How to Test 24v Transformer with Multimeter?

What is transformer testing?

The transformer is a device that is used to transfer energy from low voltage to high voltage or high voltage to low voltage. Generally, transformer primary and secondary winding depend on the number of turns of the transformer winding. However, though transformer is an electromechanical and high efficient device. Sometimes fault occurs in the transformer if a fault occurs then transformer efficiency becomes reduced. For this reason, the transformer test is crucial thing. Transformer tests can be done in various ways. However, we will see here how to test 24v transformer with multimeter. It is noted that both types of transformers (low-voltage and high-voltage) transformer test is almost the same.  

How to check 24v transformer?

We know well that the transformer has two portions primary and secondary winding. If we would like to test a transformer then we have to do it wising both windings. However, there is a well-known question about how to test low-voltage transformers. Don’t worry, we are going to share three methods to test the 24v transformer with three different methods.

test transformer with multimeter

First of all, let’s see how to test 24v transformer with multimeter. In this case, you will need a multimeter and you have to select a multimeter probe at a 200-ohm point. It is noted that you can have a question that how to test 12v transformer with multimeter. The straightforward answer, you can follow the same way for the 12v transformer that we will show here.

1st method

Now connect your multimeter’s positive and negative probe with two terminals of the transformer’s primary winding. It is noted that low voltage primary winding becomes red color. However, connect your multimeter’s positive and negative probes with the two terminals of the primary winding. If your multimeter shows the approximate ohm that you want then you can confirm that your transformer is eligible to use.

You can check it in the same way by connecting with the multimeter positive and negative probe and two terminals of the transformer secondary winding. In this case, you will see that your meter is showing a minimum ohm. If this happens then you can be confirmed that your transformer is eligible to use.

Second method

In this case, you need to connect the primary winding two terminals with the neutral and line terminal. Now take a digital multimeter and select its nob in the AC mode and connect your digital multimeter probe with the transformer secondary winding two terminals. In this case, you will see that your meter is showing the approximate voltage that you need to make the transformer prove eligible to use.

Third method

In this case, you should connect the primary winding two terminals with the neutral and line terminal. Connect transformer secondary winding with any device so that you get output. In this case, you may choose a small bulb. Now connect the transformer secondary winding two terminals (coil terminals) with bulb two terminals. If your bulb blazes then you can make sure that your transformer is good to use. This method is called the shunt method. However, these three tests are the simple test for the low-voltage transformer (24v, 12v, etc.). You may easily do it from your home.  

How to test a 24v transformer?

We need to check the transformer to be confirmed that the transformer is functioning and it has no chance to be a failure during operation. It is because we know that transformers perform a crucial role in distributing electrical power safely. However, we have told you before low voltage transformer test is simple. We have shown three methods to check the transformer. If you would like to test a 24v transformer or 12v transformer then you may easily use such a method. So, follow the above instruction to test your crucial transformer.

How to test power transformer?

We know well, transformer faults can cause enhance the transformer winding resistance which is very harmful and the transformer may explode. However, the winding resistance test of the transformer includes assessing the condition of high voltage (LV) and low voltage (LV) windings. It is noted that winding resistance can be measured by using the current-voltage method. In this case, the current is applied to the winding, and the voltage drop in the winding is measured by using V = IR (Ohms law). You can test an electrical power transformer by using a multimeter.

power transformer testing

It is a very simple process. On the other hand, if you would like to test a high-voltage power transformer then you have to take some steps and it is a difficult process. However, we are going to discuss a high-voltage transformer test with a multimeter. In this case, you need a digital multimeter and apply some techniques. Let’s see what we need to apply for and conduct the winding resistance test procedure. First of all, we will test transformer winding resistance.

First of all, connect testing leads to the tester (Special note: This high voltage transformer rating 315 KVA, step down transformer 11 KV/400V, Dyn11, Ir (HV) = 16.53A, Ir (LV) = 410A).

  1. Connect the transformer earth with the tester earthing connection.
  2. Connect tester 1.1 lead to the High Voltage (HV) windings ‘’U’’ terminal
  3. You must connect tester 1.2 lead to HV windings ‘’V’’ terminal
  4. Connect the tester earth connection with the transformer earth.
  5. Now you have to connect tester 2.2 lead to the low voltage (LV) windings ‘’N’’ terminal and connect tester 2.1 lead to LV windings U terminal.
  6. If the connection becomes completely done then start testing.
  7. You should write down the reading that is shown by the tester, such as (Nu = 44.075, Uv = 3.24 ohm, etc.).
  8. After writing a reading you can change the connection lead to take another reading. Now connect tester 1.2 lead to HV winding ‘’W’’ terminal and connect 1.1 lead to HV windings ‘’V’’ terminal.
  9. Connect tester 2.1 lead to LV windings ‘’V terminal and connect 2.2 lead to LV windings ‘’N’’ terminal.
  10. If all the connections become successfully done then start testing.
  11. Write down all the readings, such as Nv = 44.095, VW = 3.2 ohms, etc.
  12. After taking this reading, you can change and connect tester 1.1 lead to the HV windings ‘’ W’’ terminal, and connect 1.2 lead to the HV windings ‘’U’’ terminal.
  13. Connect tester 2.1 lead to LV windings ‘’W’’ terminal, and connect tester 2.2 lead to LV windings ‘’N’’ terminal.
  14. After completing all the connections, you can start testing. In this case, you will get some reading and write down that like (Nw = 44.139, UW = 3.29 ohm, etc.).
  15. Now switch off the tester, and remove the tester connection from the transformer terminals.

Final thought of how to test 24v transformer with multimeter

Indeed magnetic balance test of power transformer is done only for the three-phase transformer to detect the fault in the transformer core and identify the transformer inter-turn fault. On the other hand polarity test of transformers is also an important test. This test is done to identify the induced voltage direction in the windings.

However, we should check or test the transformer before operation. It is because the transformer plays a crucial role in the power supply and distribution. We have shown above how to test 24v transformer with multimeter and we have also shown how to test a high-voltage power transformer. We hope that will help you a lot to test your transformer.  

Leave a Comment