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In-Class Sessions > Relaying (DOT 1) > Flashcards

Relaying (DOT 1) Flashcards

1
Q

3

A

Interlocking Relay

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2
Q

13

A

Synchronous Speed Device

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3
Q

14

A

Under-speed Device

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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

Under-voltage Relay

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8
Q

33

A

Position Switch

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9
Q

38

A

Bearing Protective Device

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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/Selector Device

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13
Q

46

A

Reverse Phase/Phase Balance Current Relay

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14
Q

48

A

Incomplete Sequence Relay

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15
Q

49

A

Machine/Transformer Thermal Relay

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16
Q

50

A

Instantaneous Over-current Relay

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17
Q

51

A

AC Time Over-current 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

56

A

Field Application Relay

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21
Q

59

A

Over-voltage Relay

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22
Q

62

A

Time Delay Stop/Start Relay

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23
Q

63

A

Pressure Switch

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24
Q

64

A

Ground Protective Relay

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25
Q

70

A

Rheostat

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26
Q

71

A

Level Switch

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27
Q

72

A

DC Circuit Breaker

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28
Q

80

A

Flow Switch

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29
Q

81

A

Frequency Relay

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30
Q

86

A

Lockout Relay

31
Q

87

A

Differential Protective Relay

32
Q

89

A

Line Switch

33
Q

90

A

Regulating Device

34
Q

94

A

Trip-free Relay

35
Q

SOO PC 600.12 states what regarding relay action?

A

PC 600.12 states that operators may not reset the below relay action until qualified person investigates cause:

  1. Differential Protective Relays (87)
  2. Ground Fault Relays (64)
  3. Sudden Pressure Relay (63)
36
Q

The Master Device List identifies relays based on?

or

What is three types of information found on a Master Device List?

A
  1. Device ID
  2. Setting history
  3. Installation date
  4. Manufacturer and model
37
Q

Where can you find information regarding plant relays?

A
  1. MNX Manuals
  2. Master Device List
  3. Plant Prints
38
Q

What are the most common faults effecting power systems?

A
  1. Three Phase
  2. Line to line (two phase)
  3. Single line to ground
39
Q

What provides the first line of defense or protection against electrical or mechanic trouble?

A

“Primary” relaying

40
Q

“Back-up” relaying occurs when?

A

Functions only when primary relaying fails.

41
Q

Auxiliary relay (2 questions)?

A
  • One that operates in response to the opening or closing of its operating circuit
  • Assist other relays or other devices in performance of a function (include timers, contact multiplier relays, lock-out relays, closing relays, and trip relays).
42
Q

Monitoring/verification relay?

A

Function is to verify power system conditions with prescribed limits and to initiate or permit automatic functions other than opening a circuit breaker during fault conditions.

43
Q

Protective relay basic operating principles?

A
  1. Electromagnetic attraction
  2. Electromagnetic Induction
  3. Thermal Induction
  4. Electronic
44
Q

Electromagnetic induction relays provide time-delayed operation. How is time-delayed adjusted?

A

By changing the distance the moving contact must travel.

45
Q

Explain inverse-time curve characteristics?

A

One in which the operating time becomes less as the magnitude of the actuating quantity is increased (vise-versa).

46
Q

Current-sensitive electromagnet?

A

Is wound with a few turns of heavy copper wire.

47
Q

Voltage-sensitive electromagnet?

A

Is wound with many turns of fine copper wire.

48
Q

What is a seal-in circuit and what is its function?

A
  1. A set of contacts that run parallel to the main circuit contacts, provides a low resistance parallel path that seals-in around the main contacts.
  2. It removes heavy trip current from spiral spring until the breaker trips.
49
Q

What is the most common method for detecting transmission line faults? Where is it measured?

A

– Detected by impedance measurement.

– Taken at the relay.

50
Q

What is the cause of the most faults in a circuit?

A

Single phase to ground.

51
Q

Why are pressure change relays more effective?

A

They provide a more sensitive protection than a voltage/current relay. Pressure sensing relays operate faster.

52
Q

Explain the purpose of a 40 device in loss of field protection, what do actions does it accomplish? AKA: why do generators have loss of field relays?

A

– Prevents machine or system instability.

– Prevents overheating of the rotor.

53
Q

What is used as a thermal device if not a relay?

A

CT is used as a thermal device…Increased current through the transformer causes increase in temperature.

54
Q

What are four characteristics of a fault?

A

– Increase in current
– Reduced voltage
– Fault power always flows towards the fault
– Temperature rise on electrical equipment

55
Q

What is a general philosophy for relay application?

A

Divide the power system into protective zones which can be adequately protected with the minimum amount of the system disconnected.

56
Q

Where do relays receive their voltage and current from?

A

CT’s and PT‘s provide the relays the required energy for operation.

57
Q

High speed relays operate at?

A

3 cycles or less.

58
Q

Define “A” and “B” contacts?

A
  • “A” open when relay is de-energized

- “B” closed when relay is de-energized.

59
Q

Explain the 51V. What makes it special compared to other 51 relays, and why.

Will a 51 V trip on starting amps?

A

– 51 V is an overcurrent relay with voltage restraint.

– Utilized in applications where inrush amps are high.

– 51 V protects the unit against overloads caused by faults and prevents a trip on starting amps.

60
Q

What are considered the watchdogs of a system?

A

Protective relays

61
Q

What is used to protect equipment from internal faults?

A

Differential relays.

62
Q

What does RTD stand for, where are they located?

A

– Resistance temperature detectors.

– Located in the critical temperature areas of a circuit/apparatus being protected.

63
Q

How does 64 ground protective really operate?

A

If any part of the field becomes grounded, the circuit is complete and the relay will operate.

64
Q

Microprocessors, list two pros and two cons?

A

Pros:

  • tech-support
  • multiple relays in one

Cons:

  • reliability unknown
  • complexity
65
Q

Electromechanical. List two pros, two cons.

A

Pros:

  • reliable
  • not to sensitive

Cons:

  • obsolete
  • takes up space
66
Q

Never_____________ across normally open contacts that are energized?

A

Test continuity/Ohm out

67
Q

How is a sudden pressure fault actuated? Why are pressure relays more affective?

A

– Rapid gas pressure is caused by faults within the transformer.

– Pressure change relays provide a more sensitive protection… Operate faster than traditional relays

68
Q

What devices are used to operate relays…used for protective relaying?

A 
– Limit switch
– pressure switch
– flow switch
– level switch
– position switch
– RTD
– ultrasonic
69
Q

Explain the operation of the 59N in (overvoltage relay)? Draw the circuit.

A

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

70
Q

What is the purpose of a diode?

A

Prevents back feeding in the circuit.

71
Q

What do you do if maintenance manual prints are different from plant prints?

A

Physically verify the circuit.

72
Q

What is the acronym used to identify a report that lists all the relay activities for the plant? What does The acronym stand for? Where can you access this information?

A

– SOE
– Sequence of events
– Available through PSS/Wonderware and CSBIS Wonderware

73
Q

Which directive outlines the maintenance and testing of protective relays?

74
Q

How do we design protective zones for power systems?

A

Overlapping to ensure defense in depth.

In-Class Sessions (31 decks)

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