Analysis of common faults of servo motors

For more details, please check EASYCNC YouTube video here.

Analysis of common faults of servo motors
 

First, the motor overcurrent overload alarm
1. The motor is improperly installed or the mechanical load is too large, resulting in overload alarm.

Solution: Install correctly, reduce mechanical load or replace the high-torque motor.

2. Water ingress of the motor.

The motor stator coil is less than 10MΩ insulated to ground, and the power socket is short-circuited between phases.

Solution: Cleaning and drying stator insulation resistance should be greater than 100MΩ, if the requirements are not met, replace the power socket or motor stator.

This is due to poor waterproof treatment, which causes a large amount of cutting fluid to enter the motor, so that the motor insulation layer is damaged and the ground is short-circuited. Previous article:FANUC motor is flooded, how to measure? 

3. When the user replaces the encoder by himself, he forgets to install the coupling or the encoder detects errors. Causes an alarm. Solution: Replace the encoder or coupling with a new one.

Second, the motor overheating alarm (430 alarm)

1. Due to poor waterproof treatment, a large amount of cutting fluid enters the motor, so that the motor insulation layer is damaged and the ground is short-circuited.

2. The temperature sensor detects the error and the temperature sensor is damaged. The normal value should be between 55-80kΩ, and the resistance value varies with ambient temperature. Solution Method: Send the motor back to the company for repair;

3. Improper installation of the motor and excessive mechanical load cause overheating alarm. The solution should be installed correctly to reduce the mechanical load;

4. Motor brake coil with brake short circuit or open circuit. The brakes are not open, causing excessive load on the motor. The reason is due to the imprecise voltage capacity supplied to the brake coil. The brakes do not open completely. Solution: Replace the brake and have a separate power supply. α series electric mechanism The coil resistance value of the actuator is about 230Ω, and the coil voltage is 90V. αi series motor brake coil resistance 26Ω, coil voltage is 24V.

3. The motor coil is bad

Servo motor power line:

A---U (drive side) B---V (drive side)

C---W (drive side) D---G (ground side)

Motor coil diagnostics:

Measured with a megohmmeter 500V

Good: >100MΩ

Start aging: 10~100MΩ

Severe aging: 1~10MΩ

Faulty: less than 1MΩ

4. The motor holding brake is broken

Why is the motor holding brake easy to break?  The servo axis controlled by the holding brake is basically the gravity axis, the Z axis of Lijia, and the X axis of the lathe, so the load is generally relatively large, and the large load for a long time is easy to make the motor hot, and at high temperature, the hot wear plate is easy to wear, so that after a few years, the holding brake fails, and it falls down during the emergency stop.