Servo motor load test
How we test a repaired servo motor
Every servo motor we repair is tested at our Chennai bench in the same sequence before dispatch: insulation and hi-pot, winding balance, encoder feedback and commutation, brake, a no-load run, and a full-load run on a custom-built load rig. Measured speed and current are compared with the nameplate, vibration and noise are checked, and the results go on a printed report that travels with the motor.
The test sequence
Each step has to pass before the next one starts. A failure sends the motor back to the bench, not out of the door.
Insulation and hi-pot
Winding-to-frame insulation resistance, then a dielectric withstand test at a voltage set by the motor's rating.
Winding balance
Phase-to-phase resistance and inductance compared for balance.
Feedback and commutation
The encoder or resolver is read on the test system, and the commutation offset is checked against back-EMF.
Brake
Release voltage and holding checked on motors fitted with a brake.
No-load, then full load
A no-load run in both directions, then a run at rated torque on the load rig until temperature settles. Vibration and noise are checked at rated speed.
Why a no-load spin is not enough
A motor with a wrong commutation offset, a weak magnet or a marginal winding can spin quietly with no load. The fault shows up as high current and heat once the axis does real work. That is why every motor is loaded before it leaves.
Our servo motor test system runs motors from many brands without each brand's own drive and reads incremental, absolute and serial encoders, resolvers and Hall sensors. The load rig is built in-house.
The test bench
What the test report shows
Format sample. Values are illustrative and do not come from a customer's motor. Header: serial no. [logged at inward] · fault as received: encoder alarm at power-up, noise at speed · work done: encoder replaced and aligned, bearings and front seal replaced.
| Check run | Acceptance criterion (example) | Measured | Result |
|---|---|---|---|
| Insulation resistance, winding to frame | ≥ 100 MΩ | > 2,000 MΩ | PASS |
| Hi-pot, winding to frame | No breakdown | No breakdown | PASS |
| Winding resistance balance | Within ±3% | 1.12 / 1.13 / 1.12 Ω | PASS |
| Commutation offset | Within ±2° electrical | 0.6° | PASS |
| Brake release | ≤ 90% rated voltage | 19.8 V | PASS |
| No-load current vs nameplate | Within limit | 1.1 A | PASS |
| Full-load temperature rise | Within insulation class | ΔT 38 K | PASS |
| Vibration at rated speed | ≤ 1.8 mm/s | 0.9 mm/s | PASS |
| Released for dispatch | All checks pass | Yes | RELEASED |
See the full sample servo motor test report.
How to send the motor
You can send a servo motor from anywhere in India. Talk to us before you courier, so the unit is expected and logged on arrival.
Send the nameplate
WhatsApp a clear photo of the nameplate, the alarm code and what the machine was doing when it failed.
We confirm repairability
We tell you whether we can test and repair that model before anything is shipped.
Courier or pickup
Courier the motor to our Chennai bench, or ask us to arrange pickup where needed.
Inspection and quote
The motor is opened, inspected and photographed. You get the findings and a quote before work starts.
Repair, test, dispatch
Repaired, run-tested and load-tested, then dispatched with a printed test report.
Do you test every repaired motor under load?
Yes. Every repaired servo motor gets a no-load run and a full-load run before dispatch.
Do you need the original drive to test the motor?
No. Our servo motor test system runs motors from many brands without each brand's own drive.
What does the hi-pot test show?
Whether the winding insulation withstands a high voltage to the frame without breaking down.
Do I get the test results?
Yes. A printed test report travels with the motor.
Can you test to our own acceptance criteria?
Yes. For OEM and plant programmes we can work to your criteria and report format.
Send the nameplate. We confirm repairability before you courier.
WhatsApp a nameplate photo and the alarm code to +91 97866 22233, or email info@starautomations.com.