PROTECTION

Card Set Information

Author:
KeGrant
ID:
274106
Filename:
PROTECTION
Updated:
2014-05-12 02:57:11
Tags:
PROTECTION
Folders:

Description:
PROTECTION
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user KeGrant on FreezingBlue Flashcards. What would you like to do?


  1. What is purpose of protection
    • To remove a fault before it takes down the entire system
    • It is able to detect the fault and clear it through fault clearing devices (CBs)
  2. What is difference between a protection system and a protection scheme
    • Protection System is each individual protective arrangement
    • Protection Scheme is the whole co-ordinated combination of each individual protection arrangement
  3. What is Selectivity(pertaining to protective relaying)
    Only a minimum portion of the power system should be disconnected to isolate a fault
  4. What is Security(pertaining to protective relaying)
    Schemes must be able to discrimminate between signals which require action, and those that do not
  5. What is Reliability(pertaining to protective relaying)
    Ability to operate without failure whenever a fault or abnormal condition exists
  6. What is Coordination(pertaining to protective relaying)
    Schemes must relate to each other so they operate in the right order
  7. What are 2 types of redundant protection?Why
    • Primary Protection and Standby Protection(backup)
    • -increased dependability
    • -one protection may be removed for maintenance and the equipment reamain protected
  8. What happens to current and voltage in a fault condition
    • Current will rise
    • Voltage will fall
  9. What are two reasons for utilizing instrument transformers
    • Provides useable quantities of voltage and current for:
    • metering and control
    • protective relays
  10. With respect to a CT, what is burden
    The amount of load connected to the secondary of the CT (ohmic value)
  11. How does exceeding burden impact a CT
    Could saturate the CT, no longer accurately reflect system current
  12. What is a Protection Zone
    • The section of power system that a particular protection covers
    • defined by the system they protect
    • boundaries determined by the location of CTs
  13. What is a Tripping Zone
    • The section of power system that is tripped by protection
    • boundaries determined by the CB locations
  14. What is overlap(pertaining to protection)
    Protection zones are typically 'overlapped' to prevent the possibility of unprotected areas
  15. What is breaker fail protection
    • A generator zone protection senses a generator fault and initiates protection operation. If the CB fails to open, 'Breaker Fail' protection operates to trip the adjacent zone
    • Breaker fail monitors for fault current flow through the CB that failed to open
  16. What are symmetrical components
    Used for analysis of 3 phase electrical power systems using vectors for the three phase quantities
  17. What is meant by Positive Sequence
    • Generators produce positive sequence voltage and current
    • Currents and voltages have a positive phase rotation
    • Each phase is equal in magnitude
    • Under balanced conditions only positive sequence exists
  18. What is meant by Negative Sequence
    • May exist in addition to positive sequence if conditions become unbalanced due to unbalanced loads or a fault
    • Unbalanced currents and voltages between phases result in Negative Sequence (negative phase rotation)
  19. What is meant by Zero Sequence
    • When conditions are unbalanced and there is a path to ground, positive, negative, and Zero Sequence quantities will exist
    • For zero sequence, phase quantities are equal in magnitude and in phase
  20. What is a RAS
    • Remedial Action Scheme
    • Automatic protection system designed to detect abnormal or predetermined system conditions, and take actions to maintain reliability
  21. What is purpose of RAS
    • Maintain angular stability
    • Control frequency
    • Prevent thermal overload
    • Voltage control
  22. What is the most typical RAS scheme
    • Generation Shedding(GenShed)
    • Immediately disconnects generator to reduce amount of power being transmitted on to the system following a transmission contingency
    • Maintains angular stability
  23. What are 4 key functions of SCADA
    • Telemetry: communication of data
    • Status Reporting: reports change of status of a device
    • Alarm Reporting: reports corresponding alarm points to control centre
    • Supervisory Control: allows remote operation of devices
  24. What are 3 major components of SCADA
    • Master Station: the control centre (FVO & SIO)
    • Remote Terminal Units(RTUs): the send/receive point at the station or equipment
    • Communication Facility: Microwave signals/towers, power line carriers, etc

What would you like to do?

Home > Flashcards > Print Preview