In this topic, you study Protection Zone in Power System.
The protective relaying of a power system is planned along with system design. The circuit breakers are located at appropriate points.
Depending upon the rating of the machine, its location, importance, probability of faults and abnormal conditions etc. each power system component of transmission line e.g. bus bar, cables, capacitors, loads etc. is covered by protective zone.
A part of the system protected by a certain protective scheme is called as protective zone or zone of protection.
Selectivity to the system is an important one. For this the whole system is divided into different protective zones.
- Generator protected zone.
- Generator Transformer unit protection zone.
- Bus-bar Protection zone.
- Transmission Line Protection zone.
The entire part of a power system is covered by several protective zones and no part of the system is left unprotected. A protective zone is shown in Fig. 1.
Suppose a fault occurs in a specific zone, then the circuit breaker within that zone only will operate and that particular faulty section is isolated but the other healthy sections will be unaffected. Different protective zones are shown in Fig. 1.
Fig. 1: Different Protective Zones