Normally Open Relay Switch

Of these the following are commonly encountered.

Normally open relay switch.

The contacts are normally closed and open when the switch is actuated. The contacts are normally open and close when the switch is actuated. In other words when voltage is applied to the relay contactor terminals this contact closes. 1no1nc is generally used to describe contactors industrial power relays and manual switches like emergency stop buttons.

The no normally open spst single pole single throw relay has an opened circuit state when no current is applied to its coil so basically it disconnects the power to the load in the inactive state. Normally open no contacts allow current when the relay or contactor is energized. Normally closed nc contacts allow current through when the relay or contactor is not energized. Relays and contactors have two types of contacts each suited for different applications.

We can tell this switch is a normally open no switch because it is drawn in an open position. 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. No is normally open i e. Nc is normally closed i e.

Now let s go through a real world example of normally open and normally closed contacts that we are all familiar with. Of these contact forms the following are particularly common. 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. Ehdis 2 pack car truck motor heavy duty heavy duty 5 pin 80a 12v on off normally open spdt relay socket plug 5 wire automotive 4 4 out of 5 stars 217 12 99 12.

Form a contacts make contacts are normally open contacts. 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.