Device No. Description Device No.

Description
51_2 Negative Sequence Time Overcurrent 76 Dc Overcurrent Relay
52 Ac Circuit Breaker 77 Telemetering Device
53 Exciter or Dc Generator Relay 78 Phase Angle Measuring or Out-of-Step Protective Relay
54 Turning Gear Engaging Device 78V Loss of Mains
55 Power Factor Relay 79 Ac Reclosing Relay / Auto Reclose
56 Field Application Relay 80 Liquid or Gas Flow Relay
57 Short-Circuiting or Grounding Device 81 Frequency Relay
58 Rectification Failure Relay 81O Over Frequency
59 Overvoltage Relay 81R Rate-of-Change Frequency
59B Bank Phase Overvoltage 81U Under Frequency
59P Phase Overvoltage 82 Dc Reclosing Relay
59N Neutral Overvoltage 83 Automatic Selective Control or Transfer Relay
59NU Neutral Voltage Unbalance 84 Operating Mechanism
59P Phase Overvoltage 85 Carrier or Pilot-Wire Receiver Relay
59X Auxiliary Overvoltage 86 Locking-Out Relay
59_2 Negative Sequence Overvoltage 87 Differential Protective Relay
60 Voltage or Current Balance Relay 87B Bus Differential
60N Neutral Current Unbalance 87G Generator Differential
60P Phase Current Unbalance 87GT Generator/Transformer Differential
61 Density Switch or Sensor 87LG Ground Line Current Differential
62 Time-Delay Stopping or Opening Relay 87S Stator Differential
63 Pressure Switch Detector 87S Percent Differential
64 Ground Protective Relay 87L Segregated Line Current Differential
64F Field Ground Protection 87M Motor Differential
64S Sub-harmonic Stator Ground Protection 87O Overall Differential
64TN 100% Stator Ground 87PC Phase Comparison
65 Governor 87RGF Restricted Ground Fault
66 Notching or Jogging Device/Maximum Starting Rate/Starts 87T Transformer Differential
Per Hour/Time Between Starts 87V Voltage Differential
67 Ac Directional Overcurrent Relay 88 Auxiliary Motor or Motor Generator
67G Ground Directional Overcurrent 89 Line Switch
67N Neutral Directional Overcurrent 90 Regulating Device
67P Phase Directional Overcurrent 91 Voltage Directional Relay
67SG Sensitive Ground Directional Overcurrent 92 Voltage And Power Directional Relay
67_2 Negative Sequence Directional Overcurrent 93 Field-Changing Contactor
68 Blocking Relay / Power Swing Blocking 94 Tripping or Trip-Free Relay
69 Permissive Control Device 50/74 Ct Supervision
70 Rheostat 27/50 Accidental Generator Energization
71 Liquid Switch 27TN/59N 100% Stator Earth Fault
72 Dc Circuit Breaker
73 Load-Resistor Contactor
74 Alarm Relay
75 Position Changing Mechanism

GEDigitalEnergy.com 3