Protective Relaying : Introduction

Protective Relaying (Part1)     
       Protective relaying is one of the several features of the power system design. Every part of the power system is protected. The factors affecting the choice of protection are type and rating of equipment, location of the equipment, types of faults, abnormal conditions and cost.
       The protective relaying is used to give an alarm or to cause prompt removal of any element of power system from service when that element behaves abnormally. The abnormal behaviour of an element might cause damage or interference within effective operation of rest of the system. The protective relaying minimises the damage to the equipment and interruption to the service when electrical failure occurs. Along with some other equipments the relays help to minimise damage and improve the service.
       The relays are compact and self contained devices which can sense the abnormal conditions. Whenever abnormal condition exists, the relay contact get closed. This inturn closes the trip circuit of a circuit breaker. The circuit breakers are capable of disconnecting a fault element, when they are called upon to do so by the relays. Thus entire process includes the operations like occurrence of fault, operation of relay, opening of a circuit breaker and removal of faulty element. This entire process is automatic and fast, which is possible due to effective protective relaying scheme.
       The protective relaying scheme includes protective current transformers, voltage transformers, protective relays, auxiliary relays, secondary circuits, trip circuits etc. Each component plays its own role, which is very important in the overall operation of the scheme. The protective relaying is the team work of all these components. The protective relaying also provides the indication of location and type of the fault.

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1 comment:

  1. The protective relays are the electromagnetic devices, which rely on coils operating on the moving parts. They help in detecting any abnormal operating conditions, including, over voltage, over frequency, over current, under frequency and reverse flow of power.The Protective Relays manufacturers design these components to trip the circuit breaker on detecting a fault.