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1
- Master element: normally used for hand-operated devices. A common use is the spring-return-to-center control switch for circuit
- breakers, where the switch contacts are lOlT (trip), lOlc (close), lOlSC (closed when turned to close and remains closed when released, opens when turned to trip and remains open when
- released). When several breakers are involved, they are identified by 101, 201, 301, and so on.
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2
Time-delay starting or closing relay: except device functions 48, 62, and 79
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3
Checking or interlocking relay
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6
Starting circuit breaker
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8
Control power-disconnecting device
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13
Synchronous-speed device
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15
Speed- or frequency-matching device
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16
Data Communications Device
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17
Shunting or discharge switch
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18
Accelerating or decelerating device
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19
Starting-to-running transition contactor
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20
Electrically operated valve
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22
Equalizer circuit breaker
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23
Temperature control device
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25
Synchronizing or synchronism-check device
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26
Apparatus thermal device
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31
Separate excitation device
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32
Directional power relay
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34
Master sequence device
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35
Brush-Operating or Slip-Ring Short-Circuiting Device
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36
Polarity or polarizing voltage device
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37
Undercurrent or underpower relay .
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38
Bearing protective device
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39
Mechanical conduction monitor
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42
Running circuit breaker
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43
Manual transfer or selector device
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44
Unitlsequence starting relay
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45
Atmospheric condition monitor
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46
Reverse-phase or phase-balance relay
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47
Phase-sequence voltage relay
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48
Incomplete-sequence relay
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49
Machine or transformer thermal relay
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50
Instantaneous overcurrent
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51
ac time overcurrent relay
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52
- ac circuit breaker: mechanism-operated contacts are:
- a. 52a, 52aa: open when breaker cantacts are open, closed when breaker contacts are closed
- b. 52b, 52bb: closed when breaker contacts are open, open when breaker contacts are closed
- 52aa and S2bb operate just as mechanism moiion starts; known as high-speed contacts
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53
Exciter or dc generator relay
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54
Turning Gear Engaging Device
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56
Field application relay
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57
Short-circuiting or grounding device
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58
Rectification failure relay
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60
Voltage or current balance relay
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61
Density Switch or Sensor
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62
Time-delay stopping or opening relay
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66
Notching or jogging device
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67
Ac directional overcurrent relay
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69
Permissive control device
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73
Load-resistor contactor
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75
Position Changing Mechanism
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78
Phase-angle measuring or out-of-step protective relay
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83
Automatic selective control or transfer relay
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85
Carrier or pilot-wire receiver relay
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87
Differential protective relay
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88
Auxiliary motor or motor generator
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91
Voltage directional relay
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92
Voltage and power directional relay
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93
Field-changing contactor
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94
Tripping or trip-free relay
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