Normally open no contacts allow current when the relay or contactor is energized.
Electrical symbol normally open contact.
Normally closed nc contacts allow current through when the relay or contactor is not energized.
Also now is a good time to remind you that this is article is talking about the electrical normally open and normally closed symbols which while may look the same as the ladder logic xic and xio instructions are not the same.
Relays and contactors have two types of contacts each suited for different applications.
There is a common electrical connection between a contact of each pair that results in only three connection terminals.
Some of the most common and widely used symbols are given below 1.
Are electrical electronic or mechanical devices designed to interrupt or divert the flow of electric current or other signals in an electrical circuit.
The lamp will energize only if someone presses the switch holding its normally open contacts in the closed position normally open switch contacts are sometimes referred to in the electrical industry as form a 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.
Most of the time a small voltage or current is used to switch other voltages or higher currents that may be electromechanical or fully electronic type.
Auxilliary contacts symbols for use in electrical pneumatic and hydraulic schematic diagrams.
The switches pushbuttons circuit switches.
The relay are switching devices activated by signals.
Relay symbols and electromagnets.
We can tell this switch is a normally open no switch because it is drawn in an open position.
Changeover contact this is the changeover contact of a relay that is closed or connected with one terminal known as normally closed terminal when the relay is deactivated the other terminal is open known as normally open terminal.
Symbol of switches push buttons circuit switches.
Normally closed contact in the following illustration when the relay is de energized the example normally closed contacts are shown as closed and are not highlighted.
If the contact is normally open it would not allow any current to pass through it and hence there will be an open circuit at this contact.
These terminals are usually labelled as normally open common and normally closed no c nc.
It is the contact of relay that is in closed position when there is no power supplied.
In other words when voltage is applied to the relay contactor terminals this contact closes.
A complete path of current exists at this time and the light is on.
The given symbol indicates a normally open contact.
That is all there is to it.
This symbol is used to indicate normally close contact.
Don t overthink these two concepts.
