Relaying (DOT 1) Flashcards
1
Q
3
A
Interlocking Relay
2
Q
13
A
Synchronous Speed Device
3
Q
14
A
Under-speed Device
4
Q
20
A
Electrically Operated Valve
5
Q
21
A
Distance Relay
6
Q
26
A
Apparatus Thermal Device
7
Q
27
A
Under-voltage Relay
8
Q
33
A
Position Switch
9
Q
38
A
Bearing Protective Device
10
Q
40
A
Field Relay
11
Q
41
A
Field Circuit Breaker
12
Q
43
A
Manual Transfer/Selector Device
13
Q
46
A
Reverse Phase/Phase Balance Current Relay
14
Q
48
A
Incomplete Sequence Relay
15
Q
49
A
Machine/Transformer Thermal Relay
16
Q
50
A
Instantaneous Over-current Relay
17
Q
51
A
AC Time Over-current Relay
18
Q
52
A
AC Circuit Breaker
19
Q
55
A
Power Factor Relay
20
Q
56
A
Field Application Relay
21
Q
59
A
Over-voltage Relay
22
Q
62
A
Time Delay Stop/Start Relay
23
Q
63
A
Pressure Switch
24
Q
64
A
Ground Protective Relay
25
#70
Rheostat
26
#71
Level Switch
27
#72
DC Circuit Breaker
28
#80
Flow Switch
29
#81
Frequency Relay
30
#86
Lockout Relay
31
#87
Differential Protective Relay
32
#89
Line Switch
33
#90
Regulating Device
34
#94
Trip-free Relay
35
SOO PC 600.12 states what regarding relay action?
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
The Master Device List identifies relays based on?
or
What is three types of information found on a Master Device List?
1. Device ID
2. Setting history
3. Installation date
4. Manufacturer and model
37
Where can you find information regarding plant relays?
1. MNX Manuals
2. Master Device List
3. Plant Prints
38
What are the most common faults effecting power systems?
1. Three Phase
2. Line to line (two phase)
3. Single line to ground
39
What provides the first line of defense or protection against electrical or mechanic trouble?
"Primary" relaying
40
"Back-up" relaying occurs when?
Functions only when primary relaying fails.
41
Auxiliary relay (2 questions)?
- 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
Monitoring/verification relay?
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
Protective relay basic operating principles?
1. Electromagnetic attraction
2. Electromagnetic Induction
3. Thermal Induction
4. Electronic
44
Electromagnetic induction relays provide time-delayed operation. How is time-delayed adjusted?
By changing the distance the moving contact must travel.
45
Explain inverse-time curve characteristics?
One in which the operating time becomes less as the magnitude of the actuating quantity is increased (vise-versa).
46
Current-sensitive electromagnet?
Is wound with a few turns of heavy copper wire.
47
Voltage-sensitive electromagnet?
Is wound with many turns of fine copper wire.
48
What is a seal-in circuit and what is its function?
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
What is the most common method for detecting transmission line faults? Where is it measured?
– Detected by impedance measurement.
– Taken at the relay.
50
What is the cause of the most faults in a circuit?
Single phase to ground.
51
Why are pressure change relays more effective?
They provide a more sensitive protection than a voltage/current relay. Pressure sensing relays operate faster.
52
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?
– Prevents machine or system instability.
– Prevents overheating of the rotor.
53
What is used as a thermal device if not a relay?
CT is used as a thermal device…Increased current through the transformer causes increase in temperature.
54
What are four characteristics of a fault?
– Increase in current
– Reduced voltage
– Fault power always flows towards the fault
– Temperature rise on electrical equipment
55
What is a general philosophy for relay application?
Divide the power system into protective zones which can be adequately protected with the minimum amount of the system disconnected.
56
Where do relays receive their voltage and current from?
CT’s and PT‘s provide the relays the required energy for operation.
57
High speed relays operate at?
3 cycles or less.
58
Define “A” and “B” contacts?
- “A” open when relay is de-energized
| - “B” closed when relay is de-energized.
59
Explain the 51V. What makes it special compared to other 51 relays, and why.
Will a 51 V trip on starting amps?
– 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
What are considered the watchdogs of a system?
Protective relays
61
What is used to protect equipment from internal faults?
Differential relays.
62
What does RTD stand for, where are they located?
– Resistance temperature detectors.
| – Located in the critical temperature areas of a circuit/apparatus being protected.
63
How does 64 ground protective really operate?
If any part of the field becomes grounded, the circuit is complete and the relay will operate.
64
Microprocessors, list two pros and two cons?
Pros:
- tech-support
- multiple relays in one
Cons:
- reliability unknown
- complexity
65
Electromechanical. List two pros, two cons.
Pros:
- reliable
- not to sensitive
Cons:
- obsolete
- takes up space
66
Never_____________ across normally open contacts that are energized?
Test continuity/Ohm out
67
How is a sudden pressure fault actuated? Why are pressure relays more affective?
– Rapid gas pressure is caused by faults within the transformer.
– Pressure change relays provide a more sensitive protection… Operate faster than traditional relays
68
What devices are used to operate relays…used for protective relaying?
```
– Limit switch
– pressure switch
– flow switch
– level switch
– position switch
– RTD
– ultrasonic
```
69
Explain the operation of the 59N in (overvoltage relay)? Draw the circuit.
Current in the neutral transformer produces a voltage in the secondary which operates the relay if the voltage exceeds the predetermined level.
70
What is the purpose of a diode?
Prevents back feeding in the circuit.
71
What do you do if maintenance manual prints are different from plant prints?
Physically verify the circuit.
72
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?
– SOE
– Sequence of events
– Available through PSS/Wonderware and CSBIS Wonderware
73
Which directive outlines the maintenance and testing of protective relays?
MM-29
74
How do we design protective zones for power systems?
Overlapping to ensure defense in depth.
