How to Test a Servo Motor

Testing a servo motor can seem like a complicated, confusing and somewhat overwhelming task. However, with the right tools (ohm meter or megaohm) and the necessary knowledge, the process is a simple and straightforward one to follow. By breaking the servo motor testing process down into achievable steps, testing a servo motor can be quite simple and basic.

FIRST, BE SURE TO DISCONNECT ALL POWER TO YOUR SERVO MOTOR

Servo Motor Test for a Short with a Megaohm Meter

One of the easiest ways to test and troubleshoot a servo motor is by looking for any short or open circuits that exist within the system by testing all three wires (T1, T2, T3) to the ground wire with a megaohm meter.

  • Place the positive lead onto T1 and the negative lead to ground. Go back and repeat these steps forT2 and T3.
  • Make sure the leads on both ends are not touching anything else, including other leads.
  • Each phase should measure between 600 to 2,000 megaohms.
  • If the resistance reading is 0 or shows a low resistance (20 and under), you likely have a short in your system.

Servo Motor Test for a Short with a Ohm Meter

An ohmmeter is an electrical testing tool that measures electrical resistance. By using this tool you can test for a short in your Servo Motor.

  • Start by disconnecting lines T1, T2 and T3 from the drive.
  • Using your Ohm Meter, begin by testing while the cable is still connected to the servo motor.
  • If the reading on your Ohm Meter is 0, you likely have a short in your servo motor.
  • Next, disconnect the cable and test the servo motor and cable alone.
  • Make sure the leads on both ends are not touching anything else, including other leads.

Servo Motor Test for an Open Circuit or Short Between Phases

One of the easiest ways to test and troubleshoot a servo motor is by looking for any short or open circuits that exist within the system by testing all three wires (T1, T2, T3) to the ground wire with a megaohm meter.

  • Start by testing the connections between T1 to T2, T2 to T3 and then bac to T1 to T3.
  • You can expect to see a range between 0.3 and 2.0 ohms with 0.8 ohms being the avg.
  • If you get a reading of 0 there is a short between the phases.

If you get a reading of infinite or 2000 ohms and above, it is an open short.