Fault-development control in a.c.-d.c. convertors

A new principle of protection against convertor faults is proposed, consisting of a direct control of the valve-firing sequence. Upon detection of the faulty condition, the firing/blocking sequence most suitable for the development of the particular type of fault is applied. The results of this investigation show that, to a greater or lesser extent, all types of convertor faults benefit from the use of fault-development control in terms of quicker recoveries and fault-current levels.