Troubleshooting Your Transformer
- Understand the root of the problem. Transformer failure is usually a symptom of a different kind of failure somewhere...
- Observe replaced transformers. If the problem causing your transformer to short out is coming from elsewhere in your...
- Verify the condition of external fuses, if necessary. If your transformer has an internal...
- Use your multimeter and measure this voltage at the appropriate terminals.
- If there's no voltage on this side of the transformer, check the breaker and all wiring entering the unit for loose connections, corrosion, damage.
How to troubleshoot a transformer that does not work?
1 Separate the transformer from the input circuit. ... 2 If the input power does not climb to the expected value, then the problem lies not with the transformer, but with the input circuitry. 3 The input and output on the transformer may be labeled with "input" and "output," or the input might be a black and white pigtail. ... More items...
How do you know if your HVAC transformer is bad?
There are a few things that indicate a terrible HVAC transformer, including the following: 1. Vibrating And Humming – The humming noise that transformers make is reasonable. This sound is produced to the contraction and expansion of the iron core or the laminations.
How do I troubleshoot a broken transformer probe?
Make sure the probe on the transformer case is touching bare metal and not resting on some type of finish that may act as an insulator. Scratch the probe tip back and forth until it makes contact with base metal.
What should I do if my transformer is bulging?
If the transformer exterior is bulged or shows what appear to be burn marks, don't test the transformer. Instead, replace it. Determine the wiring of the transformer.
How do you diagnose a bad transformer?
You can do a quick test for each winding for an open while the transformer is still connected in a circuit. Assuming you're using a cheap inaccurate ohm meter. Look for a reading of somewhere between one and about 10 ohms. If any winding reads higher than 10 ohms you have probably found a bad transformer.
What are the methods of troubleshooting a transformer?
How to Troubleshoot a Low-Voltage TransformerIdentify the transformer's terminals, using its label as a guide. ... Turn a multimeter to its VAC function. ... Test the transformer's input voltage with the multimeter, using the transformer's label as a terminal guide. ... Test the transformer's output voltage with the multimeter.More items...
How do you tell if a transformer is shorted?
A suspected short can be checked with an ohmmeter across the secondary winding with the source and load disconnected. If there is a short, the meter will read 0 Ω. Again the meter should be on a low scale.
What happens when transformer goes bad?
If your transformer is bad, you will have a tripped circuit breaker. It tips to prevent a voltage surge which can fry various parts inside the HVAC system resulting in a major breakdown of the equipment. Similarly, a transformer with clear burn marks or a bulged exterior is also a sign of a bad transformer.
How do you test a transformer?
You can test any transformer, including a phone charger transformer, using a multimeter. In output transformer testing, you use the voltmeter setting to check the output voltage while the transformer is connected to power.
What are the causes of transformer failure?
The most common cause of failure of transformer is insulation failure; it deteriorates due to heat, oxidation, acidity and moisture. Line surges such as switching surges, voltage spikes, line faults and distribution abnormalities.
How do you test a transformer with a digital multimeter?
To do this, first set your meter to read AC voltage (not DC). Then connect the black lead from your meter to one of the output terminals on the transformer and use an alligator clip or other similar device to connect it securely. Next, touch both probes together and set your meter to read resistance (ohms).
How do you test a transformer for continuity?
0:091:46Transformer Continuity - YouTubeYouTubeStart of suggested clipEnd of suggested clipFirst we need to test continuity across the primary winding to do this take one probe and touch theMoreFirst we need to test continuity across the primary winding to do this take one probe and touch the h1 bushing and touch other probe to the h2 bushing.
How do I know if my transformer is working?
To test your transformer, simply touch the red and black pins of your ohmmeter to the opposite ends of the transformer's wiring. Read the display and compare the resistance on your ohmmeter to the resistance stated on the transformer's data sheet. This is sometimes listed on the transformer's enclosure.
How do you know if a transformer blew?
When a transformer fails, it will usually result in a loud boom, a power outage, and a fireball that creates a large plume of smoke.
What is a low voltage transformer?
A low-voltage transformer taps into a home's high-voltage power supply and produces a safe, low-voltage electrical feed. Low-voltage transformers do not wear out. A technician should troubleshoot the transformer and find the reason it failed before replacing it. Usually, a transformer fails only after another part in the electrical circuit shorts ...
What happens if the input voltage is correct?
If the input voltage has a correct reading, but the output voltage has a high or low reading, the secondary windings have a fault. The transformer must be replaced. If the input voltage has a correct reading, but the transformer does not produce any output voltage, check the transformer's secondary windings for continuity.
What is the label on a transformer?
Identify the transformer's terminals, using its label as a guide. Transformers contain input, known as the "primary," and output, known as the "secondary," terminals . The transformer's label identifies the input (high voltage) and the output (low voltage) sides, along with the input and output voltages -- measured as voltage-alternating-current (VAC) -- and their corresponding terminals.
What to do if multimeter does not read continuity?
Replace the transformer. If the multimeter does read continuity, re-connect the input wires.
When rewinding a transformer, should the coils be pressed down?
During manufacturing/ rewinding of the transformer, the coils should be pressed down, heated and cooled repeatedly until the coil height stabilizes. The winding pressure bolts and core clamping bolts should be tightened during the first periodical overhauling after commissioning to take care of shrinkage.
What does it mean when oil shows a low break down voltage?
Internal Flashover. If the oil shows a low break down voltage (BDV), it does not necessarily mean it has caused the breakdown. At high voltage ratings, excessive moisture content in the oil may result an internal flashover between the live parts and earth, which all leave corresponding tell tale marks.
What is failure due to lightning discharge?
1. Failure due to Lightning Discharge or Overvoltages. This is characterized by break down of the end turns close to the line terminal. There may be a break in the turns or end lead, and also flash marks on the end coil and earthed parts close to it, but the rest of the coils will be found to be healthy. 2.
Is a transformer failure a sudden phenomenon?
Failure of transformer in power substation is not a sudden phenomenon, for that matter each and every failure will take place only after alerting through some pre-signs. If they went unnoticed or unattended will results into a failure.
Why is my transformer failing?
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 often causes a physical deforming of the transformer or the area surrounding it.
What happens if the transformer's input voltage does not climb to the expected value?
If the input power climbs to the expected value, the primary of the transformer is bad. If the input power does not climb to the expected value, then the problem lies not with the transformer, but with the input circuitry.
What to do if there is no filtering or shaping?
If there is no filtering or shaping being performed by the secondary circuitry, use 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 not present on the secondary, either the transformer or a filtering or shaping component is bad.
What does it mean when a transformer is above the amperage rating?
If the reading is above the amperage rating for the transformer, the circuit is drawing too much power. Many common transformers have 3 amp fuses. The amperage rating for your transformer fuse may be labeled on the transformer, but will also be available in the circuit schematic. ...
What is the purpose of attaching capacitors to transformers?
It is common to attach capacitors and diodes to the transformer secondary to convert the AC power from the output to DC power. This information will not be available on the transformer label. Generally, you can find the transformer conversion and output filtering information on the schematic.
How many inputs and outputs are needed for a linear fuses?
For linear fuses, you'll only have one input and output. In this case, 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 by one to determine what component of the entire circuit is causing the short.
What is a transformer?
This article has been viewed 536,605 times. Transformers are an electrical component that transmit electrical energy between at least two circuits. Transformers regulate the voltage in circuits, but in some cases these can go bad and cause a circuit to not work.
What happens if your HVAC contactor is bad?
When there is a bad contactor, the entire unit is placed under a great deal of stress. Once the strain or tension becomes too high for the HVAC unit to hand, this will usually result in a blown transformer.
How many ohms does a transformer read?
A faulty transformer provides a wide-open or infinite reading, and a transformer that is not faulty will read from zero up to 10 ohms that indicate a closed circuit.
What is a transformer?
A transformer is a type of passive device that transfers electric energy between circuits. Electromagnetic induction is the process that accomplishes this.
What is a transformer transfer?
Transfers are utilized whenever the incoming electricity voltage must be lowered or raised to meet the requirements of certain electrical parts or components. A transformer’s job is to alter the energy traveling to the HVAC unit from the circuit board. That progression enables the fan and air conditioner to work synergistically while it is cycling ...
What causes a transformer to fail?
2. Wiring Issues – Loose wires or cables inside the transformer can cause a short circuit due to which the transformer may fry. 3. Power Surge – An electrical failure in the form of a power surge can also cause transformer failure.
What is the difference between a transformer and a transformer without fault?
For this, you need a multimeter, as well as the basic knowledge of using it. A faulty transformer gives an infinite or wide-open reading while a transformer without any fault reads between zero to 10 ohms which is indicative of a closed circuit.
How does a transformer work?
The work of a transformer is to change the voltage that travels from the circuit board to the HVAC unit. This progression allows the air conditioner and the fan to work in synergy while cycling on and off. The usage of Electricity can be amplified or diminished depending on how much power is needed.
Why does my transformer make a humming noise?
1. Humming And Vibrating – The humming sound in transformers is normal. It is produced due to the expansion and contraction of the laminations or the iron core. However, if there is a drastic increase in this sound, accompanied by strong vibrations, it is indicative of a bad transformer in your HVAC unit.
Why is my HVAC not working?
HVAC Not Working – With a bad transformer, your HVAC unit will not work even when it has an adequate power supply. This is a protective mechanism to save the unit from severe damage. There is no sure-shot way of confirming that the HVAC unit is malfunctioning due to a fault in the transformer.
What is a transformer?
A transformer is a device which can increase or decrease the voltage of an alternating current or AC. It is a passive device which transfers electrical energy from one circuit to another. This is achieved through electromagnetic induction.
Where is the transformer located in an HVAC unit?
In an HVAC unit, the transformer is located inside the furnace. But in a few cases, which is less than 10%, it can be found inside the AC unit situated outside.
Where to check if transformer is in garage?
If your transformer isn't located near an exterior outlet or in the garage, check the shed in the back yard. If 110v power has been ran out to the shed, its likely the transformer could have been installed there.
What happens if an outlet doesn't have power?
If the outlet doesn't have power, the transformer won't have power either. To test your outlet, plug in an electrical device and see if it works. A mobile phone charger will be great for this. After you plug the charger into the outlet, plug the charging cord into your phone.
How to reset a GFCI breaker?
Go to your breaker panel and try to locate the flipped breaker switch. Look closely, sometimes a breaker switch won't flip all the way after its been tripped. Be sure to check all your breaker panels. If you are able to locate your tripped breaker switch and reset it, your GFCI should reset.
How to tell if a GFCI is shut off?
If your GFCI is shut off, try pressing in the reset button to see if it restores power.
How to read ohms on a transformer?
You should read zero ohms, or “continuity”, through the primary of the transformer. Next connect the ohmmeter between either line lead and the secondary of the transformer. You should read infinite ohms, or “no continuity”. Now connect the ohmmeter between either line lead and the ground (or frame) of the transformer.
How many amps should a 110V transformer draw?
If you have a clamp type ammeter, you can check the primary current draw of the 110V line. It should be no more than 1 to 2 amps for most transformers. If you have any questions, feel free to call T. J. Snow’s transformer experts at (423) 894-6234.
