Permanent magnet servomotor has 3 phases and ground. Some standard servomotors also have reactive equipment, such as incremental encoders (with Hall sensors), absolute encoders or resolvers. The reaction cable may be part of or separate from the motor power cable.
If the motor is connected to the servo driver, shut off the power supply to the driver. Follow the manufacturer's claim to get the time the drive dissipates voltage. Disconnect the motor phase and ground wires from the driver. (Please note the connection so that you can connect from the beginning after the test.) These standard lines are larger than the reaction lines. No need to disconnect the reaction line from the drive.
Use the ohmmeter to check the resistance between the three motor phases (1-2, 2-3, 1-3). Different manufacturers use different names for their motor phases (UVW, XYZ, 1-2-3, ABC), but for this test, it is arbitrary. These should measure the same resistance between the phases of the motor. Typical values are less than 20 ohms.
Also check the resistance between the motor phase and the ground wire. These should measure infinite resistance.
If the motor is short-circuited in phase (near resistance 0) or short-circuited in ground, it is necessary to replace or repair the motor. This condition can cause problems with the servo drive. You can view the servo drive and display an error log if it is a newer digital drive. Older drivers may have fault indicators that may indicate motor problems, overcurrent/bridge/I2T problems, or other problems.
Is the motor out of phase?
In general, if the servo motor is stuck in the machine, one particular motor phase will flow more current than the other two phases and will short out before the other two phases. In the future, you will be able to lower the current on the drive to avoid overcurrent of the motor. Almost all of our motors have a thermistor or thermistor that disconnects when the motor gets hot and helps to avoid overcurrent in the motor. Check whether the drive is connected. It is standard equipment for Pike drivers and cables. The driver also monitors the continuous current and peak current flowing to the motor and has limited it to the motor rating. However, if the control power is reset on the drive and the motor has cooled enough to make the thermal opening and closing, the maintenance function may be destroyed; Otherwise, it may damage the maintenance function. Use a driver to control the power supply or keep it active to avoid overcurrent. If the motor is maintained by relying on its thermal switch, limit the driver's peak current to twice the motor's connection current rating. Motor current rating is also based on assumed ambient temperature. If the ambient temperature is very high, the current is required to drop.
Are all three motor phases short-circuited?
It is unusual for a servo motor to short-circuit in all three phases. In this condition, when the motor is running, the driver sends too much current across all three phases. Check that the motor is properly equipped for the drive and that the current Settings conform to the motor rating. Check the ambient temperature of the motor according to the rated current of the motor. If the ambient temperature is high, it is necessary to lower the motor rating and adjust the driver current setting. Otherwise, it is required to use cooling on motors (electric fans or blowers, cold plates or larger radiators).