Principle of Relay

Remember: What is a relay?

• a. A switch that operates automatically
• b. A device that measures electrical quantities
• c. A device that transforms electrical energy into mechanical energy
• d. A device that stores electrical energy

Understand: Which one of the following is the correct function of a relay?

• a. To generate electrical signals
• b. To convert electrical energy into mechanical energy
• c. To detect faults in an electrical system
• d. To amplify electrical signals

Apply: An electrical system has a relay that operates when the current through a line exceeds a certain value. What type of relay is this?

• a. Overcurrent relay
• b. Differential relay
• c. Distance relay
• d. Directional relay

Analyze: A relay operates when the impedance of a line exceeds a certain value. Which type of relay is this?

• a. Overcurrent relay
• b. Differential relay
• c. Distance relay
• d. Directional relay

Evaluate: Which one of the following factors does not affect the operation of a relay?

• a. Temperature
• b. Frequency
• c. Voltage
• d. Time

Create: Design a protection scheme for a power system that includes a relay.

• a. Not applicable
• b. Not applicable
• c. Not applicable
• d. Not applicable