Which of the following codes and device names are all right?
A. 49-Frequency Relay, 50-Instantaneous Overcurrent Relay, 67-Undervoltage Relay
B. 21-Distance Relay, 50-Instantaneous Overcurrent Relay, 51-Time Overcurrent Relay
C. 40-Loss of Excitation Relay, 59-Overvoltage Relay, 78-Differential Relay
D. 50-Time Overcurrent Relay, 51-Instantaneous Overcurrent Relay, 87-Differential Relay
Show Answer
Answer: B
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