Correct Answer - Option 1 : Sensitivity
Protective system:
A protection system is designed for the continuous operation of the power system and it should ensure maximum continuity of service with minimum damage to life, equipment, and property.
Objectives of system protection:
Speed of operation: Protection system should ensure minimum fault duration and consequently no equipment damage. If fault clearing is delayed then the system equipment will damage due to severe thermal and mechanical stress. so the protection system should detect the fault and clear the fault as quickly as possible.
Sensitivity: Protective relay should able to detect even the smallest possible value of fault current in the protection zone. 1.2 Ifl < Ipick up < Ifmin . It can be achieved with a proper setting to the protective system. Under this objective, the Relay system is designed to operate under a predetermined condition
Selectivity: The protection system should ensure max continuity of service with minimum system interruption. The protective relay should able to discriminate whether the fault is inside the zone or outside the zone of protection.
Reliability: It is the assurance that the protection system will operate 100% correctly. It has two aspects
- Dependability: It should operate whenever it is required.
- Security: It should not operate whenever it is not required.
Simplicity: The relaying system should have a minimum number of components and associated circuitry to achieve protection objectives.
Economical: A protection system should provide maximum protection at a minimum cost.
Relay: The relay is a switch that controls the circuits electromechanically. The main operation of this device is to make or break contact with the help of a signal without any human involvement. It is mainly used to control a high powered circuit using a low power signal.
