Description
A single-line electrical symbol legend covering line types, ANSI switchgear device numbers and three-phase transformer connections, each symbol or device number paired with its function. A handy reference for single-line diagrams, protection schedules and switchgear documentation. A free AutoCAD DWG file download.
Symbols shown:
Line symbols:
- Conductor
- Underground conductor
- Overhead conductor
- Tripping or interlocking circuit
- Equipment outline
- Key interlocking
Switchgear device numbers and functions:
- 15 - Synchronization check relay
- 27 - AC under voltage
- 32 - Directional power relay
- 40 - Loss of field protection relay
- 46 - Phase balance current relay
- 47 - Phase sequence relay
- 48 - Incomplete sequence relay
- 49 - AC thermal overload relay
- 50 - AC instantaneous overcurrent relay
- 51 - AC time delay overcurrent relay
- 52 - AC circuit breaker
- 59 - AC over voltage relay
- 63 - Sudden pressure relay
- 78 - Phase angle measuring relay
- 81 - Under frequency relay
- 86 - Lockout relay
- 87 - Differential current relay
- 92 - Reverse power relay
- Specialized relay function suffix (e.g. S - stall, G - ground, T - temperature)
Other symbols:
- Resistor
- Thermistor
- Delta transformer connection
- Wye / star with solid grounded neutral
- Wye / star with resistance grounded neutral and maximum current indicated
- Feeder identification symbol
