Technical Audit Report of Electric Loco Sheds, Itarsi ...

of 12 Issued on : 29.03.2016 Report No. RDSO/2016/EL/TAR/0002 Rev ‘0’

Prepared by Checked by Issued by

GOVERNMENT OF INDIA

MINISTRY OF RAILWAYS

Technical Audit Report of Electric Loco Sheds,

Itarsi, Kanpur & Howrah, for maintenance of

Hitachi HS 15250A Traction Motors (TM)

Report No.: RDSO/2016/EL/TAR/0002 Rev ‘0’

Issue Date: 29.03.2016

Approved by

EDSE(Co-Ord) Signature

Issued by

Electrical Directorate Research, Designs and Standards Organisation

Manak Nagar, Lucknow-226011

lR;eso t;rs



Status of Revision

SN. Date of Revision

Page No. Revision Reason for Revision

1. Originally issued in letter form vide letter no.

EL/3.2.172 dated 5.5.2015

2. All 0 Issued in Technical Audit Report Format



Sub: Technical Audit on Maintenance of traction motors type HS 15250A

Ref: Railway Board’s letter number 2007/Elect(TRS)/441/7 dated 11.02.20015

With reference to above, and increase in Hitachi TM failure cases causing punctuality

loss of trains, technical audit has been carried out at ELS/ET, ELS/CNB and ELS/HWH.

RDSO’s observations on maintenance practice being followed by sheds for Hitachi

traction motor HS 15250A are given below:

A: Technical Audit at ELS/ET on 26.02.2015

1.0 Commutator:

Chamfering and V- grooving is not being done on commutator segments after machining,

it may leads to flashing of TM due to accumulation of carbon dust. Shed has informed

that previously ovality and MBTB were not measured at the time of overhaul and Shed

has started these measurements since May 2014

Photo 1: Ready Commutator without chamfering & V- grooving

2.0 Checking of Shunting resistances:

In view of the problem of commutator flashing in WAP4 locomotives, It is advised to

check the resistance of shunting resistances and condition of shunting contactors in all

locomotives on the first available opportunity.

3.0 High wear rate of carbon brushes:

More wear rate on ACPL brushes has been observed compared to Mersen. Chipping and

breakage of carbon brushes have also been observed more on ACPL make.



4.0 Commutator Flashing:

Problem of commutator flashing and high wear rate of carbon brushes are more in WAP4

locomotives based at ELS/ET compare to ELS/CNB & ELS/HWH. ELS/ET is advised to

study the maintenance practices followed by the other Loco Sheds.

5.0 TM lug cracks:

Number of cases of lug crack has been detected by shed. It is advised to continue doing

DPT on TM lugs.

Photo 2 & 3: Lug crack cases

6.0 Storage of grease: In order to prevent contamination and moisture ingress, grease shall be

stored and handled as per RDSO TC No. RDSO/2010/EL/TC/0104- Rev-0.

7.0 Monitoring of TM History & Codal Life:

While reporting/investigating any failure on traction motor, its complete history needs to be

checked. e.g. Manufacturing date of TM, rewinding dates and agency of rewinding,

whether TM has completed its codal life etc. It will help in analysis and establishing the

failure patterns, if any.

8.0 Interaction with other sheds:

Officers and supervisors of the shed should be in regular communication with their

counterparts in other Sheds about the performance of their respective equipments. Majority

of the problems are maintenance related, not design related and regular interaction will help

in overcoming them.



9.0 Implementation of RDSO’s SMI/MS/TCs:

These documents are available on RDSO website. The shed has to evolve a system so that

the section shall have not only copies of all these relevant documents, but their

implementation plan too. This has to be monitored by respective officers & supervisors on

regular basis.

B: Technical Audit at ELS/CNB on 03.03.2015

1.0 TM Cleaning:

ELS/CNB is doing the cleaning of Traction motor by heating stators & armatures in ovens,

followed by blowing & washing by cold water.

As per Hitachi maintenance manual, cleaning of traction motor stator & armature by water

is only recommended when machine has been immersed in flood water or has covered with

sea water.

The Shed is advised to follow the procedure of cleaning of armatures & stators as laid

down in Hitachi Maintenance manual.

2.0 Missing Teflon Band:

Approximately 35 to 40 % traction motors are in service without Teflon band, it is not

correct, it causes accumulation of carbon dust which results in flashing of commutator. Shed

should provide Teflon band on all armatures at the first available opportunity.

3.0 Balance weight:

Excessive balance weight has been noticed on some of the armatures on the shop floor.

Balance weights are tack welded on Armature head & disc spring also.

Welding of balance weights on disc spring is not desirable. In armature no 937-877-12-94

(CLW), V cone was burnt. In this armature balancing weights were welded on disc spring.

It is observed that while welding balance weights on armature, tack welding is used. Tack

welding is sufficient if the balance weight is in balance ring groove. It is not adequate when

welded on other places e.g. armature heads etc. Failures have been reported on traction

motors by falling /Chipping of balance weights and damaging the armature & stators.

Care needs to be taken by the Sheds/ Rewinding Shops that balance weights are welded in

balance ring only.



Photo 4 & 5: Balance weight welded on disc spring

Photo 6: Balance weight welded on arm. head Photo 7: Balance weight welded on disc spring

Photo 8: Balance weight welded on disc spring Photo 9: Broken balance weight welded on hub



4.0 Commutator:

(i) Commutator Profiler is not available with the Shed.

(ii) Carbide tool is used in place of diamond tool for commutator turning.

(iii) V notch cutting on commutator segment is not done

(iv) Commutator Segment damage have been noticed on two finished armatures by

undercutting tool. It is advised to check the correctness of the undercutting Tool.

This type of defect in commutator segments causes chipping and breakage of

carbon brushes, which results in failure and damage of the traction motor.

Photo 10: Commutator segment damaged during under cutting

5.0: Bearing:

Shed is not having SPM meter to monitor the bearing condition. Condition of bearing is

being judged by hearing the noise.

6.0 Finishing Varnishing:

BECKTOL Red finishing varnish is being used on Hitachi TM stators and armatures

instead of recommended finishing varnish TVA 1410. Shed is advised to use

recommended finishing varnish only.

7.0: Armature head crack:

13 cases of armature head cracks were observed by Shed in last one year. These failures

may be due to thermal shock during process of cleaning adopted by ELS/CNB for the

stators and armatures. The Shed is heating the armatures in the oven, followed by

cleaning with cold water jet.



The Shed is advised to follow the procedure of cleaning of armatures & stators as laid

down in Hitachi Maintenance manual.

8.0 Monitoring of TM History & Codal Life: While reporting/investigating any failure on

traction motor, its complete history needs to be checked. e.g. Manufacturing date of TM,

rewinding dates and agency of rewinding, whether TM has completed its codal life etc. It

will help in analysis and establishing the failure patterns, if any.

9.0 Checking of Shunting resistances:

In view of the problem of commutator flashing in WAP4 locomotives, It is advised to

check the resistance of shunting resistances and condition of shunting contactors in all

Locomotives in the first available schedule.

10.0 Interaction with other Sheds:


counterparts in other sheds about the performance of their respective equipments.

Majority of the problems are maintenance related, not design related and regular

interaction will help in overcoming them.


These documents are available on RDSO website. The shed has to evolve a system so

that the section shall have not only copies of all these relevant documents, but their

implementation plan too. This has to be monitored by respective officers & supervisors

on regular basis.

12.0 Current injection set :

Current injection test setup for finding out faulty brazing joints of stator is not available.

This is required to check the brazed joints of stator during AOH/IOH/POH as per SMI no

RDSO/2011/EL/SMI/0271 Rev ‘0’

13.0 Storage of grease:

In order to prevent contamination and moisture ingress, grease shall be stored and

handled as per RDSO TC No. RDSO/2010/EL/TC/0104 (Rev-0).



C: Technical Audit at ELS/HWH on 30.03.2015

1.0 Carbon Brush:

Shed is facing acute shortage of carbon brushes. It is observed that Shed is running the

locos with rejected brushes which were removed from the traction motors in earlier

schedules. This is the main reason of flash over on Hitachi traction motors maintained by

shed. During inspection of removed carbon brushes, it was observed that some carbon

brushes were worn out till the height of pig tail exposing pig tail which results in flashing

of commutator.

It is also observed that due to shortage of carbon brushes, shed is using different grades

and length of carbon brushes (ACPL & Merson) in one traction motor. This is not

correct. It is recommended to use one grade in all brush boxes of a traction motor having

length of individual brushes within prescribed limit.

2.0 Finishing Varnishing:

BECKTOL Red finishing varnish is being used on Hitachi TM stators and armatures

instead of recommended finishing varnish TVA 1410.

3.0 Commutator profiler:

Shed is not having commutator profiler.

4.0 Current injection set :

Current injection test setup for finding out faulty brazing joints of stator is not available.

This is required to check the brazed joints of stator during AOH/IOH/POH as per SMI no

RDSO/2011/EL/SMI/0271 Rev ‘0’

5.0 Bedding stone:

At the time of technical audit, shed was not having bedding stone in section & stock.

6.0 Storage of grease:

In order to prevent contamination and moisture ingress, grease shall be stored and

handled as per RDSO TC No. RDSO/2010/EL/TC/0104- Rev-0.

7.0 Varnishing of brush holders:

It is observed that Shed is varnishing the brush box holders and pin insulators with

BECKTOL Red. It should be stopped with immediate effect. The brush boxes painted

with BECKTOL Red should be cleaned at the first available schedule for maintenance of

the traction motor.



Photo 11: Varnished Brush holders

8.0 Bearing:

(i) Shed is not having SPM meter to monitor the bearing condition. Condition of bearings

is being judged by hearing the noise.

(ii) It is observed that new bearings are stacked in upright position which is not correct.

Photo 12: Bearings Stored in Vertical Condition



9.0 Chamfering & V cutting:

It is observed that chamfering & V cutting have not been done on armatures rewound

from KPA. One armature bearing serial no 423-SAE-308 which is rewound by KPA is

kept in section without chamfering & V cutting.

V cutting on commutator segments has also not done on new armatures of CGL bearing

serial no 2148202-776 SKE-1088 & 2148202-784 SKE 1096 & 2148202-775 SKE 1087

Photo 13: Ready commutator without chamfering & V cut

10.0 Monitoring of TM History & Codal Life:

While reporting/investigating any failure on traction motor, its complete history needs to

be checked. e.g. Manufacturing date of TM, rewinding dates and agency of rewinding,

whether TM has completed its codal life etc. It will help in analysis and establishing the

failure patterns, if any.

11.0 Interaction with other sheds:


counterparts in other sheds about the performance of their respective equipments.

Majority of the problems are maintenance related, not design related and regular

interaction will help in overcoming them.



12.0 Shed is using different fixtures, which is good maintenance practice.

Photo 14 & 15: Fixtures for Brush Holder alignment

Photo 16: Gauge for TM Liner Gap Photo 17: Arc Horn Gap Checking Gauge


These documents are available on RDSO website. The Shed has to evolve a system so that

the section shall have not only copies of all these relevant documents, but their

implementation plan too. This has to be monitored by respective officers & supervisors on

regular basis.

14.0 Mixing of TM grease in gear case oil (Servosyn gear 460RR) in WAP7 locos:

During discussions at shop floor it has come to the notice that approximately one kg

grease (Serovgem-RR-3) is being mixed in gear case of WAP7 locos to thicken the

recommended gear case oil Servosyn gear 460RR .

In this connection, it is advised that intermixing of lubricants is strictly prohibited. This

practice needs to be stopped immediately.

Technical Audit Report of Electric Loco Sheds, Itarsi ...

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