ELECTRICAL DISTRIBUTION EXAM

1. A single, or one-line diagram of a distribution system is a simple and easy-to-read diagram showing power supplies, loads, and major components in the distribution system.

2. Diesel power is power generated by a diesel-driven generator. Diesel-driven generators are the most economical and practical source of “standby power.”

3. Failure-free power is accomplished by providing vital equipment with automatic switching between two or more power supplies so that interruption of power is minimized.

4. Voltage in distribution systems is classified into three groups: high voltage, intermediate voltage, and low voltage. High voltage is voltage that is above 15,000 volts, intermediate voltage is voltage between 15,000 volts and 600 volts, and low voltage is voltage at 600 volts or less.

5. Protective relays can be used for short circuit or overcurrent protection only.

6. A separate zone of protection is provided around each system element in a distribution system.

7. The purpose of a circuit breaker is to break the circuit and stop the current flow when the current exceeds a predetermined value regardless of damage to the circuit or the circuit breaker.

8. A low-voltage circuit breaker is one which is suited for circuits rated                    volts or lower.

9. High-voltage circuit breakers (including breakers rated at intermediate voltage) are used for service on circuits with voltage ratings higher than                   volts.

10. One of the most commonly used low-voltage air circuit breakers is the molded case circuit breaker.

11. In the early stages of electrical system development, the major portion of high-voltage circuit breakers were oil circuit breakers.

12. Air-blast circuit breakers have recently been developed for use in extra high-voltage applications with standard ratings up to 765,000 volts.

13. The basic functions of a motor controller are to control and protect the operation of a motor.

14. Manual controllers provide low voltage protection or low voltage release.

15. A large percentage of controller applications require that the controller be operated from a remote location or operate automatically in response to control signals.

16. Phase voltage is the greatest root mean square (effective) difference of potential between any two legs of the circuit.

17. The Wye system has the same voltage characteristics as the Delta system.

18. The simplest three-phase system is the 3-wire Delta configuration, normally used for transmission of power in the intermediate voltage class from approximately 15,000 volts to 600 volts.

19. Each phase of the 3f distribution system is a single-phase generator electrically spaced 120 degrees from the other two phases.

20. The full load ampacity of the neutral conductor in a Wye system,must be sized to               times the highest phase ampacity.