In this post, we will discuss the Pressure Switch, its working, and connections. This post will help you to understand the concept of the Pressure switch, Also this post will help you to work with a pressure switch practically.

Pressure Switch

A pressure switch is a form of switch that makes electrical contact when a certain set pressure has been reached on its input. This is used to provide on/off switching from a pneumatic or hydraulic source. The switch may be designed to make contact either on pressure rise or on pressure fall.

This is a device designed to monitor a process pressure and provide an output when a set pressure (setpoint) is reached. A pressure switch does this by applying the process pressure to a diaphragm or piston to generate a force which is compared to that of a pre-compressed range spring.

Pressure Switch has 3 contacts.

Common

NO (Normally Open)

NC (Normally Closed)

A spring is used in pressure switch when pressure increases this spring comes in tension. A pressure is also set using adjusting screw when increasing or decreasing pressure comes to this pressure contact changes from NC to NO or from NO to NC.

A differential pressure is also used In pressure Switch. In this pressure Switch, two Pressures are used.

1.Differential Pressure.

2.main Pressure.

Let Suppose main Pressure is 4kg/cm^2 and Differential Pressure is 1 kg/ cm^2, then on increasing pressure contact will change from NC to NO at 5 kg/cm^2 and on decreasing pressure from NO to NC at 3 kg/cm^2.

The connection of a Pressure Switch

2 wires are connected in a pressure switch

One is connected in common and other is connected in NO or NC according to the application.

How to check a pressure switch

• Step 1: first we check the continuity between common between normally closed (NC).
• Step 2: Now after increasing the pressure when pressure is equal to set pressure we check the continuity between common and normally open (NO).
• Step 3: now we will decrease the pressure and when decreasing pressure is equal to the set pressure again we will get continuity between common and normally closed (NC).

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