Sub: ECC failures:

There have been sporadic incidences of ECC failures due to lack of effective maintenance strategy leading to en route loco failures; recently loco number 16007 failed on 31-01-2015 due to ECC holder connection –ve wire breakage in between junction box to holder. Cause wise ECC failure analysis of last three years is given below:

CAUSE	2012 - 2013		2013 - 2014		2014 - 2015		Total
	L	S	L	S	L	S
Bearing defective/jam	1			1	1	2	5
Holder connecting wire torn/ burnt/soldering failure.	1			1	3	1	6
Foundation bolt drop down/ breakage.		1		1		1	3
Coil connection screw drop down.				1			1
Outer rotor fixing bolt loose.				1			1
Horizontal shaft locking bolt loose.				1			1
Outer drum Lock nut broken.			1				1
Less clearance between outer drum and spider.						1	1
Inner rotor check nut drop down.						1	1
Total	2	1	1	6	4	6	20

Each shed should chalk out an action plan to arrest and fully eliminate ECC related failures. Action to be taken:

Cleaning:  cleaning with dry compressed air at 2-3 kg/cm2 pressure should be done after removing cover over brush holder. Further cleaning by wiping with slightly moist cloth with Orion 77 should be done and final air blowing should be done.

Examination: carefully examine the patina and look for any unusual sign for discoloration, film thickness, sparking etc. Inspect the surface of slip ring for excessive wear, rough or dirty clean and polish with fine sand paper. Wipe the slip ring insulation. Check coil connection for tightness. Look for crack formation in slip ring insulator, If any crack is observed, the slip ring should be replaced by removing ECC. Check the coil connection tightness in ECC operating coil. Check the gap in between Outer drum and inner drum. The tightness of grab screw in between holder and carbon pocket should be checked carefully as excessive tightness will cause low IR and less tightness will result in loose holder pocket.

Critical parameters: Clean the ECC Slip Ring and Record IR and resistance of operating coil. IR of Operating Coil should be more than 10 MΩ and    Operating Coil Value should be in the range of  5.8 - 6.5 Ω

Measure the Radiator Fan RPM and check the slip. If is  slip is more than 5% , then  first clean the ECC inner side of rotor by Orion spray and remove the dust to reduce the slip below 5% otherwise check the copper lining by removing the ECC or check the ECC coil value. The slip rpm is given below:

Sl No	Loco	Right Angle Gear Box Gear Ratio	Engine RPM at 8th Notch	Actual RPM	Maximum Allowable Slip 5%	Minimum Permissible ECC RPM
1	WDG3A	1:1.312	1050	1377	68.85 RPM	1308 RPM
2	WDM2	1:1.312	1000	1312	65.6 RPM	1246 RPM
3	WDS6R	1:1.11	1100	1221	61.05 RPM	1159 RPM

Carbon brush replacement should be done in M4 schedule and condition of released carbon brushed should be carefully jointly examined for uneven wear, rapid wear, sparking crack etc. Necessary corrective measures should be taken on the basis of physical condition of released carbon brushes.

In case of any carbon brush showing above mentioned defects, the corresponding brush holder should be attended for pocket wear, spring tension etc. Pairing of all carbon brush holder should be done in M24 and above schedules for ensuring uniform spring tension.

Run out of slip ring should be checked in M12 and above schedule and in case of high run out ,turning should be done. Mandatory turning of slip ring in M24 and above schedule should be done.

Condition of oil should be checked for sign of metallic particle in blotter test in 30 days schedule.

Condition of lead and soldering of terminals should be checked carefully without exerting excess force. Soldering of terminal should be carefully done in M24 schedule and re-taping should be done.

Fasteners: During overhauling all fasteners of outer drum, spider, gear box and foundation bolts should be checked for worn out and damaged thread and replace if not qualify. Use thread locker at the time of assembly and installation.

Harness: Check ECC harness should neither be in stressed nor over hanged condition. Proper clamping should be ensured.

A feedback on implementation of above actions should be sent within 15 days.