Normally Open Relay Contact Symbol

The national association of relay manufacturers and its successor the relay and switch industry association define 23 distinct forms of electrical contact found in relays and switches.

Normally open relay contact symbol.

The relay are switching devices activated by signals. In other words when voltage is applied to the relay contactor terminals this contact closes. Now let s go through a real world example of normally open and normally closed contacts that we are all familiar with. The contacts open when the relay activates to break the circuit.

Normally open no contacts allow current when the relay or contactor is energized. Of these contact forms the following are particularly common. First we have the normally open timed closed notc contact. Relay symbols and electromagnets.

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. Normally closed nc contacts allow current through when the relay or contactor is not energized. 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. 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 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.