Power ground cases of EMD locos and Action plan.

                   There have been large number of loco failures (eighteen) due to “Power ground Faults”. Three failures (20048, 20014 & 12280) due to power ground failure were in last two months alone.

                  Shed should measure IR value of Power circuit and Control circuit. Power circuit should further be sub-divided in branches and IR value of each branch should be taken. Any fall in value from previous reading or from other loco readings should be wakeup call and reason of drop in IR value should be carefully checked as per check list in each branch in all possible locations systematically. Shed should issue desirable IR value achieved in best 10% of loco) in power circuit and strive to maintain the same during every schedule.

 The detail of failures and action plan as per maintenance schedule is given in annexure. Most of these cases are due to insulation puncture of Traction motor power cables. Special drive should be launched for attending TM cables.

                  Suggested action plan to avoid such failures in near future is given below.

SN	ITEM	Details	Action to take
1	TM phase cable	1. Cable insulation damage inside and at facing point of  rubber cleat (20011 on 8/7/07) (20004 on7/11/07) (20012 on3/5/08) (20000 on 28/7/08) (20015 on 7/11/08) (2000 on 21/11/08) (20017 on 18/2/08) (20051 on 17/4/09) (20014 on 1/2/08) (12064 on 30/6/09) (20079 on 11/8/09) (12064 on 119/09) (12166 on 23/10/09) (12179 on 19/7/09)	1.a. Introduction of soft rubber gasket over       cable inside rubber cleat. 1.b. Proper securing of cables to arrest cable swing        during run.
		2.Cable torn due to excessive lurching (20048 on 23-6-2008)	2.a. Re-arrange cable route and keep    sufficient  cable length so that stretching of cable  does not take place at maximum lurching .  Please ensure that the over length cable does not swing or rub. 2.b. Attention for Bogie and Yaw dampers   to avoid  lurching
		3. Cable insulation rubbed with bolts of TM coupling bracket board. (20014on 1/2/08)	3.a.  One special drive to inspect all such   vulnerable location. 3.b.  Application of suitable cable protection like heat shrinkable sleeve and gasket in such locations.
		4. Un insulated portion of cable joint which is housed inside an umbrella boot over TM coupling bracket board burnt out.  (12064 on 27/7/09)	4.a.  Inspection of umbrella boot for porosity       and other physical damage. 4.b. Replace the boot instead of repairing. 4.c. Cover up all un - insulated terminal  joints inside umbrella boot with self        fusible insulating tape. 4.d. Use sealant at the cable entrance into the umbrella boot to arrest water ingress inside umbrella boot.
2	TCC out put phase cable	1. TCC-2 phase V cable (out put) surface is cable insulator was worn out at the entrance of cable duct inside Central air compartment. (20085 on 7/5/09)	1.a.  Checking of all power cable lay out         and fixtures during commissioning of   new locomotive.  It should be made 360 days schedule checking item. 1.b. One special drive for inspection of         power cables in all critical locations of         all locos.
3	TCC cable TM45RT cable	1. TCC2 cable TM45RT cable insulation cracked behind ECC1 cabinet and power ground occurred when came into contact with rain water. (20014 on 28/6/10)	1.a.  Checking of all cable insulation behind        ECC1 cabinet by removing foot board    of all locos. 1.b.  Air blowing and proper cleaning of        cables of that location. 1.c. Apply sealant in leaky location . 1d. Door locking arrangement of all doors should be properly functional and water should not drip inside.
4	Insulator at the back of L456 reactor	L456 reactor insulator in ECC2 back side of the reactor core damaged due to less gap with wall causing power ground. (20048 on 6/5/2010)	1.a. One special drive for checking of gap        between the reactor and the ECC2 wall in all locos. 1.b Use insulated sheet or nomex paper in between reactor and ECC2 cabinet wall.
5	ECC2 terminal board	1.Rain water entered inside ECC2 and high voltage terminal board grounded. (12280 on 30/6/2010)	1.a. Fabricate and introduce ECC2 cable duct cover for WDG4 locomotives to  restrict water ingress through harness. 1.b. Use RTV sealant at cable entrance for        ECC2.  1.c. Check door gaskets for deformation and .If deformed replace it. 1.d. Ensure the ECC2 bottom drain hole   clean. E) Transfer HV terminal points towards top of the terminal board. F) Spray insulated paint over non insulated area of terminal board including terminal  lugs and posts

                    These instructions should be explained to concerned staffs and supervisors .Shed should create an exhaustive check list and action plan to attend power ground case.         

You are advised to introduce the above maintenance practice immediately and send feed back to HQ regularly.