There are two types of contacts no normally open and nc normally closed.
Normally open auxiliary contact symbol.
When voltage is applied this contact opens and interrupts current.
In other words when voltage is applied to the relay contactor terminals this contact closes.
These have two states on or off.
Jic nfpa sample drawing.
Normally open terminal normally closed terminal and common terminal respectively.
A limiting condition is wired through the coil contacts and resulting conditions are wired through the.
These terminals are usually labelled as normally open common and normally closed no c nc.
On the other hand contact point a contact point b and contact point c represent contact structures.
These are known as normally closed n c and normally open n o contacts.
We can tell this switch is a normally open no switch because it is drawn in an open position.
There are two basic auxiliary contact types.
It consists of a coil and a number of auxiliary normally open or normally closed contacts.
Form c contacts change over or transfer contacts are composed of a normally closed contact pair and a normally open contact pair that are operated by the same device.
These are contacts of relays contactors timers counter field instrument switches pressure switches limit switches etc.
Auxiliary contact 1nc 1no.
Those that are closed in the non activated state or those that are open.
A form c would have 3 leads and would have 1 normally open and 1 normally closed circuit.
This is also called a changeover device because the common contact changes from the normally closed position to the normally open position when the coil is energized in a relay or a magnetic field is nearby in a reed switch.
No terminal nc terminal and com terminal represent contact terminals symbols.
There is a common electrical connection between a contact of each pair that results in only three connection terminals.
The n c contacts are for example used as electrical interlocks where two contactors are used for forward reverse operation.
Available in svg png.
Each symbol means a single terminal itself.
Auxiliary contact 1nc 1no.
Normally closed nc contacts allow current through when the relay or contactor is not energized.
Normally open no contacts allow current when the relay or contactor is energized.
Output coil can be auxiliary contactor or main contactor coil.
Auxilliary contacts symbols for use in electrical pneumatic and hydraulic schematic diagrams.
