a) Consider a feeder as shown in Figure Q4(a) with earth fault relays RI and R2. Relay R1 is used for providing protecti

[answerhappygod]

A Consider A Feeder As Shown In Figure Q4 A With Earth Fault Relays Ri And R2 Relay R1 Is Used For Providing Protecti 1 (34.5 KiB) Viewed 34 times

a) Consider a feeder as shown in Figure Q4(a) with earth fault relays RI and R2. Relay R1 is used for providing protection against earth fault at the secondary side of 2.5 MVA, 11/3.3kV transformer, whereas, relay R2 has to provide protection at Bus B. Two CTs are used for protection. 200:5 CT is connected to instantaneous relay and 500:5 is connected to inverse current characteristic relay. Compute the setting of instantaneous and standard inverse units at relay at R1. Assume that maximum system unbalance is 20% and single line to ground fault current at Bus A is 480 A and at Bus B it is 650 A. Compute the time required by relay R2 to clear SLG fault at Bus B. (15 marks)