CN204204602U - A kind of low-noise level transformer - Google Patents

Abstract

The utility model relates to a low-noise transformer, which comprises an iron core, a low-voltage coil, a high-voltage coil, a shell, and a perforated plate; the perforated plates are respectively located between the iron core and the low-voltage coil, between the low-voltage coil and the high-voltage coil, and between the high-voltage coil and the shell ; The perforated plate changes the acoustic resonance frequency of the transformer core and coil to avoid the frequency of electromagnetic noise and avoid the amplification of noise by acoustic resonance; the noise emitted. The low-noise transformer of the utility model can reduce the noise emitted by the transformer and is beneficial to protect the environment.

Description

A low noise transformer

technical field

The utility model relates to the technical field of power transformers, in particular to a noise-reducing transformer.

Background technique

During the operation and use of power transformers and reactors, the magnetostrictive effect of the magnetic conductive material will generate iron core noise, the alternating electromagnetic force on the coil will generate winding load noise, and the auxiliary cooling fan and oil pump device will generate fan oil pump operation noise. These noises will increase the environmental noise. For the control of operating noise of auxiliary devices, many transformers do not use fans and oil pumps in design; on the other hand, there are relatively mature control technologies for operating noise of auxiliary devices.

The frequency of transformer electromagnetic noise generated by magnetostriction and alternating electromagnetic force is the basic frequency of twice the power supply frequency and the multiplier frequency of the integer multiple of the basic frequency. For a transformer with a power supply frequency of 50Hz, the noise frequency is 100Hz, 200Hz, 300Hz, 400Hz , and 600Hz. Because transformer noise has the characteristics of low frequency, slow attenuation, and long-distance propagation, it is still difficult to eliminate or reduce the electromagnetic noise of transformers economically and effectively.

For transformers whose magnetic material is cold-rolled grain-oriented silicon steel sheet, one of the methods to reduce the noise of the transformer is to reduce the magnetic flux density of the iron core. Usually, the noise of the transformer can be reduced by about 2dB for every 0.1T reduction of the magnetic density, but this will increase by about 100%. Six material costs. For the amorphous alloy iron core, its magnetostriction rate is large, and the noise problem of the iron core of the transformer is more prominent. If sound-absorbing materials are used, such as glass wool felt or foam rubber, the sound-absorbing materials have poor absorption of low-frequency electromagnetic noise, and the noise reduction effect is not ideal; due to the large volume of sound-absorbing materials, it usually affects the ventilation and heat dissipation of the transformer.

Another cause of transformer noise is transformer core acoustic resonance, coil acoustic resonance, tank or casing acoustic resonance, or their combined acoustic resonance. From the perspective of transformer design, calculating the core acoustic resonance frequency, coil acoustic resonance frequency, oil tank casing acoustic resonance frequency, or structural combination acoustic resonance frequency, etc., avoiding the transformer electromagnetic noise frequency in the design is another measure to reduce noise. However, there are still two difficulties in this measure. One is that the acoustic resonance or resonance frequency of the transformer structure is difficult to calculate, and the other is that the acoustic resonance modes and orders of the transformer are many, which is difficult to avoid in the design.

In the field of noise control, Mr. Ma Dayou, a famous acoustician, proposed the sound-absorbing structure and theory of micro-perforated plates. The sound-absorbing structure of micro-perforated plates is shown in Figure 1. In Fig. 1, the thickness of the micro-perforated plate (1) is δ, and holes with diameter d are perforated, the distance between the holes is a and b, the distance between the micro-perforated plate (1) and the wall is L, and the sound wave (5) of sound pressure p passes through Through the micro-perforated plate (1), acoustic resonance is formed in the cavity between the micro-perforated plate (1) and the wall, and the micro-perforated plate (1) absorbs the energy of the sound wave (5). The cavity acoustic resonance frequency f ₀ is as follows:

f ₀ =c ₀ ·(q/δ/L) ^0.5 /2/π

In the formula, c ₀ is the speed of sound wave propagation, and q is the perforation area ratio. The micro-perforated plate sound-absorbing structure proposed by Mr. Ma Dayou has excellent low-frequency noise absorption characteristics when the aperture d is less than 1mm, and the cost is low. This micro-perforated plate sound absorption theory includes two aspects: adjusting the size of the aperture and perforation rate can adjust the cavity acoustic resonance frequency; reducing the aperture can absorb more noise energy.

The simplified structure of transformer and sound wave propagation are as Fig. 2, and transformer comprises iron core (2), the low-voltage coil (31) of coil (3) and high-voltage coil (32), and shell (4); Can not comprise shell (4) to dry-type transformer ). The noise of the transformer has two ways of solid transmission and fluid (gas or liquid) transmission in the transformer structure. The noise sound wave (5) shown in Figure 2 is according to the iron core (2)-low voltage coil (31)-high voltage coil (32) - The direction of the shell (4), the noise transmitted in the fluid medium, is the main component of the transformer noise. Avoiding the overlapping resonance between the acoustic resonance frequency of the transformer and the frequency of the noise sound wave (5), and absorbing the energy of the noise sound wave (5), all can reduce transformer noise.

Simplified structure of a transformer In Figure 2, the main insulating medium: air or transformer oil is not shown. The main insulating medium is air, that is, dry-type transformer; the main insulating medium is transformer oil, that is, oil-immersed transformer. Regardless of whether the main insulating medium is gas or liquid, the laws of noise transmission and absorption are the same.

Utility model content

The technical problem to be solved by the utility model is: to propose a low-noise transformer, which can reduce the electromagnetic noise generated during the operation of the power transformer.

The technical solution adopted in the utility model is: a low-noise transformer, including an iron core, a coil and a perforated plate, the perforated plate is located between the iron core and the coil, there is a cavity between the iron core and the perforated plate, and the perforated plate and the coil There is also a cavity between them; adjusting the perforated area ratio of the perforated plate can change the acoustic resonance frequency of the cavity; The acoustic resonant frequencies of the two cavities avoid noise frequencies to avoid noise amplification; the perforated plate absorbs part of the energy of the noise generated by the iron core and the coil to reduce the noise emitted by the transformer.

Further, the coil described in the utility model includes a low-voltage coil and a high-voltage coil, and a perforated plate is placed between the low-voltage coil and the high-voltage coil. There is a cavity between the low-voltage coil and the perforated plate; there is also a cavity between the perforated plate and the high-voltage coil. cavity; the acoustic resonance frequency of the two cavities avoids the frequency of the noise to avoid noise amplification; the perforated plate absorbs part of the energy of the noise transmitted through the coil to reduce the noise emitted by the transformer to the outside.

Furthermore, there is an insulating cylinder between the low-voltage coil and the high-voltage coil described in the present invention, the perforated plate is located between the low-voltage coil and the insulating cylinder, and another perforated plate is placed between the insulating cylinder and the high-voltage coil There are cavities between the two perforated plates and the low-voltage coil, between the insulating cylinder and the high-voltage coil; the acoustic resonance frequency of the cavity avoids the frequency of noise, and avoids noise amplification; the perforated plate Absorb part of the energy of the noise transmitted through the coil, and reduce the noise emitted by the transformer to the outside.

Furthermore, the transformer described in the utility model has a casing, a perforated plate is provided between the coil and the casing, a cavity is provided between the coil and the perforated plate, and a cavity with two ends is closed between the perforated plate and the casing. The closed cavity at both ends between the perforated plate and the shell is a sound-absorbing resonant cavity, the acoustic resonance frequency of the sound-absorbing resonant cavity is the same as the frequency of the noise, and the sound-absorbing perforated plate absorbs the energy of the noise transmitted from the coil to the shell , to reduce the noise emitted by the transformer to the outside.

Furthermore, there is a perforated plate between the shell and the iron core described in the utility model, there is a cavity between the iron core and the perforated plate, and there is a cavity with two ends closed between the perforated plate and the shell. The closed cavity at both ends between the shells is a sound-absorbing resonant cavity. The acoustic resonance frequency of the sound-absorbing resonant cavity is the same as the frequency of the noise. The sound-absorbing perforated plate absorbs the energy of the noise transmitted from the core to the shell, reducing the external emission of the transformer. noise.

When the main insulating medium of the transformer described in the utility model is air, the transformer is a dry-type transformer; when the main insulating medium of the transformer is transformer oil, the transformer is an oil-immersed transformer. The acoustic wave transmission medium in the cavity formed by the perforated plate and the parts of the transformer in the utility model is the fluid.

The perforated plate described in the utility model is a micro-perforated film, and the micro-perforated film plays the role of adjusting the acoustic resonance frequency of the transformer and absorbing noise energy.

The beneficial effects of the utility model are: on the premise of not changing the original structure and size of the transformer, the perforated plate is used to effectively reduce the low-frequency noise of the transformer, protect the environment, and reduce the material cost of the transformer.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Figure 1 is a sound-absorbing structural diagram of a perforated plate;

Fig. 2 is a simplified structure and sound wave propagation diagram of a transformer;

Fig. 3 is a simplified structure of the transformer of the present invention and a schematic diagram of the placement of perforated plates;

Fig. 4 is the perforated circular cylinder of the utility model transformer;

Fig. 5 is the A-A sectional plan view of Fig. 3;

Fig. 6 is the simplified structure of the utility model transformer and the second schematic diagram of the placement of the perforated plate;

Fig. 7 is the B-B sectional plan view of Fig. 6;

Fig. 8 is the simplified structure of the transformer of the present invention and the third schematic diagram of the placement of the perforated plate.

Detailed ways

Now in conjunction with accompanying drawing and preferred embodiment the utility model is described in further detail. These drawings are all simplified schematic diagrams, and only schematically illustrate the basic structure of the utility model, so they only show the configurations related to the utility model.

The low-noise transformer of the present utility model, as shown in Figure 3, is a 1250kVA three-phase epoxy resin casting dry-type transformer, and the perforated circle shown in Figure 4 is placed between the stepped circular iron core 2 and the circular low-voltage coil 31. Shaped cylinder 121, one for each phase, three in total; circular cylinder 121 is a polyester sheet with a thickness of 0.5 mm, the diameter of the plate perforation is 0.5 mm, and the hole spacing is 20 mm (a) and 20 mm (b);

The circular cylinder perforated plate 121 is spaced 6 mm from the iron core 2 and 6 mm from the low-voltage coil 31 . Between the low-voltage coil 31 and the high-voltage coil 32, a perforated circular cylinder 131 is placed, one for each phase, three in total; the circular cylinder 131 is a polyester sheet with a thickness of 1.1 mm, the diameter of the plate perforation is 0.5 mm, and the hole spacing is 10 mm ( a) and 10mm (b); the distance between the circular cylinder 131 and the low-voltage coil 31 is 17mm, and the distance between the cylinder 131 and the high-voltage coil is 17mm. Fig. 5 is a top view of section A─A of Fig. 3 . The selected perforation diameter and related dimensions make the resonant frequency f0 of the cavity formed by the perforated plate avoid the original noise frequency of 300Hz. The sound pressure level noise of the transformer with perforated cylinders 121 and 131 is about 5dB(A) lower than that of the original transformer without perforated cylinders, and mainly reduces the low-frequency noise at 300 Hz.

What Fig. 6 shows is another embodiment of the utility model, transformer has shell 4, has perforated plate 141 between coil 3 and shell 4, has cavity between coil 3 and perforated plate 141, perforated plate 141 and There are cavities closed at both ends between the shells 4, and the closed cavities at both ends between the perforated plate 141 and the shell 4 are sound-absorbing resonant cavities. The acoustic resonance frequency of the sound-absorbing resonant cavity is the same as the frequency of the noise 5. The acoustic perforated plate 141 absorbs the energy of the noise 5 transmitted from the coil 3 to the casing 4, reducing the noise emitted by the transformer to the outside. Fig. 7 is a top view of section B─B in Fig. 6 .

Another embodiment of the utility model shown in Fig. 8 has an insulating cylinder 33 between the low-voltage coil 31 and the high-voltage coil 32, the perforated plate 131 is located between the low-voltage coil 31 and the insulating cylinder 33, and between the insulating cylinder 33 and the high-voltage coil 32 placed perforated plate 132; perforated plates 131 and 132, between the low-voltage coil 31, between the insulating cylinder 33, and the high-voltage coil 32, there are cavities; multi-cavity acoustic resonance frequency avoids noise 5 frequency to avoid noise amplification; the perforated plates 131 and 132 absorb part of the energy of the noise 5 transmitted through the coil 3 to reduce the noise emitted by the transformer.

What is described in the above specification is only the specific implementation of the present utility model, and various illustrations do not limit the essential content of the present utility model. Those of ordinary skill in the art can make specific implementations described before after reading the specification. modification or deformation without departing from the essence and scope of the utility model.

Claims (8)

1. a low-noise level transformer, comprise iron core (2), coil (3) and perforated plate (121), it is characterized in that: described perforated plate (121) is positioned between iron core (2) and coil (3), there is cavity between (2) unshakable in one's determination and perforated plate (121), between perforated plate (121) and coil (3), also have cavity; Two described cavity acoustic resonance frequencies avoid the frequency of noise (5), avoid noise to amplify; Described perforated plate (121) absorbs the portion of energy of (2) unshakable in one's determination and coil (3) generation noise (5), reduces the noise that transformer externally sends.

2. a kind of low-noise level transformer as claimed in claim 1, it is characterized in that: described coil (3) comprises low-voltage coil (31) and high-tension coil (32), between low-voltage coil (31) and high-tension coil (32), place perforated plate (131), between low-voltage coil (31) and perforated plate (131), have cavity; Also cavity is had between perforated plate (131) and high-tension coil (32); Two described cavity acoustic resonance frequencies avoid the frequency of noise (5), avoid noise to amplify; Perforated plate (131) absorbs the portion of energy through coil (3) transmitted noise (5), reduces the noise that transformer externally sends.

3. a kind of low-noise level transformer as claimed in claim 2, it is characterized in that: with insulating cylinder (33) between described low-voltage coil (31) and high-tension coil (32), described perforated plate (131) is positioned between low-voltage coil (31) and insulating cylinder (33), places another perforated plate (132) between insulating cylinder (33) and high-tension coil (32); Between two described perforated plates and low-voltage coil (31), and insulating cylinder (33) between, and high-tension coil (32) between all have cavity; Described cavity acoustic resonance frequency avoids the frequency of noise (5), avoids noise to amplify; Perforated plate (131) and (132) absorb the portion of energy of the noise (5) transmitted through coil (3), reduce the noise that transformer externally sends.

4. a kind of low-noise level transformer as claimed in claim 1, it is characterized in that: described transformer is with shell (4), with perforated plate (141) between coil (3) and shell (4), cavity is had between coil (3) and perforated plate (141), the cavity of closed at both ends is had between perforated plate (141) and shell (4), closed at both ends cavity between described perforated plate (141) and shell (4) is for absorbing sound resonating cativty, the acoustic resonance frequency of sound absorption resonating cativty is identical with the frequency of noise (5), the perforated plate (141) of sound absorption absorbs by the energy of coil (3) to shell (4) transmitted noise (5), reduce the noise that transformer externally sends.

5. a kind of low-noise level transformer as claimed in claim 4, it is characterized in that: with perforated plate (122) between described shell (4) and (2) unshakable in one's determination, cavity is had between (2) unshakable in one's determination and perforated plate (122), the cavity of closed at both ends is had between perforated plate (122) and shell (4), closed at both ends cavity between described perforated plate (122) and shell (4) is for absorbing sound resonating cativty, the acoustic resonance frequency of sound absorption resonating cativty is identical with the frequency of noise (5), the perforated plate (122) of sound absorption absorbs by (2) the unshakable in one's determination energy to shell (4) transmitted noise (5), reduce the noise that transformer externally sends.

6. a kind of low-noise level transformer as claimed in claim 1, is characterized in that: the main insulation medium of described transformer is air, and described transformer is dry-type transformer.

7. a kind of low-noise level transformer as claimed in claim 1, is characterized in that: the main insulation medium of described transformer is transformer oil, and described transformer is oil-filled transformer.

8. a kind of low-noise level transformer as claimed in claim 1, is characterized in that: described perforated plate (121) is micropunch film.