Applicable Systems
VF-AS1
Symptoms
The VF-AS1 reports a braking transistor fault. The braking transistor circuit is abnormal, preventing proper regenerative energy dissipation.
Possible Causes
- Braking transistor short circuit failure
- Braking transistor gate drive circuit fault
- Braking resistor disconnected causing transistor to carry full load
Troubleshooting Steps
- Step 1: Check the braking transistor for short circuit
Transistor shows no short - Step 2: Verify the braking resistor is connected and within specification
Resistor is connected with correct value - Step 3: If the transistor is faulty, replace the drive unit
New unit has a functional brake transistor
How to Reset
To reset: Fix the brake transistor fault or replace the unit, then restart.
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Source: Toshiba VF-AS1 Inverter Manual, Toshiba Mitsubishi-Electric Industrial Systems
Category: PLC & VFD
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