OS Over Speed fault in delta drive

OS Over Speed fault in delta drive troubleshooting

Description

OS triggers when the actual motor speed (detected by encoder PG feedback) exceeds the Maximum Frequency setting by a certain margin (usually 10-15%). This is a safety fault to prevent the motor from flying apart.

Causes

1. Overhauling Load: A hoist or downhill conveyor accelerates the motor beyond the VFD's command.
2. PID Runaway: Poor PID tuning causes the drive to surge violently.
3. Encoder Noise: Electrical noise on the encoder lines is interpreted as high-frequency pulses (fake speed).

Solution

Control the speed:
1. Braking: Install a braking resistor to hold back overhauling loads.
2. Check Encoder: Verify shielding on encoder cables. Use an oscilloscope to check for noise.
3. Parameter: Increase the "Over Speed Detection Level" (Group 02 or 10) if the application requires slight overshoots.