Transformers are very important parts of electricity. A light buzzing or humming sound from the transformers is fine. But what if the sound is loud and buzzes constantly? Is that a normal thing or a sign of danger?
Generally, a buzzing transformer is not dangerous as it happens due to a natural phenomenon called magnetostriction. The magnitude depends on the load and harmonic contents. However, if the buzzing sound is very loud and continuous, you need to get an electrician.
There are multiple reasons behind a buzzing transformer. Some of them are natural, and some are dangerous and require fixation. This article will explain the reasons behind a buzzing transformer and how to reduce it.
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Is a buzzing transformer dangerous?
Usually, a buzzing sound from the transformer is not considered dangerous.
The buzzing and humming sometimes depend on the load, the load change, and the harmonic contents of the load.
The noise mainly occurs due to the vibration between the core material and the windings.
The noise generally remains around 2*f, i.e., 100-120 Hz.
But, the volume can increase depending on the load features.
The buzzing in the transformers will be only dangerous if the sound is clear and loud from a distance.
In that case, you must call an electrician to identify and fix the problem soon.
Why do the transformers have a buzzing sound?
It is normal for transformers to have a slight buzzing sound.
The problem occurs when the buzzing sound increases.
Here are some natural and unsafe reasons behind a buzzing transformer:
A transformer will make a buzzing noise due to the Magnetostriction effect.
In this method, the magnetic sheet piece of the transformer gets magnetized and extends itself.
When the magnetization is taken back, the sheet returns to its position.
A transformer gets magnetically excited due to the alternating voltage and the current.
Due to this excitement, the transformer extends and contracts twice during the full cycle of magnetization.
The core of the transformer is made up of many special steel metals in a way where it can reduce losses and heating effects.
If the contractions and expansions occur erratically, the transformer gets overwhelmed and creates vibrations and buzzing noises.
This kind of noise from the transformer is safe, and there is no danger here.
Depending on the load, the buzzing sound will increase.
Once the load increases in the transformer, so will the buzzing volume.
It is due to the mechanical forces between the individual conductors in the winding.
The transformer gets overwhelmed due to overloading.
The force creates a vibration and a buzzing noise, but only in one pure tone.
The volume will be twice the exciting frequency of 100 cps.
However, it gets swamped by the harmonics produced by the core.
If it is the load, you need to detect the transformer load.
In this case, the noise can be dangerous.
So, you must reduce the load or call a professional to deal with it.
Core lamination vibration
Sometimes, the buzzing sound is due to the core lamination vibration.
When the transformers are assembled, they are dipped into an electrical varnish.
It helps in protecting the winding of the transformers and seals the thin metal sheets of the core laminates.
In the beginning, you cannot hear the noise because the varnish will still seal the laminate sheets.
After some time, you will hear the buzzing sound, which sounds like some laminations have broken the varnish bond, and it buzzes at 60Hz.
If you are fine with the buzzing sound, your transformer is completely fine, and the sound is not dangerous for the unit.
But if the sound is too loud and the transformer is overheating, you need to contact the OEM to replace the transformer.
Other reasons behind the buzzing noise and vibration in the transformer
Other reasons behind the buzzing sound in the transformer could be the following:
- Under the magnetic flux’s influence, the coil’s winding becomes loose. As a result, the windings get shifted at the core, causing vibrations and buzzing sounds. You will need to tighten the coil and rewind the winding.
- If the fittings of the core plates are not up to the mark, it creates a gap between the plates. As a result, it causes vibrations and buzzing sounds in the transformer. Check for the core plates and fix them properly. If you cannot do it, hire a professional.
- Violating the integrity of the wires in the winding can create sparks and claps. Loud buzzing sounds will come out with powerful discharges.
- A loose transformer can also create vibration and buzzing noises. So, make sure your transformer is tight enough.
What should be the sound level (dBA) of the transformers?
|Constant voltage transformer
You can try Acoustic Echo Barriers to reduce the noise level in your surrounding area, even during hard climates.
They can reduce the sound to around 43dB.
What can I do to stop or lower the buzzing sound?
It is impossible to stop the transformer’s buzzing caused by magnetostriction or core lamination.
But, for other reasons, like overloading, loose transformer or coil, or disassembled core plates, you need to reduce the load, tighten the transformer and the coil, and properly fix the plates.
Since it is an electrical matter, you might need an electrician’s help to fix everything perfectly.
To prevent the buzzing of the transformer, you can try the following methods during installation:
Select a low-traffic site for installation
If the transformer is located in a place full of traffic, the transformers will create a loud buzzing noise.
There has to be at least one low-traffic room between each transformer and high-traffic areas in the offices and commercial or residential buildings.
Maintain at least 10-foot clearance on all sides of the transformer except for the ground.
Avoid corners, stairwells, and corridors.
Corners, stairwells, corridors, or areas close to the ceilings can amplify the noise of the transformers.
They already have buzzing noises naturally.
On top of that, if they are too close to such areas, the noise will be loud and irritating.
The noise may trigger your mind about some danger.
You should hire a professional to find the real cause if you suspect such things.
The corners and corridors double the sound of the transformer buzzing and reflect much louder than normal.
Mound the unit of a solid surface
Thin curtains or plywood areas can increase the buzzing noise of the transformer.
You might get alarmed by this, but there might not be anything to worry about here.
You only need to mount the units over a dense, heavy, solid surface, such as concrete walls or floors.
You can put the transformers over surfaces that weigh 10 times the unit for the best results.
Tighten the bolts on enclosures
Ensure that the bolts and screws on the top and cover of the transformer are properly tightened.
If those parts are loose, the transformer will vibrate whenever it runs, and the buzzing sound will increase.
Lifted eyebolts can also create noises in the transformer. So, remove them from the transformer after installation.
Use acoustic-dampening materials
You can reduce the amount of buzzing noise in the transformer by using materials that can help prevent the buzzing.
Cover the walls of the transformer with absorbents like kimsul, acoustical tile, or fiberglass.
These materials can help in reducing the transformer buzzing.
Use oil barriers or cushion padding.
Like the acoustic dampening materials, the oil barriers and cushion padding can also help reduce and insulate the transformer’s buzzing sound.
You cannot cut down the sound of the vibrations, but you can decrease the irritation caused due to the noise and vibration from your surroundings.
Use flexible mounting techniques.
You can use external vibration dampeners with flexible connections and mounting methods when installing transformers in the walls, columns, ceilings, or frames.
It will prevent the buzzing sound from increasing to a great extent.
Flexible mounting techniques help prevent the metal contact between the surface and the unit, thus preventing noise.
Try innovative techniques and materials.
Try the recent technologies, designs, materials, and installation methods while exploring the transformers.
The extra effort will be worth it and keep your transformer safe in the long run.
Today, you can create transformer tanks with materials that can help minimize the buzzing noise of the transformer.
So, try looking for the latest and modern solutions before deciding anything.
Surround the transformer with Echo Barriers
Try keeping portable acoustic Echo Barriers around your transformers to reduce the sound nearly up to 43dB.
These barriers will even work in harsh weather and working conditions.
Follow the instructor’s guidelines.
Last, but not least, you should follow the manufacturers’ and instructors’ guidelines.
Suppose the design has vibration dampeners between the core, case, and coil assembly mounting.
In that case, the manufacturers recommend removing the bolts after installing the transformers.
Attenuation and baffling
This method is another way of reducing the noise of the transformer.
Generally, the buzzing noise from the transformer is not dangerous, especially in the case of magnetostriction and core laminations.
The best way to decrease the noise of a transformer is to place it miles away from your habitation.
- Put the transformer in a place where the walls and floors are big enough to lower the volume of the transformer to the person listening on the other side. The noise will reduce by attenuation every time it passes through the walls. Walls can be made of bricks, steel, concrete, lead, etc.
- Put the transformer inside an enclosure that uses a limp wall procedure. This process involves using two thin plates individually with a rubber material. The noise hits the inner sheet, and the energy gets used inside that rubber material. As a result, the outer sheet doesn’t vibrate and doesn’t make any noise.
- Building a screen wall around the wall will also reduce the noise of the transformer, especially those near the wall. However, the noise gets over the screen wall and falls somewhere else at the lower level. The screens can be of concrete, wood, brick, dense bushes, etc.
- Avoid creating reflecting surfaces with the half wavelength of the frequency. If the noise hits the reflecting surface, the noise will be loud and create echoes. So, you need absorbent materials for offending walls, like fiberglass, wool, etc.
- Remove the coils and core of the transformer from the ground.
- Use materials to terminate the transformer frequencies at 100 cps upwards.
- The connections to the solid reflecting surfaces have to be flexible. The connections include the incoming cables, bus bars, stand-off insulators, and others. A solid connection to a solid structure will cause vibration.
- You should remove the shipping bolts and anti-vibration pads to prevent short circuits and noises.
Why does the fan make a noise?
The fans of the transformers are used to remove the heat from the transformer and avoid overheating.
The more fans your transformer has, the more noise the unit will make.
It is natural, and you do not have anything to do here.
Other factors that can affect the noise of the transformer are:
- Tip speed
- Blade design
- Radiator arrangements
Transformers making noises are natural in most cases due to the magnetostriction.
The magnetism in the transformer gets excited due to the current and voltage and starts expanding and contracting. It is quite natural and occurs twice a day.
Other than that, it could be due to core lamination or overloading. Reduce the load to decrease the sound level and vibrations.
Noise can also result from loose transformers, irregularly arranged core plates, or loose coils. You must tighten the transformer and the coil and arrange the plates properly.
If the sound is too much to handle, hire a professional to find the real cause and fix it.
You can try several methods to suppress the noise, like using acoustic dampening materials, oil barriers, cushion padding, flexible mounting techniques, mounting on solid surfaces, and many more.
Sometimes, the noise is due to the fans. The fans help the transformer lose the hot air. The more fans you have, the more noise you hear.
Reference: TRANSFORMER NOISE AND STRAY MAGNETIC FIELDS, Effect of transformer noise.