Servo Motor Testing

How do you know if a servo motor will function correctly after a repair?

Servo motor testing is something we take very seriously at Fletcher Moorland.

We know there is not just one method or piece of test equipment that can verify the repair of a servo motor. We have invested heavily in off the shelf equipment and designed our own equipment to ensure we can test and load test a servo motor.

It’s important that a servo motor is load tested after a repair. We have located faults on servo motors under load that have passed every other test.

Our own designed and built method of load testing involves driving the repaired motor against another servo motor that is acting as the load.

The servo motor providing the load is linked to a motion controller that can automatically adjust the load as required.

The control for our load test station is via a touch screen controller that is linked to our job tracking and recording software.

We carry out two load tests on our repairs

The first is to run the motor (with its own drive) at maximum speed and then increase the load in increments to full load, this is done both clock and counter clockwise.

The second test is to set full load at the motor shaft and to increase the speed in increments from zero to full speed, this is also done in both directions. We can also add a soak test load profile to match the conditions that would be seen on a robot or a machine tool.

The current drawn per phase is recorded and compared. This test ensures the motor can handle the load and it also checks the magnet strength at operating temperature. Our load test station also checks the brake holding torque and breakaway torque.

Servo Motor Testing

Click to Enlarge

Mitchell TI3000 & TI5000EX

There are off the shelf pieces of equipment that can help in servo motor testing. We have bought the complete and fully loaded versions of the Mitchell TI5000EX encoder tester and the TI3000 motor tester. These are not adapted to load testing servo motors but are a tool to help in the repair process.

Universal Test Area

We have invested in a number of drives and applications along with in-depth OEM training for our engineers. This gives us the ability to test a number of generic encoder, and resolver type servo motors. The motors are firstly tested for operation under no load and are then transferred to our load station for final verification.

OEM Specific Test Area

Over the years we have invested in a number of OEM specific drive combinations to run servo motors. These are equivalent to single axis units i.e. PSU/Drive/Motor combinations. We run specific motors with the required drive to check the repair. The motor is then linked to our load test for final load test verification.