Abbreviation:
ANSI stands for American National Standards Institute
What is ANSI?
In the design of electrical power systems, the ANSI standard device numbers show the parts of a protective device like a relay or circuit breaker. These kinds of devices protect electrical systems and parts from damage, when something unexpected happens like an electrical fault.
One physical device may correspond to one function number, like “29 Isolating Contactor,” or a single physical device may have many function numbers associated with it, like a numerical protective relay. Letters can be added to the end or beginning of the name of a device to give more information about its purpose and function.
An electrical power system is designed using the ANSI standard device numbers (as per ANSI/IEEE standard C37.2). If there is an issue with the electrical grid, these devices will prevent damage. Below is a list of ANSI device numbers and their corresponding abbreviations:
| SL. NO | ANSI STANDARD ABBREVIATION | ANSI STANDARD DEVICE NUMBER |
|---|---|---|
| 1 | Master Element | 1 |
| 2 | Time-delay Starting / Closing relay | 2 |
| 3 | Checking / Interlocking Relay | 3 |
| 4 | Master Protection | 4 |
| 5 | Stopping Device / Emergency Stop Switch | 5 |
| 6 | Starting Circuit Breaker | 6 |
| 7 | Rate of Change Relay | 7 |
| 8 | Control Power Disconnecting Device | 8 |
| 9 | Reversing Device | 9 |
| 10 | Unit Sequence Switch | 10 |
| 11 | Multifunction Device | 11 |
| 12 | Overspeed Device | 12 |
| 13 | Synchronous Speed Device | 13 |
| 14 | Under-speed Device | 14 |
| 15 | Speed / Frequency Matching Device | 15 |
| 16 | Data Communications Device | 16 |
| 17 | Shunting / Discharge Switch | 17 |
| 18 | Accelerating / Deaccelerating Device | 18 |
| 19 | Starting to Running Transition Contactor | 19 |
| 20 | Electrically-Operated Valve (Solenoid Valve) | 20 |
| 21 | Distance-Relay | 21 |
| 22 | Ground-Distance | 21G |
| 23 | Phase-Distance | 21P |
| 24 | Equalizer Circuit Breaker | 22 |
| 25 | Temperature control device or Heater | 23 |
| 26 | Volts per (hertz) relay | 24 |
| 27 | Synchronizing / synchronism-check device | 25 |
| 28 | Apparatus thermal device or Temperature Switch | 26 |
| 29 | Undervoltage Relay | 27 |
| 30 | Phase Undervoltage | 27P |
| 31 | DC undervoltage Relay | 27S |
| 32 | Third Harmonic Neutral Undervoltage | 27TN |
| 33 | 100% (Stator) Earth Fault | 27TN/59N |
| 34 | Auxiliary Under-voltage | 27X |
| 35 | Under-voltage Auxiliary Input | 27 AUX |
| 36 | Bus/Line Under-voltage | 27/27X |
| 37 | Accidental Generator Energization | 27/50 |
| 38 | Flame Detector | 28 |
| 39 | Isolating Contactor | 29 |
| 40 | Annunciator Relay | 30 |
| 41 | Separate Excitation Device | 31 |
| 42 | Directional Power Relay | 32 |
| 43 | Low Forward Power | 32L |
| 44 | High Directional Power | 32H |
| 45 | Watt-metric Zero-Sequence Directional | 32N |
| 46 | Directional Power | 32P |
| 47 | Reverse Power | 32R |
| 48 | Position Switch | 33 |
| 49 | Master Sequence Device | 34 |
| 50 | Brush-Operating / Slip-ring Short Circuiting Device | 35 |
| 51 | Polarity / Polarizing Voltage Device | 36 |
| 52 | Undercurrent / Underpower Relay | 37 |
| 53 | Under-power | 37P |
| 54 | Bearing Protective Device / Bearing Rtd | 38 |
| 55 | Mechanical Condition Monitor (Vibration) | 39 |
| 56 | Field Relay / Loss of Excitation | 40 |
| 57 | Field Circuit Breaker | 41 |
| 58 | Running Circuit Breaker | 42 |
| 59 | Manual Transfer / Selector Device | 43 |
| 60 | Unit Sequence Starting Relay | 44 |
| 61 | Fire Detector | 45 |
| 62 | Reverse-Phase (or) Phase Balance Current Relay (or) Stator Current Unbalance | 46 |
| 63 | Phase-Sequence (or) Phase Balance Voltage Relay | 47 |
| 64 | Incomplete Sequence Relay / Blocked Rotor | 48 |
| 65 | Machine or Transformer Thermal Relay / Thermal Overload | 49 |
| 66 | RTD Biased Thermal Overload | 49RTD |
| 67 | Instantaneous Overcurrent Relay | 50 |
| 68 | Breaker Failure | 50BF |
| 69 | Current Disturbance Detector | 50DD |
| 70 | End Fault Protection | 50EF |
| 71 | Ground Instantaneous Overcurrent | 50G |
| 72 | Isolated Ground Instantaneous Overcurrent | 50IG |
| 73 | Acceleration Time | 50LR |
| 74 | Neutral Instantaneous Overcurrent | 50N |
| 75 | Neutral Instantaneous Breaker Failure | 50NBF |
| 76 | Phase Instantaneous Overcurrent | 50P |
| 77 | Sensitive Ground Instantaneous Overcurrent | 50SG |
| 78 | Split -Phase Instantaneous Current | 50SP |
| 79 | Negative Sequence Instantaneous Overcurrent | 50Q |
| 80 | Accidental Energization | 50/27 |
| 81 | Instantaneous / Time-delay Overcurrent Relay | 50/51 |
| 82 | Ct Trouble | 50/74 |
| 83 | Instantaneous Differential | 50/87 |
| 84 | AC (Alternating Current) Time Overcurrent Relay | 51 |
| 85 | Ground Time Overcurrent | 51G |
| 86 | AC (Alternating Current) inverse time overcurrent (locked rotor) protection relay | 51LR |
| 87 | Neutral Time Overcurrent | 51N |
| 88 | Phase Time Overcurrent | 51P |
| 89 | Locked / Stalled Rotor | 51R |
| 90 | Voltage Restrained Time Overcurrent | 51V |
| 91 | Negative Sequence Time Overcurrent | 51Q |
| 92 | AC circuit breaker | 52 |
| 93 | AC circuit breaker position (contact open when circuit breaker open) | 52a |
| 94 | AC circuit breaker position (contact closed when circuit breaker open) | 52b |
| 95 | Exciter (or) Dc Generator Relay | 53 |
| 96 | Turning Gear Engaging Device | 54 |
| 97 | Power Factor Relay | 55 |
| 98 | Field Application Relay | 56 |
| 99 | Short-Circuiting (or) Grounding Device | 57 |
| 100 | Rectification Failure Relay | 58 |
| 101 | Overvoltage Relay | 59 |
| 102 | Bank Phase Overvoltage | 59B |
| 103 | Phase Overvoltage | 59P |
| 104 | Neutral Overvoltage | 59N |
| 105 | Neutral Voltage Unbalance | 59NU |
| 106 | Auxiliary Overvoltage | 59X |
| 107 | Negative Sequence Overvoltage | 59Q |
| 108 | Voltage (or) Current Balance Relay | 60 |
| 109 | Neutral Current Unbalance | 60N |
| 110 | Phase Current Unbalance | 60P |
| 111 | Density Switch (or) Sensor | 61 |
| 112 | Time-Delay Stopping (or) Opening Relay | 62 |
| 113 | Pressure Switch Detector | 63 |
| 114 | Ground Protective Relay | 64 |
| 115 | Field Ground Protection | 64F |
| 116 | Rotor earth fault | 64R |
| 117 | Restricted earth fault differential | 64REF |
| 118 | Stator earth fault | 64S |
| 119 | Sub-harmonic Stator Ground Protection | 64S |
| 120 | 100% Stator Ground | 64TN |
| 121 | Governor | 65 |
| 122 | Notching or Jogging Device / Maximum Starting Rate / Starts Per Hour / Time Between Starts | 66 |
| 123 | AC Directional Overcurrent Relay | 67 |
| 124 | Ground Directional Overcurrent | 67G |
| 125 | Neutral Directional Overcurrent | 67N |
| 126 | Earth fault directional | 67Ns |
| 127 | Phase Directional Overcurrent | 67P |
| 128 | Sensitive Ground Directional Overcurrent | 67SG |
| 129 | Negative Sequence Directional Overcurrent | 67Q |
| 130 | Blocking Relay / Power Swing Blocking | 68 |
| 131 | Permissive Control Device | 69 |
| 132 | Rheostat | 70 |
| 133 | Liquid Switch and Level Switch | 71 |
| 134 | DC Circuit Breaker | 72 |
| 135 | Load-Resistor Contactor | 73 |
| 136 | Alarm Relay | 74 |
| 137 | Position Changing Mechanism | 75 |
| 138 | DC Overcurrent Relay | 76 |
| 139 | Telemetering Device; Speed Sensor | 77 |
| 140 | Phase Angle Measuring (or) Out-of-Step Protective Relay | 78 |
| 141 | Loss of Mains | 78V |
| 142 | AC Reclosing Relay / Auto Reclose | 79 |
| 143 | Liquid or Gas Flow Relay | 80 |
| 144 | Frequency Relay | 81 |
| 145 | Over Frequency | 81O |
| 146 | Rate-of-Change Frequency | 81R |
| 147 | Under Frequency | 81U |
| 148 | DC Reclosing Relay | 82 |
| 149 | Automatic Selective Control (or) Transfer Relay | 83 |
| 150 | Operating Mechanism | 84 |
| 151 | Pilot Communications, Carrier (or) Pilot-Wire Relay | 85 |
| 152 | Lock-Out Relay; Master Trip Relay | 86 |
| 153 | Differential Protective Relay | 87 |
| 154 | Bus Differential | 87B |
| 155 | Generator Differential | 87G |
| 156 | Generator / Transformer Differential | 87GT |
| 157 | Segregated Line Current Differential | 87L |
| 158 | Ground Line Current Differential | 87LG |
| 159 | Motor Differential | 87M |
| 160 | Overall Differential | 87O |
| 161 | Phase Comparison | 87PC |
| 162 | Restricted Ground Fault | 87RGF |
| 163 | Stator Differential | 87S |
| 164 | Percent Differential | 87S |
| 165 | Transformer Differential | 87T |
| 166 | Voltage Differential | 87V |
| 167 | Auxiliary Motor (or) Motor Generator | 88 |
| 168 | Line Switch | 89 |
| 169 | Regulating Device | 90 |
| 170 | Voltage Directional Relay | 91 |
| 171 | Voltage & Power Directional Relay | 92 |
| 172 | Field-Changing Contactor | 93 |
| 173 | Tripping (or) Trip-Free Relay | 94 |
| 174 | For specific applications where other numbers are not suitable | 95 |
| 175 | Transmitter | 96 |
| 176 | For specific applications where other numbers are not suitable | 97 |
| 177 | For specific applications where other numbers are not suitable | 98 |
| 178 | For specific applications where other numbers are not suitable | 99 |
