Switches

Instrumentation Switches used in measurement and control systems. The purpose of a switch is to turn on and off with varying process conditions.

What is mean by Switch?

An electromechanical device used to connect or disconnect a circuit is known as switch.

Switch divide in two parts

• Pole
• Throw

Pole- what the switch armature is connected to throw

Throw- the closed position of the switch

Basic Switch Function 

Open and close circuit:

Open (no connection)

Closed (connection)

Switch Contacts:

Normally-open (NO) 

Normally-closed (NC)

Basic Switch Types

• Single Pole, Single Throw (SPST)
• Single Pole, Double Throw (SPDT)
• Double Pole, Single Throw (DPST) 
• Double Pole, Double Throw (DPDT)

Types of switches

• Toggle switch 
• Push button
• Drum switch
• Limit switch
• Temperature switch
• Pressure switch
• Rocker Switch
• Level switch
• Flow switch
• Slide switch
• DIP switch
• Rotary switch
• Thumbwheel switch
• Selector switch