Relay Coordination Studies

RELAY COORDINATION STUDIES EXECUTIVE SUMMARY
Relay coordination studies – It is a well-known fact that the power system is not completely free from failures/faults. The key here is to mitigate the consequences during the event of faults. Damage to equipment during a fault can be reduced by quickly isolating the faulty portion from the rest of the health system. The objective of the protection coordination study is to determine optimum settings for protection devices such that the protection system isolates the minimum possible faulty portion at the earliest possible to ensure a reliable power supply for the health system. The optimum settings ensure required sensitivity and selectivity that protect workers from harm as well. The software used for the protection coordination study is ETAP, DigSilent Power factory, PSCAD, and PSS/E. The protection coordination study involves protection devices from various manufacturers such as Siemens, ABB/Hitachi, GE, Schneider, and so on.
WHY RELAY COORDINATION STUDY?
• To determine the optimum settings for protective devices in the system such as relays, releases, breakers, etc to ensure that proper coordination is achieved.
• To analyze time coordination curves (TCC) to verify the coordination between upstream and downstream protection devices including fuses.
• To check the sequence of operation of protection devices for various operating configurations.
• To find out the fault clearing time.
• To verify the protection coordination of t existing plant especially when there is a change in the network connectivity or source fault level.
• To generate calculations and finalize the unit protection settings of a generator, line, cable, transformer, motor, reactor, and capacitor banks.
• As an input for the calculation of incident energy in Arc Flash Studies.
HOW RELAY COORDINATION STUDY? (METHODOLOGY)
• Collection of inputs (SLD, equipment parameters – Voltage kV rating, Power MVA rating, Impedance, System fault level, X/R ratio, r