Unblocking can only be done manually. To enable the converter, the user must:
- Set the current reference to zero;
- Initiate the enabling order. Regular pulses will be sent to the thyristors (instead of pulses from bypass thyristors).
- Set the current or voltage reference to the desired value. After unblocking, the converter will adjust to this given value with a certain delay depending on the limits imposed by the rate of change limiters. To maintain the current margin, the current ramp on the rectifier cannot be slower than that of the inverter at start-up.