Which mechanism leads to an OC4 at an ECS supply module, and why cannot be ensured that this error is always acknowledged?
Answer:
The error message OC4 is activated in the following states:
1. Brake resistance of low resistance
Mechanism: The UCE voltage is physically monitored. The monitoring is activated, when the brake resistance is of low resistance. The error can be reset with TRIP reset.
2. IGBT of low resistance
It is monitored, if the IGBT itself has become of low resistance. For this purpose the voltage at the brake resistance is applied. This error cannot be reset with TRIP reset, as in this case the device is damaged.
If no brake resistance is connected, the error mechanism occurs after '2.', as at the brake resistor no voltage can be measured. Therefore, the occurring OC4 error must be acknowledged by switching the 24 V DC.
