NO and NC Switch Working Principle

Uses of NO and NC Contacts


 In all control panel circuits and automation systems, the operation is based on the open or closed state of the switches, sensors, electromagnetic contacts or relays.  So it is imperative to know the concept behind NO / NC.  Normal Open (NO) and Normal Close (NC) are terms used to define the actual state of its switches, sensors or relay contacts.


NO and NC Switches Working in a Contactor



 NO and NC are an essential part of an automation system.  An example of this is a limit switch, in which one side is always NC and the other is NO.  It is a work in mechanical energy.  Similarly, a large number of NO / NC elements running in electrical or mechanical energy are used in the automation system.  For example, there are many devices that can be viewed, such as motor control panels and remote Doors.  An example of the function of an NC contact is to light the inside of the car door.

What is NO contact?


 A contact, or an open contact in general, is an open contact until a certain contact is completed. For example, let us consider a limit switch.  A limit switch has at least one contact with NO / NC.  Any contact on the limit switch will be remain open or close until its actuator is pressed.  Pressing the actuator closes the contact and starts the operation.  In the case of a proximity switch, as in the case of a pressure switch, the contact remains open until the object is felt and the preset pressure level is reached.

 The image below shows the Normal Open (NO) contact state of a push-button when it is in normal condition and pressed.

https://youtu.be/FPbRxkYANOw

What is NC Contact?


 An NC contact or a normally closed contact is the exact opposite of a NO (Normal Open) contact.  It will be always remain closed until a pressure reaches this.  Example: When an electrical contactor is used in a circuit, it remains in the Normally Close (NC) until the electrical energy reaches the Contactor magnetic coil.

The image below shows the Normal Close (NC) contact state of a push-button when it is in normal condition and pressed.

https://youtu.be/FPbRxkYANOw

Limit Switch NC (NC)

 Let us discuss the function of the limit switch in the case of mechanical energy.  The NC contact of a limit switch, when used in a circuit, will break the circuit or current flow when its actuator is pressed.  Similarly, when a coil is not activated when using a relay, its contacts are closed.

Click here and watch Video Tutorial for NO, NC contact

Working NO and NC in a Push Button

 The image above shows the NO and NC configuration of a contactor.  NC contacts are normally closed, which means that they remain switched on until the button is pressed.  When the push button is pressed it opens the conductor.

 NO Contacts are usually open contacts, which act as a switch (push) when the push button is pressed.

 Hope you will understand what is said.  If this helps you, subscribe and if you have any questions please comment below.  Thank you for reading this article.


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