NO
Normally open contact
A contact shown open in the normal state defined for its device.
Schematic
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1095 entries · Original illustrations
Control circuits
NC
Normally closed contact
A contact shown closed in the normal state defined for its device.
Schematic
CO
Changeover contact
A contact arrangement switching a common connection between two contact paths.
Schematic
Coil
Relay coil
The operating element associated with a relay and its separately drawn contacts.
Schematic
KM
Contactor
An electrically operated switching device commonly used for repeated switching duties.
SLD / Schematic
PB NO
Normally open pushbutton
A pushbutton contact normally shown open before actuation.
Schematic
PB NC
Normally closed pushbutton
A pushbutton contact normally shown closed before actuation.
Schematic
E-stop
Emergency-stop operator
An identified emergency-stop operator and its documented contact arrangement.
Schematic
SS
Selector switch
An operator switch selecting between documented control positions.
Schematic
Lamp
Indicator lamp
A visual indicator associated with a documented control or equipment condition.
Schematic
PLC I/O
PLC input / output
A controller interface point connecting field signals to an identified module channel.
Schematic
R
Resistor
A resistive component with its value and purpose documented separately.
Schematic
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