Power framework comprising of generators, transformers, transmission and appropriation lines etc. So at some point or another, some failure can happen on any piece of the framework. At the point when any fault happens on any piece of the framework, it must be recognized and the undesirable piece of the framework must be detached from the solid circuit.
The primary function of the protective relay is to identify the fault and expel it from the circuit yet there are couple of essential factors which ought to be kept in thought while choosing a hand-off for securing a power system.
Selectivity: It is the capacity of a protective relay to choose effectively that piece of the system which is in a bad position and disengage the unfortunate piece of the system from whatever is left of the framework.
Speed: This is another element of a protective transfer which indicates how much time the relay takes to work. The relay must rush to work on the grounds that the huge current can harm the whole solid circuit in a matter of seconds.
Affectability: It is the capacity of a protective relay to work with a low benefit of inciting amount. An affectability of a relay is a component of the volt-amperes contribution to the transfer loop important to its task.
Dependability: Another critical part of a protective relay which additionally matters a great deal is its consistent quality. It is the capacity of the transfer to work under the predetermined conditions. The protective relay should extremely solid to work just in the irregular conditions.
Effortlessness: The relay system must be extremely straightforward in the circuit so it can be effectively kept up. The less difficult the security plot the more noteworthy will be its dependability too.
Economy: The most imperative factor in all things is the economic perspective. At times the perfect protection conspire goes to extremely costly cut-off points. According to rule, the protective gear ought not to be over 5% of the aggregate cost.