeling of switchgear as per the legend diagram. B1.9 With all loads in the coach On, measure the temperature of each connection

terminal on every MCB. All the temperatures should be close, but if an elevated temperature is found, then check the connection for tightness. If the connections are tight then measure the current in that circuit. If the current is within limits for the circuit, replace the MCB with a new one.











B1.10 Check all wire ends for signs of overheating. Evidence of the characteristic electrical burn smell must be acted on by finding the source and rectifying the problem.

B1.11 Verify that the DB door closes and latches properly and that the main switch is

accessible at all times.

B1.12 Inspect gland mounting security on the cable as well as on the panel.

B1.13 Ensure that all gland shrouds are fitted in place properly.

B1.14 Inspect for vibration and other damage, especially where cables pass through panels.

B1.15 Where a separate Earth cable runs with the power cable, check that the Earth

cable is properly secured, undamaged and electrically properly connected.

B1.16 Coach end connection boxes:

B1.16.1 Clean out using compressed air.

B1.16.2 Check all electrical connections for tightness.

B1.16.3 Check for vibration damage to power leads.

B1.16.4 Check inter coach cable for damage.

B1.17 Check all bolted and screwed connections for signs of corrosion, especially where different metals are bolted together (such as Brass and Alluminium). Remove any corrosion found on all surfaces using fine emery paper, make good the connection and apply a thin layer of petroleum jelly.

B1.18 Check inter coach cable gland for security of mounting on the cable as well as on

the panels.

B1.19 Check colour coded stand-off insulators for damage and security of mounting.











B1.20 Ensure panel door seal is intact and that the panel cover/door is closed and locked when work is complete. It must only be possible to open the panel with the use of a tool or a key.

B1.21 Check for any signs of water ingress.

B2.0 Lights:

B2.1 Clean all diffusers.

B2.2 Replace all defective fluorescent tubes and/or ballasts.

B2.3 Replace all damaged diffusers with new. No light will be placed in service without a proper diffuser.

B2.4 Check correct functioning of all lights and light switches.

B2.5 The operation of the photocell used to control the public area lighting must be

checked by covering it with a dark cover. This will cause the step and vestibule lights to switch ON. Removal of the cover will cause these lights to switch OFF. Switching the bypass switch ON will again switch these lights ON. Leave the bypass switch in the OFF position.

B3.0 Emergency lights:

NOTE: Emergency lights are wired with a permanent Live sense wire. This wire is Live even when the light switch is OFF. Care to be taken when working on these lights to prevent injury.

B3.1 Check correct operation of emergency lights and record in log book. If the

emergency lights cannot maintain the lighting for the specified time it means the NiCad batteries have lost capacity and must be replaced. Note the installation date of new batteries, Ah ratings and location in the logbook.

B3.2 Replace defective emergency light control gear.











B4.0 Water purifier system:

B4.1 Check the state of filter elements and renew if required.

B4.2 Check for proper operation of the UV tube if fitted and renew if required. NOTE:

Do NOT look directly at the lamp as the eyes will be damaged. B4.3 Check the proper settings of the pressure switch. (Cut-in at 50kPA and cut-out at

90kPA)

B4.4 Check the proper operation of the low level limit switch.

B4.5 Check the pumps and water pipe joints for any leakage.

B4.6 Check the door switch for proper operation. No bridging out permitted.

B4.7 Check all connections for tightness.

B4.8 Check all wiring for damage.

B4.9 Repair all frayed wire ends, damaged insulation etc.

B4.10 Inspect relays and transformer for signs of damaged contacts, overheating etc.

B4.11 Any irrepairable defects that will impact on water quality and/or supply must be reported to the Supervisor immediately.

B4.12 Check proper operation of water pumps.

B4.13 Check proper operation of the water system by drawing off water at all taps

inside the vehicle.

B4.14 Ensure that the enclosure door is properly closed and locked when work is completed. It must only be possible to open the enclosure with the use of a tool or a key.











B4.15 If pump motors have been changed, re-commission the water system as described in the power car trains technical manual.

B5.0 Air conditioners:

B5.1 Check evaporator air filters (clean or renew as applicable if clogged).

B5.2 Clean out condenser core with compressed air.

B5.3 Clean condenser and evaporator fan blades using a damp cloth.

B5.4 Clean out condenser core using steam.

B5.5 Check correct functioning of the unit.

B5.6 Use the diagnostic functions to locate faults if available.

B5.7 Check thermostat setting. (21 Deg C)

B5.8 Check setting of oscillating fins on evaporator unit if applicable (select oscillating mode).

B5.9 Clean out condensation drain pipe(s) using compressed air.

B5.10 Clean out evaporating unit using compressed air.

B5.11 Check the unit for correct functioning.

B6.0 Socket outlets:

B6.1 Check correct polarities of L, N & E pins.

B6.2 Check proper operation of switch.

B6.3 Check operation of Earth Leakage relay with the use of an earth leakage tester.

Record trip value.











B6.4 Ensure that the socket outlet is completely serviceable with functioning shutters,

undamaged switch toggle and properly secured cover plate.

B7.0 All equipment:

B7.1 Check the correct functioning of all equipment.

B7.2 Attend to all defects reported by on-board staff.

B7.3 Remove broken, damaged or vandalized equipment and fit new.

B7.4 If replacement parts are not available in time, and the equipment is not essential for train operation then disconnect and insulate the circuit in question and inform the receiving technical depot as well as the train manager. It is not safe to only switch the MCB of the circuit Off as anyone can switch it back On again. Re-connection of the circuit must only be possible with the use of tools. Before the coach is placed in service all CONNECTED electrical equipment must be safe and functioning properly as envisaged by SANS 10142 part1.

B8.0 Photocells:

Check the correct operation of the photocell on each vehicle by covering the photocell and checking that all the applicable lights switch On.











APPENDIX C

EARTHING SYSTEM

Main line power car train sets use the “IT” system of earthing as prescribed by the Signal department. This system uses a 220 Ohm resistor connected between the Star point and Earth in the power alternator. This resistor limits any earth fault current to 1A so as not to interfere with the signal system in the tracks. In practice 2 x 440 Ohm resistors in parallel are used to give the required 220 Ohm. This is done to give greater reliability (if one resistor fails then the other is still there). These resistors are rated at 250 W each to ensure that they can conduct the 1A continuously without damage. It is important that the integrity of these resistors be checked regularly as all Earth Leakage relays in the train depend on them for proper operation.











APPENDIX D

EARTH FAULT FINDING ON POWER CAR TRAINS

D1.0 Background: Considering the earthing system as discussed in Appendix C the following faults are dealt with: • Phase to earth fault (earth faults) • Phase to Neutral faults • Phase to phase faults. • Loss of Neutral

D2.0 Finding earth faults:

Consider a fault as depicted in the sketch:











Should any phase be shorted to earth (coach body) then the fault current will flow via the 220 Ohm resistor (r1) back to the star point. Therefore, at any time, the integrity of the system can be checked by measuring the voltage between earth (coach body) and Neutral (star point) Vr1. This measurement can be taken at any distribution board in the train. If no voltage appears then it means that no current is flowing in the resistor and the system is clear as far as earth faults are concerned. Should a full 230 V be measured it means that a phase is down to earth somewhere in the train. Remember that because the current is limited to 1A, no MCB’s will trip when an earth fault occurs. If an earth fault should occur on any circuit supplied by an earth leakage relay, the earth leakage will trip as it only needs 25-30mA to trip.











D3.0 Surge arrestors:

Due to their destructive failure modes, it has been decided not to use any Surge arrestors. Because of the excellent Earth existing in trains (Faraday cage) it is also not expected that induced Voltages will be a problem.

D4.0 Phase to phase faults:

Phase to phase faults and phase to Neutral faults should be cleared by the MCB protection. Therefore if an MCB in a coach DB trips then the phase to phase or phase to Neutral fault will be on the load side of that MCB. If the main power bus MCB in the power car trips then the fault can be anywhere on the bus line fed by that MCB. The fault could also be in the cables between the bus line and the coach distribution boards. These are the most difficult faults to find. The best method is:

D4.1 Inspect the power bus line(s) thoroughly. If the fault is visible then proceed with repairs else:

D4.2 Switch off all power from the generating set(s) and lock out. D4.3 Stop the diesel engines. D4.4 Make sure that the power alternator(s) are isolated from the bus line(s). D4.5 Switch off all four pole main MCB’s/Isolators in all coaches (it is important to

isolate the Neutral for Meggering purposes). D4.6 If the fault cannot be seen then section the train:

(a) Disconnect the power bus line(s) approx. halfway down the train. (b) Ensure that all sensitive electronic equipment is isolated from the

supply.

(c) Megger between phases towards both ends of the train.











(d) The fault direction should be evident towards one direction from the

Megger readings.

(e) Section this half of the train and repeat Meggering.

(f) Keep on sectioning until the fault is isolated to one coach.

(g) The fault is more likely to be:

• At cable glands.

• Where a non armoured cable is fed through holes in steel plate.

• At connection terminals.

• At chafing points where the bogies could chafe the cable.

• Inter coach bus line couplings or sockets.

• Thoroughly inspect the power bus line(s) as well as the cable

feeding the coach DB from the bus line.

D4.7 If the fault is inside the cable and not visible from outside (rarely found) then the following courses of action can be taken and will vary from case to case:

(a) The fault may be found by means of a fault locator.

(b) For reliability in the long term it may well be better to replace the

complete bus cable on this coach (+/- 24m) if circumstances allow.

Acceptable insulation resistance readings are > 1 M Ohm (preferably >5M Ohm).











D5.0 Neutral faults:

When measuring the voltage between phase to neutral and a reading is much more or much less than the nominal expected voltage, or voltages that should be very close show a large discrepancy, then it points to the possibility that the neutral wire has gone open circuit somewhere.

D6.0 Phase to Neutral:

If you are measuring from phases to neutral the three readings should all be very close to each other and in the region of 220 – 230 V. If you get something like the following readings:

R – N = 215V W – N = 245V B – N = 233V The readings point to a floating neutral ie the neutral is not connected to the star point on the alternator.

D7.0 Corrective actions: D7.1 Start at the point of supply.

D7.2 Measure phase to neutral voltages.

D7.3 If measurements are OK as described above then go to next coach and

repeat measurements.

D7.4 As soon as the readings show a large discrepancy then the fault lies in the area between the current and the previous readings.

D7.5 Inspect the main supply cables in this area for:

(a) Loose connections. (b) Faulty MCB’s (c) Cable damage.











D8.0 Loss of Neutral:

Due to the nature of the installation and the connected loads, it is very difficult to keep the phase balancing correct at all times. The consequence of this is that at times, should the Neutral break, instead of having the same phase Voltage to Neutral, the system will develop quite different phase Voltages to Neutral. These Voltages are dependant on the load on each Phase. Consider the sketch:











D8.1 If a break in the Neutral should occur at point A:

In Fig.1 it is clear that the same Voltages will appear across the three loads because the three loads are identical. In Fig. 2 the Voltages appearing across the three loads will each be different from the other because the three loads are all different. The highest Voltage will appear across the smallest load (in this case Load 3) The problem is that whereas Load 3 is rated to work at 230 V the Voltage may escalate to 270V or even higher. It all depends on the loads. In this case all the loads in the train that make up Load 3 will suffer damage due to the elevated applied Voltage. Therefore note the following:

D8.1.1 If a train has reported that in various coaches there are different equipment mal functions then it points to a loss of the Neutral. If the equipment is inspected and blown electronic boards or that tell tale smell of electrical overheating is evident then it is quite sure that the Neutral was lost.

D8.1.2 Due to the massive damage caused by this type of fault the integrity of the

Neutral must be checked at every opportunity. D8.1.3 Even finding that distinctive electrical burn smell in one equipment points to

overloading caused by the loss of the Neutral. D8.1.4 The closer the break in the Neutral occurs to the power car the more damage

will be in the train. Therefore checking the integrity of the Neutral from power car to the last coach cannot be stressed enough.

D8.1.5 Measuring the current in the Neutral conductor is also an indicator of how

bad the damage will be should the Neutral be lost. The higher the Neutral current the more the damage. The lower the Neutral current, the better the load is balanced.

D9.0 Points to note during fault finding: D9.1 It is easy to get flustered, and then go on a wild goose chase – do not allow

this to happen. Remember that most faults are located by a process of











eliminating the “good” equipment. Stay focused, WORK METHODICALLY, ALWAYS i.e. if one light is dead, measure for Voltage at that light, then at the switch, then at the light’s MCB in the DB etc working back towards the point of supply (the DB) until the Voltage is correct. The fault will be found between this and the previous point of measurement.

D9.2 Do not take things for granted – an MCB or a switch can be defective inside,

so if there is Voltage at the top, do not assume that there will be Voltage at the bottom if the MCB or switch is ON, MEASURE.

D9.3 ALWAYS WORK SAFELY – If the power is Off due to a fault, don’t take a

chance, switch the main MCB OFF, measure to ensure there is no Voltage before working.

D9.4 If you cannot see the main MCB from where you are working, then lock the MCB in the OFF position to prevent someone else switching it ON while you

are working. D9.5 The system has been designed to make fault finding easier. Every coach

distribution board has a four pole main MCB and/or Isolator. This makes it possible to electrically isolate a coach completely from the supply. Therefore you can be sure that any measurements taken on an isolated coach reflect only what happens on that coach and cannot be affected by other coaches.

D9.6 Remember that every DB that supplies circuits on Earth Leakage will have

two Neutral bars – one for the E/L circuits and one for the other circuits. DO NOT SWAP A NEUTRAL WIRE FROM ONE NEUTRAL BAR TO THE OTHER – this will not solve anything and will make the fault finding task much harder. Find the real fault.

D9.7 If a circuit is found with a short circuit and the fault cannot be repaired in time,

then isolate that circuit by disconnecting and insulating the loose wire. DO NOT JUST SWITCH THE MCB OFF – SOMEONE ELSE WILL SWITCH IT BACK ON. Remember to notify the operator as well as the destination depot. Repair the fault at the earliest opportunity.











D9.8 Be careful with Meggering, various equipment in the trains have sensitive electronic equipment installed that will be destroyed by Megger Voltages. If in doubt rather isolate the equipment before Meggering.

D9.9 Consider the nature of the fault – open or short circuit. These two faults are normally indicated by a protective device (MCB) tripping in the case of a short circuit and equipment just not working (with all switches and MCB’s On) in the case of an open circuit. In the case of an open circuit remember that some equipment have built-in protection (fuses) that may have opened.

D9.10 If a fault is found ALWAYS find the CAUSE before the fault is corrected. If the

cause is not removed /repaired etc. the fault will occur again. Sometimes these faults are due to oversights in design. Whatever the case, the cause must be addressed.

D9.11 NEVER correct a fault by bypassing protective devices or just by increasing

their rating (do not replace a 10 A fuse with a 20 A fuse etc.). D9.12 NEVER restrict the operability of a device (do not jam a contactor in the

closed position etc.) Remember that sometimes protection devices are wired in the coil circuit and so relies on the contactor to break the main circuit on fault condition. Doing this will also be viewed in a very serious light.











APPENDIX E

BUS LINE LOAD BALANCING

If coaches have been removed from or added to a set, the following must be done: Once all the bus line cables have been connected and the couplers locked, start the generator and apply the power to the train. Make sure that all circuits in the train are ON. Take Ammeter readings of each phase of both bus lines. Ideally both bus lines should share the load equally. If there is a marked difference between the bus lines, then switch coach by coach over to the bus line with the lowest load until a better balance is reached. The readings will probably never be quite equal but it should be possible to get the bus lines to within 80% of each other. Keep in mind during this exercise what the situation is in the kitchen car. If the catering equipment is not ON then the bus line feeding the kitchen car should run at a reduced load to the other bus line to allow for the kitchen equipment that will switch ON later.

Power Car Train Maintenance - PRASA Corporate Overhaul Project... · 2010-01-13 · COC –...

Documents

Transcript of Power Car Train Maintenance - PRASA Corporate Overhaul Project... · 2010-01-13 · COC –...