[CWP MOTOR-B BREAKDOWN MAINTENANCE REPORT] September 4, 2014

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2014

6 . 6 V M B M R

Date:- 2014

2

EQUIPMENT TAG: CW-M-001-2

INTRODUCTION:

This is Squirrel cage vertical shaft 1650kw motor. Full load rpm is 375/min and efficiency

94.5% at 100% rated load.

SOME MAJOR DATA’S OF CWP MOTOR

SPEED TORQUE AND CURRENT CURVE

Equipment Name: Motor-B Rated kW 1650KW

Motor Type HRQ7 806-76V

Rated Voltage 6600 V

Phase 3 ᶲ

Full load amperes 224.6

Pole 16

RPM 372

Ins. Class F

HZ 50

BRG. (DE/NDE) NU244M/AV12SNT

WT 25 Ton

Date:- 2014

3

BACKGROUND OF THE MOTOR MAINTENANCE The cooling water pump (CWP-B) it was observed after giving start command, plant went to black out cycle. Henceforth, it was noted that there was problem in Motor-B and later by Magger it was come to light that the stator was grounded. Thereafter, for continuation of power generation Motor-A was swapped to Pump-B and plant was back on track. Simultaneously, it was decided to disintegrate the motor for maintenance.

VIBRATION:

Before Maintenance Vibration Data

Date:- 2014

4

0

1

2

3

4

5

1 2 3 4 5 6 7

H, V

, A

(m

m/s

)

Data No.

Motor D/E H

Allowable

Just tolerable

MOTOR D/E V

MOTOR D/E A

Motor NDE H

Motor NDE V

Motor NDE A

Date:- 2014

5

DISASSEMBLY OF MOTOR

� Maintenance of the motor work started after safe isolation.

� Following works have been carried out during the Motor break down

maintenance

� Electrical connection was removed by IC&E team.

� Decoupled and performed alignments check for the motor and pump shaft.

Motor coupling hub and spacer ring total gap was found 9.6mm.

� Then motor was lifted by overhead crane then motor brought to the workshop by

a low bed trailer and dismantling work begins.

� The lock nut and lock pin was removed and found good.

� The coupling hub was supported with 03 nos. of chain block and then removed by

oxy-acetylene heat. (Heat range approx- 80~100 °C)

� The DE Bearing External cover, snap ring, bearing and bearing housing was

dismantled.

� The rotor was pulled out from motor stator by crane.

Motor shifted to ST hall Coupling hub removed from motor shaft

Date:- 2014

6

Motor DE Bearing Rotor Lift form Stator

Rotor turn-over by two overhead crane Internal Fan

FINDINGS

After dismantle of motor, findings are given below:

1. Water droplet found spread over the DE bearing cover

2. Rusted mark noted in the NDE end cover

3. A black spot was found in the V-phase

4. In baroscopic inspection, it was found a sign melting of stator core & bar in

damage point.

Third party was hired to inspect the damage point extensively and to take suggestion for

next course of maintenance. The observation of Rotary service personnel is given below:

1. Damaged was localized and a bar melted in flash point. The core damage is

localized only.

2. Then disconnected the damaged bar and done the megger test of the rest of coils

of V-phase and found normal.

Date:- 2014

7

REPAIR WORKS

For temporary repair, Third party personnel suggested to isolate the damaged bar

and upon management consent the following steps have been taken and noted

below:

1. Disconnected the damaged bar permanently

2. Clean and minor repair has done in the core at damage point and re-insulated the

spoiled area.

3. Again connected the rest of the coil of V-phase and insulated in joining point and

let the joint dry under natural air for 12 hours

4. Then megger again and found result satisfactory and handover mechanical for

assembly.

Flash over at the centre of the Stator core Flash over at the centre of the Stator core

Flash point centre of the rotor Flash point centre of the rotor

Date:- 2014

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Disconnection the flash over coil leads Connection with good coil

ASSEMBLY WORKS.

After finding all the required clearances OK, we had started the pump assembling work. � The Rotor was installed with overhead crane. � Then thrust bearing and thrust collar and lock nut were installed.

Motor Non Drive End Bearing Drawing

Date:- 2014

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Motor DE Bearing Assembly Drawing

� Then external fan coupling was installed by Oxy-Acetylene heating. � DE Roller bearing was instilled. � Then coupling was instilled with the help of oxy-acetylene heat.

� Then alignment and Coupling gap was performed.

Alignment Record and Coupling Gap

PUMP TEST RUN

� After pump test run vibration data was measured and everything found ok. � The Pump had been commissioned successfully on 11/8/2013 around 11:45 hrs. � Vibration was within 1.2 mm/s and Motor Bearing Temperature is DE- 36C, NDE-

60C.

Date:- 2014

10

After maintenance vibration data are as per below:-

COMMENTS:

After maintenance maximum vibration is 1.2 mm/s (RMS) at Motor NDE Horizontal

Position.

0

1

2

3

4

5

1 2 3 4 5 6 7

H, V

, A

(m

m/s

)

Data No.

Motor D/E H

Allowable

Just tolerable

MOTOR D/E V

MOTOR D/E A

Motor NDE H

Motor NDE V

Motor NDE A