DIFFERENTIAL RELAY

What is the basic function of a differential relay?

• A. To detect the fault in the system
• B. To monitor the voltage levels in the system
• C. To monitor the current flowing through the system
• D. To regulate the frequency of the system

Why is a differential relay used in power system protection?

• A. To protect against overvoltage conditions
• B. To protect against overcurrent conditions
• C. To protect against earth fault conditions
• D. To protect against internal fault conditions

Which of the following is a typical application of differential relays?

• A. Protection of transmission lines
• B. Protection of generators
• C. Protection of motors
• D. Protection of transformers

A differential relay can detect which type of fault in a power system?

• A. External faults
• B. Internal faults
• C. Overvoltage faults
• D. Underfrequency faults

Which of the following is an advantage of using a differential relay over other types of relays?

• A. Provides faster tripping times
• B. Requires less maintenance
• C. Has a lower cost
• D. Is less susceptible to false trips

Design a differential relay scheme for protecting a transformer with a rating of 50 MVA, 132 kV/11 kV, with a ratio of 2:1, against internal faults. What are the CT ratios required for the scheme?

• A. 2000/5 A for primary and secondary CTs
• B. 500/1 A for primary and secondary CTs
• C. 400/1 A for primary and secondary CTs
• D. 800/1 A for primary and secondary CTs