Symbol |
Name |
Description |
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Relay Contact | Shown with relay in de-energized or in reset position. (Show relay coil designation near contact.) |
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Timing Relay Contact | TDC indicates contact closes at end of timing period. TDO contact opens at end of timing period. |
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Coil |
Relay, contactors, circuit breaker, solenoid etc. (Show device designation, X1) |
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Coil | Timing Relay – TDPU indicates timing period starts when coil is energized. TDDO indicates timing period starts when coil is de-energized. |
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Latching Relay or Mechanically Contractor | O=Operate; R=reset; TC=trip coil; CC=closing coil. (Coils may be seperated on diagram) |
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Knife Switch | If shown closed, terminals must be added. |
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Switch – General | Single pole, single throw. |
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Switch | One pole of multi-pole switch shown. Other poles shown elsewhere. |
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Pushbutton | Momentary or spring return. Single Circuit(make) |
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Pushbutton | Momentary or spring return. Single Circuit(break) |
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Pushbutton | Momentary or spring return. Two Circuit. |
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Pushbutton | Maintained, two circuit. |
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Pushbutton | Maintained, single circuit. |
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Selector Switch | Two position, maintained designate position shown; ie. A=Auto; |
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Selector Switch |
Three position, SR indicates spring return from position so labeled. “TRIP-NORMAL-CLOSE position shown. |
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Limit Switch | Normally open – not applicable for Motor Operated Valves and Solenoid Valves. |
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Limit Switch | Normall closed – not applicable for Motor Operated Valves and Solenoid Valves. |
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Used with other symbols to indicate device is adjustable | |
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Polarity Markings | Direct current. |
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Instantaneous Polarity Markings | |
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3-phase, 3-wire, delta | |
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3-phase, 3-wire, open delta grounded | |
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3-phase, 3-wire, wye | |
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3-phase, 3-wire, wye grounded neutral | |
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3-phase, 3-wire, zigzag | |
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3-phase, 3 wire zigzag, grounded neutral | |
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Connection to earth ground | may be plant grounding system |
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Connection to chassis or frame | |
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Terminal | may be added to any of the following symbols at connection points. |
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Short circuits | (not a fault) |
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Terminal | designates termination of field run cables to main control board, main control board termination cabinet or emergency power board termination cabinet. |
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Flow Switch | Closes on increase in flow at value shown. |
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Flow Switch | Opens on increase in flow at value shown. |
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Flow Switch | Closes on decrease in fow at value shown. |
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Flow Switch | Opens on decrease in flow at value shown. |
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Liquid Level Switch | Opens on rising level (Closes on low level) |
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Liquid Level Switch | Closes on rising level (Opens on low level) |
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Pressure or Vacum Switch | Closes on rising pressure switch. |
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Pressure or Vacum Switch | Opens on rising pressure (Closes on increase in vacuum) |
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Temprature Switch | Closes on increasing tmp. |
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Torque Switch | Opens on high torque. |
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Transductor | Control winding shown with 5 loops. Power winding shown with 3 loops. |
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Transformer | General, two winding |
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Autotransformer | General |
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Transformer | General, three winding |
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Current Transformer | number represents quantity |
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Bushing Type Current Transformator | |
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Potential Transformer | Number represents quantity |
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Fuse | General |
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High Voltage Primary Fuse Cutout | |
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Lighting Arrester | General Gap Type |
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Lighting Arrester | Valve or film type |
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Circuit Breaker | General |
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Power Circuit Breaker | Show location of operating mechanism |
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Circuit Breaker | 3-pole with magnetic – overload device in each pole. |
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Circuit Breaker | 3-pole, drawout type (Used in metal clad switchgear groups) |