SV0454 Illegal Rotor Position Detection fault in Fanuc drive

SV0454 Illegal Rotor Position Detection fault in Fanuc drive

Description

SV0454 is a specific alarm for Permanent Magnet (Synchronous) AC motors. Unlike induction motors, PM motors require the drive to know the exact physical orientation of the rotor magnets relative to the stator coils *before* applying current. This is called "Pole Detection." If the drive cannot determine the rotor position upon startup, or if the position data fluctuates wildly during the initial magnetic scan, SV0454 is generated.

Cause

• Loose Sensor: The pulse coder on the back of the motor is loose. If the motor shaft turns but the encoder doesn't move perfectly with it, pole detection fails.
• Wrong Motor Code: The parameter for "Motor Type" is incorrect. The drive is trying to detect poles for a 4-pole motor, but it's connected to an 8-pole motor.
• Cable Noise: Electrical noise on the feedback cable during the startup phase corrupts the Hall signal or serial data.

Solution

1. Check Coupling: Remove the red cap on the motor. Check the coupling between the motor shaft and the encoder. It must be absolutely rigid.
2. Verify Parameters: Ensure the Motor ID in parameter 2020 matches the nameplate exactly.
3. Encoder Replacement: If the mechanics are tight, the magnetic sensors inside the pulse coder used for commutation are likely damaged.