Applicable Systems
VF-AS1
Symptoms
The VF-AS1 reports a DC bus undervoltage fault. The bus capacitor voltage dropped below the minimum operating level.
Possible Causes
- Input power supply voltage dip or momentary outage
- Power supply capacity insufficient for the drive load
- Rectifier bridge fault reducing DC bus charging
Troubleshooting Steps
- Step 1: Measure the input supply voltage during operation
Voltage remains stable within the rated range - Step 2: Check the rectifier bridge for diode failure
Rectifier bridge is healthy - Step 3: Install a voltage stabilizer if supply dips are frequent
Supply voltage is stable
How to Reset
To reset: Restore the DC bus voltage to the rated level, then reset.
Source: Toshiba VF-AS1 Inverter Manual, Toshiba Mitsubishi-Electric Industrial Systems
Category: PLC & VFD