What does it mean when a transformer is buzzing?
The magnetostrictive effect is one of the main causes of transformer noise. When a magnetic field is applied to ferromagnetic materials, their size changes. Power transformers have iron cores that are magnetically attracted to alternating current flowing through their coils. Creating a buzzing sound, it expands and contracts the core.
What causes a transformer to hum loudly？
There is a possibility that the transformer can hum due to the magnetostrictive effect of its core. It is due to a phenomenon called magnetostriction that transformers hum. During the process of magnetization, ferromagnetic materials undergo magnetostriction, which is the process by which their shape or size changes. In 1842, James Joule discovered this effect while observing a sample of iron. Frictional heating of the sensitive ferromagnetic core results in energy loss. An alternating current causes the core of the transformer to be magnetized in a time-varying manner. An alternating current causes the core of the transformer to be magnetized in a time-varying manner. The transformer hums as a result of this.
How to eliminate transformer hum？
Noise from transformers cannot be completely eliminated, but certain design considerations can help to reduce it to a great extent. In spite of the fact that magnetostriction cannot be completely eliminated, the design, assembly, and installation of transformers can control it to a certain extent while masking the noise to some extent.
Here are some precautions you can take during the installation and installation process so that the audible humming can be minimized:
1.Install in a low-traffic area
It is probable that one will find the transformer noise irritating if it is located in a heavily trafficked area, especially if the ambient noise is below the sound level of the transformer. Make sure that there is at least one low-traffic area between the transformer and high-traffic areas such as offices, homes, etc. on either side of the transformer.
2.Corners, stairwells, and hallways should be avoided
The transformer should be installed in a corner or at the top of the ceiling of the room.You should also avoid installing it in narrow hallways, halls, or staircases as well. As with corners in rooms, these areas will accumulate sound and reflect it back to louder areas.
3.Place the unit on a solid surface
In order to reduce transformer noise, equipment should be installed on dense, heavy surfaces, such as reinforced concrete or floors, rather than thin curtain walls or plywood surfaces. It is recommended that the mounting surface should weigh 10 times as much as the unit itself for best results.
4.Make sure that the housing bolts are tight
Make sure that the bolts and screws on the transformer cover and top are secure. During operation of the transformer, the loose parts vibrate and contribute to the existing sound. You should also remove any eyebolts used during installation to avoid adding noise.
5.Using acoustic dampening materials
Power transformers can be made quieter by using materials that block sound transmission. Using sound absorbing materials, such as sulphur, soundproofing tiles or fiberglass, can reduce noise in transformer rooms.
6.Vibration dampers should be installed
To ensure that the transformer operates safely and reliably at all times, it is recommended that a composite shock absorber is installed on the transformer’s base as a means of effectively eliminating vibration and noise.
7.Processing of soft connections
In order to deal with the transmission path of vibrations and noise, a soft connection is made between the busbar copper rack and the rigidly installed busbar copper rack.
8.Oil barriers or bumpers should be used
Transformer noise can also be reduced by using sound dampening materials, oil barriers, and cushioning pads. In addition to reducing the sound and vibration, they also help reduce the irritation caused to people in the immediate vicinity as a result of the noise or vibration.
9.Consider flexible installation techniques
When installing power transformers on structural walls, columns, ceilings, or frames, it is recommended that external shock absorbers be used as well as flexible connection and installation methods. Consequently, there will be no metal contact between the mounting surface and the unit, which will reduce noise transmission.
10.Follow the instructions provided by the manufacturer
Be sure to follow the manufacturer’s instructions and guidelines when using the product.
As well as reducing transformer noise, the following other methods can also be used:
1.Vibration source noise should be reduced
- High-quality silicon steel sheet with low magnetostriction and high magnetic permeability.\
- Improve and reduce the core seams by adopting an excellent core structure. To reduce noise, the iron core uses multi-stage seams to increase damping. In order to increase the damping effect and reduce the noise of the iron core, a thin layer of oil-resistant rubber is added between the pieces of iron core at a certain thickness.
2.Vibrations are reduced and sound energy is absorbed
- Magnetic core noise is transmitted through the bottom of the box and the foundation. By adding a buffer between the body and the tank or between the tank and the foundation, the sound can be attenuated. As vibration is transmitted from the iron core and the magnetic shield to the fuel tank, rubber anti-vibration pads can be placed at the iron core feet and between the magnetic shield and the box wall, so that the rigid connection becomes elastic, thus reducing vibration, preventing resonance, and reducing noise.
- By putting sound insulation material inside the reinforced iron of the fuel tank, the energy of the vibration of the fuel tank can be absorbed, and the body noise can be reduced.
3.Reduce noise by adding a sound insulation layer
- The sound insulation board can be made into several pieces, and the sound-absorbing material can be placed in the steel plate depending on the external structure of the fuel tank.Materials that absorb sound include rock wool, glass fiber, etc. Part of the noise emitted by the transformer body can be reflected back by the soundproof wall; The sound insulation wall can also absorb noise, and some of it can also reduce noise when it passes through. With the use of single-piece sound-insulating panels, the reinforcing iron of the fuel tank can be effectively insulated from noise.
- It is possible to soundproof equipment. Transformer noise propagates in all directions, so sound insulation should be installed around it. Using a sound insulation cover or semi-sound insulation cover can reduce noise and attenuate sound energy.
4.Make the cooling unit less noisy
- Instead of using air conditioners, use natural cooling. Self-cooling should be used whenever possible when designing low no-load noise transformers, as it can eliminate noise from fans and oil pumps.
- To meet the heat dissipation needs of a large-capacity transformer, choose a low-noise submersible pump and a cooler with a low-speed fan when the transformer capacity is not sufficient.
In other words, because the transformer noise is generated in multiple ways, the control transformer noise should also be comprehensively considered in terms of the noise generated by the body, the noise generated by the cooling device, and the propagation path in order to achieve a satisfactory noise reduction.
How does transformer age affect noise levels?
It is possible for noise to increase with age, and the adhesive holding the core layer can break down over time, leading to an increase in noise. Transformer noise can also be caused by electromechanical forces in the windings of transformers and in the cooling systems of transformers, in addition to magnetostriction.
