Normally Open Relay Contact Symbol

It is the contact of relay that is in closed position when there is no power supplied.

Normally open relay contact symbol.

In other words when voltage is applied to the relay contactor terminals this contact closes. Normally closed nc contacts allow current through when the relay or contactor is not energized. 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. Normally open no contacts allow current when the relay or contactor is energized.

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. Now let s go through a real world example of normally open and normally closed contacts that we are all familiar with. Relay symbols and electromagnets. The contacts open when the relay activates to break the circuit.

Time delay relay contacts must be specified not only as either normally open or normally closed but whether the delay operates in the direction of closing or in the direction of opening. Of these contact forms the following are particularly common. The following is a description of the four basic types of time delay relay contacts. Relays and contactors have two types of contacts each suited for different applications.

Rarely are these familiar examples good for learning but a 3 way switch is an excellent example of using normally open and normally closed switches. The relay are switching devices activated by signals.