Braking Transistor Overload Fault

What does boL mean?

The internal braking transistor is experiencing an overload, typically due to a high regeneration power or an excessive repetition frequency during braking cycles. This can also trigger if the transistor's protective function is enabled incorrectly while a regenerative converter is present, or if the transistor itself is faulty. Prolonged overload can lead to component damage and potential drive failure.

• Braking resistor resistance value is too high, preventing sufficient current flow to dissipate regenerated energy.
• Braking resistor wiring is loose or disconnected at drive terminals DB and B2 (or equivalent).
• Excessive regeneration energy from a high inertia load combined with short deceleration times (e.g., C1-02).
• Deceleration time (C1-02, C1-03) set too short for the kinetic energy of the load.
• Faulty internal braking transistor within the drive's power section.

Click steps to track your progress.

1. 1

   Measure the resistance of the external braking resistor with an ohmmeter and compare to its specified value.

2. 2

   Verify all braking resistor wiring connections at drive terminals DB and B2 are secure and continuous.

3. 3

   Increase the deceleration time settings (C1-02, C1-03) to reduce the peak regenerative power.

4. 4

   Check the braking resistor for physical damage, signs of overheating (discoloration), or open circuit.

5. 5

   Monitor parameter U1-06 (DC Bus Voltage) during deceleration to observe regeneration voltage levels.