Description
A schematic (ladder-diagram) electrical symbol legend for control drawings, pairing each symbol with its name. It covers relay coils, normally-open and normally-closed contacts, time-delay contacts, process switches, pushbuttons, selector switches, and wiring and terminal types. A handy key for control and instrumentation schematics. A free AutoCAD DWG file download.
Symbols shown:
- Control relay (typ.) coil
- Motor control relay (typ.) coil
- Time-delay relay (typ.) coil
- Normally-open (N.O.) contact
- Normally-closed (N.C.) contact
- Time delay close on energize
- Time delay open on energize
- Time delay open on de-energize
- Time delay close on de-energize
- Level switch (N.C.)
- Level switch (N.O.)
- Flow switch (N.C.)
- Flow switch (N.O.)
- Pressure switch (N.C.)
- Pressure switch (N.O.)
- Temperature switch (N.C.)
- Temperature switch (N.O.)
- Vibration switch (N.C.)
- Vibration switch (N.O.)
- Limit switch (N.C.)
- Limit switch (N.O.)
- Switch function descriptor convention (first to fourth letter)
- Momentary pushbutton (N.C.)
- Momentary pushbutton (N.O.)
- 2-position maintained selector switch
- 3-position maintained selector switch (Hand-Off-Auto)
- Fuse
- Breaker
- Panel wiring
- Field wiring
- Control panel terminal
- MCC terminal
- Field terminal
- Switch gear
- Equipment control panel
- Field junction box terminal
