SIGMATEK AKM Servo Motor Replacement and Troubleshooting Guide

Guidelines for Avoiding Pits in Mechanical and Electrical Installation

The process of replacing the motor is not simply a matter of "dismantling the old and installing the new". Mechanical installation deviations and electrical wiring negligence can both lead to serious system failures during the debugging phase.

1. The "invisible killer" of mechanical installation: radial force and axial force

Servo motors are precision equipment, and flanges and shaft ends are easily damaged during installation.

Prohibition of violent installation: When installing couplings, gears, or pulleys, it is absolutely forbidden to use brute force to strike. It is necessary to use the threaded holes provided at the motor shaft end, use appropriate tools for pulling, and heat the driving components as much as possible.

Radial force control: If a sprocket or toothed belt drive is used, it will generate higher radial forces. Excessive radial force can significantly shorten the lifespan of motor bearings. When replacing, it is necessary to consult the technical drawings to ensure that the radial force is within the allowable range. When the force is located at the center of the free axis end, the radial force FR may be 10% higher than the nominal value. For toothed belt drive, the minimum allowable sprocket diameter can be determined by the formula

dmin≥(M0/FR)×two 

d min≥(M 0/F R）Calculate by 2.

Axial force limitation: It is advisable to avoid applying axial loads on the motor shaft as much as possible, as axial loads can significantly reduce the service life of the motor.

Installation direction: For V3 installation (axial), it is necessary to ensure that liquid cannot enter the bearing. For special applications that require packaging, the manufacturer's application department should be consulted.

2. Safety of electrical wiring and EMC protection

Safety first: The wiring work of the motor must be carried out by qualified personnel with electrical technology training. Before wiring, it is necessary to ensure that the equipment is in a voltage free state. Even if the servo amplifier is disconnected from the power supply, the intermediate circuit capacitor may still maintain a dangerous high voltage for up to 5 minutes, and the DC bus voltage must be measured until it drops below 40V before it can be touched.

Shielding and grounding: In order to suppress high-frequency noise, prefabricated shielded cables provided by the manufacturer must be used. Power cables and control cables should be routed as separately as possible (spacing>20cm). The shielding layer must be connected to the shielding terminal or EMV plug with a large area and low impedance at both ends (motor side and amplifier side). Incorrect shielding connection can directly cause EMV noise interference.

Connector matching: AKM motors come standard with angled connectors for power and rotary signals. When replacing, it is necessary to check the number of contacts between the motor and the rotary transformer, and set the number of contacts correctly according to the servo amplifier used. Incorrect settings, especially for small motors, may result in motor damage.

Common troubleshooting and debugging guide

After completing the replacement and installation, various exceptions may be encountered during the initial startup phase. The following is a common troubleshooting guide based on engineering practice.

1. Motor does not spin

This is the most common fault in debugging. The investigation directions include:

The servo amplifier is not enabled (ENABLE signal is not applied).

Set value line interruption.

The motor phase sequence is reversed.

The brake is not released (for motors with brake, check if the 24V power supply is normal and if the brake is ventilated).

The driving mechanical part is stuck. It should be checked and corrected one by one.

2. Run away motor

The uncontrolled high-speed rotation of the motor after starting is usually caused by the reverse phase sequence of the motor. This will completely reverse the polarity of the feedback system. The solution is very simple: simply exchange the power lines of any two-phase motor.

3. Motor vibrations

If the motor produces abnormal vibration during operation, it is usually due to the interruption of the shielding layer of the rotary transformer circuit, which causes interference to the feedback signal. In addition, setting the gain of the servo amplifier too high can also cause oscillation. Solution: Replace the well shielded rotary transformer cable or reset the gain using the default parameters of the motor.

4. Brake error message

The servo system indicates a brake failure, which may be due to a short circuit in the brake voltage supply or damage to the brake itself. When troubleshooting, first check if there is a short circuit in the brake power supply circuit. If the circuit is normal, it may be due to damage to the brake coil inside the motor, and the motor needs to be replaced.

5. Error message output stage error

When an amplifier reports an output stage fault, it usually means that there is a short circuit or ground short circuit in the motor circuit. Troubleshooting steps: First disconnect the motor wire, check if the cable insulation is damaged, and replace the cable; If the cable is normal, it may be due to a short circuit or grounding in the internal winding of the motor, and the motor needs to be replaced.