600

Power off the machine completely and lockout. Disconnect the motor power cables (U, V, W) from the amplifier at the servo amplifier terminal block to isolate the motor from the drive.

Ensure all power is removed and capacitors have discharged (wait 5 minutes minimum) before touching any electrical connections.

Using a megohm meter (insulation tester), test motor winding insulation at 500VDC. Test each phase (U, V, W) to motor frame ground and phase-to-phase resistance. Acceptable insulation resistance should exceed 10 megohms. Also measure phase-to-phase winding resistance with a multimeter - all three pairs should be equal within 5%. Typical servo motor winding resistance is 0.5-5 ohms depending on motor size.

Inspect motor power cable routing for pinch points, sharp bends near cable tracks, or damage to cable jacket. Check cable gland entry points at motor and amplifier for chafing. Replace motor power cables if any damage is visible or if cable has been in service over 5 years in high-flex applications.

If motor insulation test fails or winding resistance is unbalanced, replace the servo motor. If motor tests good, reconnect motor cables with proper torque specifications and proceed to check amplifier power module.

With machine powered off and motor disconnected, observe the amplifier LED display. Check for LED codes indicating power module failure. On Alpha-i servo amplifiers, a red LED or specific fault code pattern indicates IPM fault. Record the axis number (n) shown in the alarm - this identifies which amplifier axis module failed.

Navigate to DIAGNOSIS > SERVO screen (or press SYSTEM > DIAGNOSTIC and select servo displays). Check diagnostic numbers 200-207 (servo alarm history) and 300 (current feedback monitor). If current spikes are visible even with motor disconnected when attempting restart, the power module is internally shorted.

Check diagnostic 380-387 (regenerative load factor) and 391 (DC link voltage). Normal DC link voltage is approximately 280-320VDC on 200V class systems, 530-680VDC on 400V class. If DC link voltage drops immediately to zero or shows erratic readings, the DC bus capacitor or power module is faulty.

Replace the servo amplifier axis module (single axis card) or entire amplifier unit if integrated type. After replacement, verify parameter 2020 (motor serial number) and parameters 2022-2024 (motor specification code) match the connected motor. Execute amplifier ID verification and perform current offset adjustment using the setup procedure in MAINTENANCE > SERVO > OFFSET.

Replacement amplifiers must match system voltage class and current rating. Always update amplifier serial number in parameter 2033 after replacement.

Navigate to SYSTEM > PARAM and verify axis servo parameters. Check parameter 2020 (motor model selection code), parameter 2021 (motor combination number), and parameter 2023 (maximum current). Cross-reference these values against the motor nameplate to ensure proper motor type is configured. Incorrect motor selection causes mismatched current control.

Check parameter 2010 (speed loop gain), parameter 2011 (speed loop integral time constant), and parameter 2013 (position loop gain). Excessive gains can cause oscillation and current spikes. For troubleshooting, reduce parameter 2010 to 50% of current value and parameter 2013 to 30 (from typical 80-120) to verify if overcurrent clears.

Document original parameter values before changes. Reduced gains will affect machining accuracy temporarily.