On Delay Timer Connection Diagram and Testing

In this article, we are going to see the On Delay Timer Connection Diagram. Also, we will test how it works. Basically, the on-delay timer has NO and NC contacts. So when we give the power supply to the timer it instantly does not do anything. After setting the time it makes its NC contacts into NO and NO contacts into NC. Suppose we have a set time delay of 20 sec, so after 20 sec of giving power supply to the timer, it interchanges its NO and NC contacts. The On Delay Timer has so many applications one of them is Star Delta Starter. 

First of all, let's see the function of each terminal of the on-delay timer.

On Delay Timer Terminal Diagram

Here, you can see the terminal diagram of on delay timer in the below figure.

Here, you can see a total of eight terminals is there. A1 and A2 are the coil terminals across them we have to connect a 230V AC power supply.

15, 16, and 18 terminals we can use for our applications. 15 is the common terminal and 16 is NC and 18 is NO.

Here, 25, 26, and 28 are not connected anywhere. But in some Timers, 25 is common, 26 is NC, and 28 is NO. So we can use these also like 15, 16, and 18. 

Now let's see the connection.

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On Delay Timer Connection Diagram

You can see in the above figure, that the connection diagram of Timer is for understanding the working principle. See, we have connected the 230V AC supply across the A1 and A2 terminals.

The Red colour indication lamp is also connected across the A1 and A2 terminals to indicate whether the power supply is available or not.

The green colour indication lamp is connected to the 16 or NC terminal of the Timer.

The yellow colour indication lamp is connected to the 18 or NO terminal of the Timer.

The neutral of all the lamps is connected to the neutral of the main power supply.

The common terminal or 15 of the timer is connected with the A1 terminal so it also gets the 230V power supply.

Now, let's start the test to understand how it is working.

Step 1

The main power supply is off condition, so all lamps are also off condition. Now we set the time delay to 40 sec.

Step 2

Now we turned on the main power supply, so the red indication lamp is turned on. Also, the green indication lamp is turned as it is connected to the NC terminal.

Now, you can see after 40 sec. the green indication lamp turned off and the yellow indication lamp turned on. So, it means that after 40 sec. the timer made the changeover, it made its NC contact into NO and NO contact into NC.

So, now you may understand the working principle and connection diagram of the timer. Now, you can connect a delay timer to any circuit easily.

Read Also: 

• On Delay Timer Connection with Contactor
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