Braking Transistor Overload Fault

What does boL mean?

The braking transistor, an internal component responsible for dissipating regenerative energy, is experiencing an overload condition. This occurs when the drive's deceleration duty cycle or regenerative power is too high, or if the transistor itself is faulty. Persistent overload can lead to overheating and irreversible damage to the transistor, impairing the drive's ability to manage braking energy safely and effectively.

• Braking transistor is overheating or overloaded (P4-04).
• Excessive braking current drawn.
• Braking resistor failure or short circuit.
• Drive attempting to brake a load that is too heavy.

Click steps to track your progress.

1. 1

   Increase the deceleration time parameter in the drive settings to reduce the rate of regenerative energy generation.

2. 2

   If an external regenerative converter is used, verify that the internal braking transistor protection is disabled (parameter L8-55 set to 0).

3. 3

   Evaluate the mechanical system for any excessive inertia or frequent braking demands that might require an external braking resistor or regenerative converter.

4. 4

   If the fault persists after adjusting parameters and external components, the internal braking transistor may be damaged, requiring drive replacement.