Repair Report (DC Motor)

Customer Date

Make

Power (Kw)

Frame

Speed (rpm)

Outgoing Photo

Order Number

Job No

Model

Voltage (v)

Winding

Current (A)

Mounting

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

Reported Faults / Customer Observations

Description

Nameplate

Rockwell Automation

12438101

500 v Arm, 300 v Field

Shunt

397 A, Arm, 18.83 A Field

Foot B3

Repeated failure of Drive End bearing 12 -13 months after servicing

EA 052903

250 Hp DC Motor

14 February 2010

Reliance

250 Hp

C4414 ATZ

850 / 2000

60481

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

Incoming Photo Stripdown report

Failure Photo Failure Analysis

Inspection / Test RunTest Run Conformance Check

CommentsHigh amplitude, high frequency vibration velocity and acceleration most noticeable at position 2 (drive end) of the motor. Expectation of drive end bearing damage.

The motor was relatively clean externally, internally there was evidence of carbon dust contamination. A foot was found to be broken on the resolver feedback module and a louvred brushgear cover was damaged. The NDE bearing was in good condition and the lubrication appeared clean. The DE bearing was rough to turn by hand and the lubrication appeared carburised. The NDE bearing housingwas oversize @ 170.035 mm.

The DE bearing was removed, cleaned and dismantled. It was evident from our failure analysis the bearing has suffered electrical current discharge damage. Further photos of the damaged bearing are shown later in this report.

Mechanical Fits & Data

Nominal mm

Up Tol

Lo Tol

Pass Fail

Shaft size

Keyway

Shaft run-out

Pass FailPass FailPass FailPass Fail

Pass Fail

Pass Fail

Pass Fail

Nominal size mm

Up Tol Lo Tol

Pass FailPass FailPass FailPass Fail

Nominal size

Up Tol Lo Tol

Pass FailPass FailPass FailPass Fail

Pass FailBearing Shoulder run-out

Journal Measurements - NDE

Nominal

Up Tol

Lo Tol

Journal Measurements - DE

mm

mm

Bearing Bearing

Fit Fit

8 Point Measurements 8 Point Measurements

8 Point Measurements 8 Point Measurements

Housing Measurements - NDE Housing Measurements - DEEEE

Pass FailBearing Shoulder run-out

Rotor Balance Data

Balance grade G1.0G1.0G1.0G1.0 G2.5G2.5G2.5G2.5

Plane

NDE

DE

Permitted (g) Actual (g) Position (Deg)

Foot Flatness

Motor viewed from above

Comments

Balance grade to ISO 1940/1 : 2003 Part 1

Total Indicated Run-out (TIR)

No of Bars

microns (um)

Commutator Profile TIR ReadingGood > 50 um

Satisfactory > 75 um

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

110

14.76

14.76

110.028 mm

110.012

110.012

110.012

110.012

110.012

110.012

2.99

10.80

232

52

110.010 mm

11

1620.00

0.00

0.00 0.05 0.05

0.05

0.00

0.00 0.00 0.00

0.00

0.00

NDE housing was oversize 170.035 mm on inspection.

110.012

95.015

95.015

95.012

95.015

95.015

95.015

95.012

95.015

95

95.018 mm

95.003 mm

3.6248 "

0.845 "

0.01 mm

170.020

170.020

170.020

170.020

170.020

170.020

170.020

170.020

170

170.025 170.000

200.015

200.015

200.015

200.015

200.015

200.015

200.015

200.015

200

200.028 200.000

110.012

6219 C3 6222 C3

Commutator Profile

Commutator Profile (Blue trace - as received, Red trace - after machining)

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

Electrical Data - Static Test

Winding Resistance

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

Insulation Resistance (IR) V@

Electrical Data - Run TestNo load test

V Voltage - Armature

rpm (CW)Motor Speed

ACurrent - Armature

ACurrent - Fields

Load test

KwMeasured Output Power

Earth leakage V@uA

Ohms

MOhm

Winding Resistance

Insulation Resistance (IR)

V@

Earth leakage V@uA

Ohms

MOhm

V Voltage - Fields

rpm (CCW)Motor Speed

V Voltage - Armature

rpm Motor Speed

ACurrent - Armature

ACurrent - Fields

V Voltage - Fields

Field Circuit Armature Circuit

NmMeasured Output Torque

Repair Details / Service Report

1800

50

1486

The motor was fully stripped down and all mechanical parts were checked for correct fit and tolerance. The NDE bearing housing was found to be oversize 170.035 mm (Tolerance 170.025mm - 170.000mm)The housing was bored, sleeved and machined to 170.020 mm. All mechanical parts were blast cleaned and all interior surfaces were spray painted with an anti-track paint. The windings were cleanedand checked for integrity. All winding temperature control devices were checked for correct function.Thecommutator was profiled before being skimmed, undercut and chamfered. A finished profile was recorded. The armature was dual plane dynamically balanced to an enhanced G1.0 balance grade for low vibration operation. The resolver feedback module was checked for correct function and outputs (2,2v pk vector, 2,2v pk SIN, 2,2 vpk COS) Mechanical repairs were carried out to the resolver foot and louvred brushgear panels. A genuine SKF insulated bearing was fitted to the NDE of the motor (6219 C3 VL0241) A SKF 6222 C3 was fitted to the DE.

The motor was assembled and 16 pairs of new brushed were fitted and bedded in.

The motor was run on our test bed and SKF conformance check results were taken and recorded.

The motor was spray painted and packaged ready for delivery.

999 500

356

1485

15.1

14.6

4.3

3.42 1800

0.013 - 0.014

999 500

7.62

Mechanical Conformance Check Data & Vibration Analysis

Conformance Check

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

Vibration Analysis

CommentsThe final test run show the motor has passed the SKF conformance check. Compared to the initial testrun all vibration levels are within limits for each band.

This motor has been fitted with an insulated bearing fitted on the NDE of the motor. Do not allow any ground connection to be made to this bearing by fitting temperature sensing or other metallic conductors.

Fletcher Moorland Ltd. Elenora Street, Stoke on Trent, ST4 1QGTel - 01782 411021 web - www.fletchermoorland.co.uk

Photo Description

Photo Description

Photo Description

Further Analysis / Information

Frosting evident on the inner raceway of the bearing.

fluting evident on the outer raceway of the bearing.

Evidence of carbonisation of lubricant as found on stripdown, note the fresh lubricant evident on the outer race of the bearing. (this has not entered the bearing and has not been subjected to electrical current discharge.