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Protective Relaying > Protective Relaying > Flashcards

Protective Relaying Flashcards

1
Q

3

A

Interlocking relay

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2
Q

12

A

Over-speed

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3
Q

14

A

Under-speed

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4
Q

20

A

Electrically operated valve

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5
Q

21

A

Distance relay

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6
Q

26

A

Apparatus thermal device

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7
Q

27

A

Undervoltage relay

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8
Q

33

A

Position switch

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9
Q

38

A

Bearing protective

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10
Q

40

A

Field Relay

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11
Q

41

A

Field circuit breaker

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12
Q

43

A

Manual transfer or selector device

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13
Q

46

A

Reverse-phase, or phase-balance, current relay

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14
Q

48

A

Incomplete sequence relay

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15
Q

49

A

machine, or transformer thermal relay

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16
Q

50

A

Instantaneous overcurrent relay

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17
Q

51

A

AC time overcurrent relay

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18
Q

52

A

AC circuit breaker

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19
Q

55

A

Power factor relay

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20
Q

59

A

Overvoltage relay

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21
Q

63

A

Pressure switch

22
Q

64

A

Ground protective relay

23
Q

70

A

Rheostat

24
Q

72

A

DC circuit breaker

25
Q

80

A

Flow switch

26
Q

81

A

Frequency Relay

27
Q

86

A

Locking-out relay

28
Q

87

A

Differential protective relay

29
Q

94

A

trip-free relay

30
Q

Protective relays have been described as the _____ of the system

A

Watchdogs

31
Q

Auxiliary relay

A

operates in response to the opening or closing of its circuit to assist another relay or device

32
Q

Verification relay

A

verify power system conditions and permit automatic functions other than opening a circuit breaker during fault conditions.

33
Q

The most common fault characteristics

A
  1. increased current in one or more phases flowing towards the fault (2 to 20 times normal load current)
  2. reduced voltage in one or more phases ( voltage will be lowest at the fault)
  3. Fault power always flows toward the fault
  4. Temp rise in electrical equipment.
34
Q

Relays operate on two fundamentally different operating principles

A
  1. electromagnetic attraction

2. electromagnetic induction

35
Q

A contact that is open when the relay is de-energized is termed an open or ___ contact and a contact that is closed when the relay is de-energized is termed a closed or a ___ contact

A

a

b

36
Q

High speed relays operate in ____ cycles or less while slow speed relays operating time _____

A

3

exceed 3 cycles

37
Q

Differential relays protect against ____

A

internal faults

38
Q

59n (ground fault overvoltage relay)

A

current in the neutral transformer produces a voltage in the secondary which operates the relay if the voltage exceeds a predetermined level

39
Q

For pumping units where inrush amps are high, what is it desirable to provide

A

a relay (51v) which will properly protect the unit against overloads caused by a fault while preventing a trip on starting amps

40
Q

What are four major faults effect power systems

A
  1. Three phase
  2. Line to line ( two phase) or Phase to phase
  3. double line to ground
  4. single line to ground (phase to ground)
41
Q

____ relaying is the first line of defense or protection against electrical or mechanical trouble

A

Primary

42
Q

_______ relaying functions only when primary relaying fails

A

“back-up”

43
Q

relays that empoly the electromagnetic induction principle provide a ______, which can be adjusted on some, by changing the distance the moving contact must travel

A

time - delayed operation

44
Q

What are a RTD and where are they located?

A

Resistance Temperature Detectors

located in the critical temp areas of the apparatus being protected to provide either an alarm or a direct trip action.

45
Q

what is ICS

A

indicating contactor switch

46
Q

sealed in

A

prevents arcing
shunt in parallel with the relays main contacts
keeps contacts closed until reset

47
Q

An inverse-time curve is

A

the operating time becomes less as the magnitude of the actuating quantiy is increased

48
Q

what is the most common fault

A

phase to ground

49
Q

time delay is obtained by

A

adjusting the travel distance of the contacts

50
Q

distance relays use what to detect faults

A

impedance

Protective Relaying (1 decks)

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