TRANSIENT OPERATION OF RELAYS AND PROTECTION CIRCUITS

Abstract

The development of static relays is nearly 30 years old but still to develop a suitable static relay is a problem. The maloperation of relays under d.c. offset transient conditions and reliability are the two main preventive factors for their actual use. The presence of non-linearity in cores of C.Ts. and P.Ts etc. too give rise to transients. The use of various network to minimise the C.T. saturation or various special device of C.T. has lead towards satisfactory reproduction of primary signals into secondary side. The d.c. transient suppression or cancellation has also given improved performance. Finally, the development of suitable comparator, which is immune for the presence of d.c. transients in the input signals, gave a promising nature for the development of the relay. In this thesis, transient behaviour of various components used in the relays is discussed. The methods have also been suggested to minimise the d.c. transients. The behaviour of comparator under transient conditions has also been paid attention. Finally, the suitable comparator has been developed which will give improved performance.