SAMPLE FORMAT · ILLUSTRATIVE VALUES · NOT A CUSTOMER RECORD
Servo Motor Test ReportRefurbishment and repair-return · Chennai servo bench
1Customer and job
Customer[Redacted]
Customer ref. / PO[Redacted]
ProgrammePlant repair-return
Received[DATE]
Dispatched[DATE]
PriorityLine-down
2Unit identification
TypeAC servo motor, permanent magnet
Make / model[Redacted]
Serial no.[Redacted] · logged at inward
Rated output1.5 kW
Rated speed3,000 rpm
Rated torque / current4.8 N·m / 9.2 A
FeedbackSerial absolute encoder
Brake24 V DC holding brake
3Inward inspection and complaint
Reported faultEncoder alarm at power-up; noise at speed
Housing and shaftNo damage. Keyway OK
SealsFront oil seal worn, oil traces inside
ConnectorsFeedback connector contaminated
Inward photos6 photos on file
4Findings and work done
| Item | Finding | Action |
|---|---|---|
| Encoder | No serial communication | Replaced with equivalent. Commutation offset aligned |
| Bearings | Front bearing noisy | Front and rear bearings replaced |
| Front oil seal | Worn, allowing oil ingress | Replaced. Interior cleaned |
| Brake | Releases and holds | Tested. No action |
| Windings | Insulation, hi-pot and balance within limits | No action |
| Feedback connector | Contaminated | Cleaned and re-tested |
5Test results
| # | Test | Method | Acceptance criterion (example) | Measured | Result |
|---|---|---|---|---|---|
| 5.1 | Insulation resistance, winding to frame | 500 V DC insulation tester | ≥ 100 MΩ | > 2,000 MΩ | PASS |
| 5.2 | Dielectric withstand (hi-pot), winding to frame | AC hi-pot tester, 60 s, voltage per OEM specification | No breakdown; leakage below set limit | 1,500 V AC · 1.2 mA | PASS |
| 5.3 | Winding resistance, U-V / V-W / W-U | 4-wire milliohm meter, corrected to 20 °C | Balance within ±3% | 1.12 / 1.13 / 1.12 Ω | PASS |
| 5.4 | Winding inductance balance | LCR meter, 1 kHz | Balance within ±5% | 4.6 / 4.7 / 4.6 mH | PASS |
| 5.5 | Back-EMF constant, line to line | Motor driven at constant speed | Within ±5% of rated | +1.2% of rated | PASS |
| 5.6 | Encoder communication and position | Universal servo test system, full rotation | No communication errors; position consistent | 0 errors | PASS |
| 5.7 | Commutation offset | Electrical angle against back-EMF | Within ±2° electrical | 0.6° | PASS |
| 5.8 | Holding brake | Release voltage and holding check | Releases at ≤ 90% rated voltage; holds rated torque | Releases at 19.8 V | PASS |
| 5.9 | No-load run test | Universal servo drive, rated speed, both directions | Smooth rotation; current within limit | 1.1 A | PASS |
| 5.10 | Load test | Custom-built load rig, rated torque until temperature is stable | Temperature rise within insulation class limit | ΔT 38 K | PASS |
| 5.11 | Vibration | Velocity, RMS, at rated speed | ≤ 1.8 mm/s | 0.9 mm/s | PASS |
| 5.12 | Shaft runout | Dial gauge at shaft end | ≤ 0.02 mm | 0.01 mm | PASS |
6Result and failure feedback
PASS
Root cause. Worn front oil seal let oil reach the encoder and the feedback connector, causing the encoder failure.
Recommendation. Check oil or coolant spray at the motor's mounting position. Inspect the seal at the next planned maintenance.
7Traceability and sign-off
Parts replacedEncoder, 2 bearings, oil seal · part and lot nos. on file
Test instrumentsCalibrated · IDs and due dates on file
WarrantyAs stated on the quotation
Tested by[Name] · Test engineer
Checked by[Name] · Quality
Date[DATE]