Electrical Sciences System Components

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Author:
ereim
ID:
30183
Filename:
Electrical Sciences System Components
Updated:
2010-08-17 13:26:07
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System Components
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Description:
System Components
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  1. The current in amperes that a conductor can carry continuously under the conditions of use without exceeding its temperature rating
    Ampacity
  2. The permanent joining of metallic parts or circuits assuring electrical continuity and capacity to safely conduct any current likely to be imposed
    Bond
  3. Device used to completely disconnect a circuit when any abnormal condition exists.
    Circuit breaker
  4. Any wire, cable, or substance capable of carrying an electrical current
    Conductor
  5. A device that protects a circuit from an overcurrent condition only. It has a fusible link directly heated and destroyed by the current passing through it
    Fuse
  6. A conducting connection, whether intentional or accidental, between a circuit and piece of equipment, the earth, or some body serving as earth; a place of zero electrical potential
    Ground
  7. The voltage between any given conductor and any point at ground potential
    Ground voltage
  8. Voltage above 15,000 volts
    High voltage
  9. Voltage between 15,000 and 600 volts
    Intermediate voltage
  10. A current-carrying conductor intended to deliver power to or from a load normally at an electrical potential other than ground
    Leg
  11. 600 volts or less
    Low voltage
  12. Suited for circuits rated at 600 volts or lower
    Low voltage circuit breaker
  13. Control device used to de-energize the motor in a low voltage condition and keep it from re-starting automatically upon return of normal voltage
    LVP controller
  14. Control device used to de-energize the motor in a low voltage condition and restart the motor when normal voltage is restored
    LVR controller
  15. Control device maintains the motor across the line at all times
    LVRE controller
  16. Provides control and protect for the operation of a motor
    Motor controller
  17. A current-carrying conductor normally tied to ground so that the electrical potential is zero
    Neutral
  18. The greatest root mean square (effective) difference of potential between any two legs of the circuit
    Phase voltage
  19. Designed to cause the prompt removal of any part of a power system that might cause damage or interfere with the effective and continuous operation of the rest of the system
    Protective relays
  20. Any failure that may occur within a given zone will cause the tripping or opening of all circuit breakers within that zone
    Zone of protection
  21. Explain the following terms as they apply to Electrical Distribution Systems

    1. Single-line (one-line) diagram

    2. Commercial or utility power

    3. Diesel power

    4. Failure-free power

    5. Neutral grounding

    6. Voltage class

    7. Protective relays

    8. Overlapping protective zones

    Single-line diagram - simple and easy-to-read diagram showing power supplies, loads, and major components in the distribution system.

    Commercial or utility power - electric power supplied to the facility

    Diesel power - economical/practical source of standby power

    Failure-free power - power supplied to vital equipment with automatic switching so that interruption of power is minimized

    Neutral grounding - helps prevent accidents to personnel and damage to property by fire

    Voltage class - high voltage > 15,000 volts, intermediate voltage is 600-15,000 volts, low voltage # 600 volts

    Protective relays - cause prompt removal of any part of a power system that suffers a short circuit

    Overlapping protective zones - created around each element of the power system to prevent element failure from interrupting the whole system operation
  22. Describe the protection provided by each of the following

    1. Breakers

    2. Fuses

    3. Protective relays

    • Breakers - disconnect component from the power system
    • Fuse - protects component from overcurrent
    • Protective relays - cause prompt removal of any part of a power system that suffers a short circuit
  23. State the purpose of circuit breakers
    The purpose of a circuit breaker is to provide a means for connecting and disconnecting circuits of relatively high capacities without causing damage to them.
  24. Given a simple schematic of a circuit breaker control circuit, describe the operation of that breaker during remote operation and automatic tripping
    • The three most commonly used automatic trip features for a circuit breaker are overcurrent, underfrequency, and undervoltage.
    • If any one of the conditions exists while the circuit breaker is closed, it will close its associated contact and energize the tripping coil, which, in turn, will trip the circuit breaker.
  25. List the three most widely used protective features that may be incorporated into a circuit-breaker control circuit
    The three most commonly used automatic trip features for a circuit breaker are overcurrent, underfrequency, and undervoltage
  26. State the function of motor controllers
    Motor controller - controls and protects the operation of a motor
  27. State three protective features (overloads) that may be incorporated into a motor controller
    Controller’s protective features - fuses, thermal overloads, and magnetic overloads
  28. Given a simplified drawing of a motor controller, describe the operation of that motor controller
    • 4-Wire Three Phase Wye System Neutral connected Node.
    • Safest Possible Multi-purpose distribution system

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