How Do You Know if the Transformer Is Bad

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Transformers are an electric component that transmit electrical energy between at least two circuits. Transformers regulate the voltage in circuits, but in some cases these can get bad and cause a excursion to non work. You'll demand to identify key data about your transformer, like whether it'due south suffered visible harm and what its inputs and outputs are. Later that, it should be relatively elementary to test the transformer with a digital multimeter (DMM). Should yous continue having problems with the transformer, you'll demand to troubleshoot it.

1. i

   Inspect the transformer visually. Overheating, which causes the internal wiring of the transformer to run at elevated temperatures, is a common cause of transformer failure. This frequently causes a physical deforming of the transformer or the area surrounding information technology.

   • If the transformer exterior is bulged or shows what appear to exist burn down marks, don't test the transformer. Instead, replace it.

2. two

   Decide the wiring of the transformer. The wiring should exist conspicuously labeled on the transformer. However, it is ever best to obtain a schematic of the circuit containing the transformer to determine how it is connected.

   • The schematic for the circuit will be bachelor in the production information or on the website of the circuit manufacturer.^[ane]

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3. 3

   Identify the transformer inputs and outputs. The first electrical excursion volition be connected to the chief of the transformer. This is its electrical input. The second circuit receiving ability from the transformer is connected to the transformer secondary, or the output.^[2]

   • The voltage being supplied to the primary should be labeled both on the transformer and the schematic.
   • The voltage being generated past the secondary should exist labeled in the aforementioned manner as the primary.

4. four

   Decide the output filtering. It is common to attach capacitors and diodes to the transformer secondary to catechumen the Air conditioning ability from the output to DC power. This information will not be available on the transformer label.^[3]

   • By and large, y'all can find the transformer conversion and output filtering information on the schematic.
   • Look for whether the transformer is AC or DC wherever the voltage is listed on the label.^[4]

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1. ane

   Fix to mensurate the excursion voltages. Turn off the ability to the circuit. Remove covers and panels equally necessary to gain access to the circuits that contain the transformer. Acquire a digital multimeter (DMM) to have the voltage readings. DMMs are available at electrical supply stores, hardware stores, and hobby shops.^[5]

   • Mostly, you'll need to attach the leads of your DMM to the input lines to verify that the primary of the transformer is not shorted. The aforementioned process will be used to check the transformer secondary.

2. 2

   Confirm the proper input to the transformer. Apply power to the circuitry. Use the DMM in AC mode to measure the transformer primary. If the measurement is less than 80 percent of the expected voltage, the mistake could lie in either the transformer or the circuitry providing the primary with power. In that case:

   • Separate the transformer from the input excursion. Test the input with your DMM. If the input power climbs to the expected value, the principal of the transformer is bad.
   • If the input power does not climb to the expected value, then the problem lies not with the transformer, just with the input circuitry.^[6]
   • The input and output on the transformer may be labeled with "input" and "output," or the input might be a black and white pigtail.^[7]
   • If the transformer has terminals, the input will usually exist L, which stands for "line," or hot power, and N, which stands for neutral, or the neutral power going into that wire. The output will be the depression voltage side.^[8]

3. three

   Measure the secondary output of the transformer. If at that place is no filtering or shaping beingness performed by the secondary circuitry, employ the Ac mode of the DMM to read its output. If there is, use the DC scale of the DMM.

   • If the expected voltage is non nowadays on the secondary, either the transformer or a filtering or shaping component is bad. Examination the filtering and shaping components separately.
   • If the testing of the filtering and shaping components show no problems, and so the transformer is bad.^[nine]

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1. 1

   Empathise the root of the problem. Transformer failure is usually a symptom of a different kind of failure somewhere in the electrical excursion. Transformers generally have long lives, and rarely burn out by themselves.^[10]

2. 2

   Observe replaced transformers. If the problem causing your transformer to brusk out is coming from elsewhere in your circuit, it's likely the transformer will burn down out once more. Subsequently you've replaced the transformer, discover it to make sure this does not happen. If it does, you'll need to perform boosted tests.

   • An overloaded transformer will often make snapping and crackling noises. If yous hear sounds like these, cut ability to the transformer to prevent burnout.^[xi]

3. 3

   Verify the status of external fuses, if necessary. If your transformer has an internal fuse, y'all may not have fuses in the line leading upward to the transformer. Otherwise, in that location should be fuses in the power supply line to the transformer. Bank check to make sure these are in adept condition and replace any that aren't working properly.

   • Blackness, melting, and deforming in fuses are good indications that the fuse has been damaged. Elementary remove and supplant these.
   • In some cases, it might be hard to tell if a fuse is in adept condition. Attach your DMM to the fuse with one lead on each fuse cease. If current runs through the fuse, information technology's expert.^[12]

4. iv

   Check for overdraw on your secondary. In some cases, the secondary of your transformer may be cartoon likewise much current, causing it to curt out. If you have a multi-tap transformer and y'all receive the reading "OL" from the secondary, it's probable the secondary is shorted.

   • Test this by hooking upward the secondary to its circuit and using your DMM to exam the secondary lines. If the reading is above the amperage rating for the transformer, the circuit is cartoon besides much power.
   • Many common transformers have 3 amp fuses. The amperage rating for your transformer fuse may exist labeled on the transformer, but will also be bachelor in the circuit schematic.^[13]

5. five

   Remove inputs and outputs to determine the source of the failure. For linear fuses, you'll simply take one input and output. In this example, your trouble is either coming from the input circuit or the output circuit. For more complex fuses, remove inputs and outputs to the transformer one past one to determine what component of the entire circuit is causing the short.^[14]

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Add New Question

• Question

  Where should I look to find the input and output of a transformer?

  

  Jesse Kuhlman is a Master Electrician and the Owner of Kuhlman Electrician Services based in Massachusetts. Jesse specializes in all aspects of abode/residential wiring, troubleshooting, generator installation, and WiFi thermostats. Jesse is also the author of four eBooks on home wiring including "Residential Electrical Troubleshooting" which covers basic electrical troubleshooting in residential homes.

  

  Primary Electrician

  Proficient Respond

  The input and output on a transformer is nearly ever going to exist labeled—commonly simply with "input" and "output."

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• A buzzing or not bad sound is frequently an early sign that a transformer is near to develop a burn.

• Practice not presume that the primary side and secondary side of the transformer are referenced to the same electrical ground. The transformer master and secondary are frequently referenced to different grounds. Be aware of this divide grounding while taking measurements.

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• While the circuits are exposed and energized for testing, adventitious contact with circuit ability could cause stupor or injury. Touch the excursion only with the probes of the DMM.

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Things You'll Need

• Schematic of the circuit
• Digital Multimeter (DMM)

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Commodity Summary X

To exam a transformer with a digital multimeter (DMM), start turn off power to the circuit. Next, attach the leads of your DMM to the input lines. Employ the DMM in AC mode to measure out the transformer primary. If the measurement is less than 80% of the expected voltage, your problem could be with the transformer or the circuitry providing the principal power. To measure out the secondary output, employ the Air conditioning way if there's no filtering or shaping. Otherwise, utilize the DC scale to make up one's mind what the issue is. To larn how to troubleshoot your transformer, proceed reading!

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Source: https://www.wikihow.com/Test-a-Transformer