489

Question 1

R2

Answer 1

Phase distance backup zone 2 (21 - impedance relay)
Negative sequence (46 - reverse phase, phase balance current, or power rectifier misfire relay)
Inadvertent energization (50/27 - short circuit selective relay or device/ac under voltage)

5P

Question 2

R3

Answer 2

Neutral over current (50/51N - short circuit selective relay or device/ac over current relay)
Phase differential (87 - differential current relay)

87G1X

Question 3

R4

Answer 3

Breaker failure (50BF - short circuit selective relay)

87T1X

Question 4

R5

Answer 4

Relay operation alarm

Annunciator

Question 5

R6

Answer 5

95U trouble

Annunciator

Question 6

R1

Answer 6

Phase distance backup zone 1 (21 - impedance relay)
Over excitation (24 - bus tie circuit breaker contractor or switch?)
Loss of field (40 - field relay)
Ground over current (50/51N - short circuit selective relay or device/ac over current relay)
Three phase over voltage (59 - ac over voltage)
Phase differential (87 - differential current relay)

5C