What is DPST Relay? Double Pole Single Throw Relay

A DPST Relay or Double Pole Single Through Relay is a type of relay that has two inputs and two outputs. Each input has corresponding one output. Including the coil terminals, it has a total of six terminals. The DPST relay can control two different electrical or electronic circuits without any connection between them. For example, input 1 only be connected or disconnected to output 1, and input 2 only connected or disconnected to output 2. The input 1 will never be connected to the output 2 and the input 2 will never be connected to output 1.

The DPST Relay cannot provide the signal routing function it just provides the switching or On/Off function. the DPST relay is the combination of two SPST Relay having a single coil. Both of the contacts of the DPST Relay operate simultaneously. That means when the coil of the relay is not energized the both of the inputs are disconnected from their corresponding outputs but when the coil of the relay is energized both of the inputs will be connected to their corresponding output at the same time.

Here, you can see the symbol of the Double Pole Single Throw or DPST Relay.

Now, let's see the connection diagram of DPST Relay to understand its working principle.

Here, we used a NO type DPST Relay. You can see the coil of the relay is connected to the battery in series with a switch S1. The two individual contacts of the relay are connected with two different circuits. The first circuit consists of LED1 and Battery 1 while the second circuit is consists of LED2 and Battery 2.

When switch 1 is in off condition, the coil of the relay will not get any power supply so both of the contacts of the Relay will be in off condition and both LEDs will be in off condition. When the switch 1 is turned on, the coil of the relay will be energized and both of the contacts will be closed at the same time. So both of the LEDs will be glow together.

There are not so much applications of DPST Relay. In some special electronic circuits, they are used.

Read Also: 

• What is SPST Relay? Single Pole Single Throw
• What is SPDT Relay? Single Pole Double Throw
• What is DPDT Relay? Double Pole Double Throw
• What is Relay Switch? Circuit Diagram and Working Principle
• Working Principle of Static Relay with Block Diagram

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