CN201011632Y - Transformer with heat protecting equipment - Google Patents
Transformer with heat protecting equipment Download PDFInfo
- Publication number
- CN201011632Y CN201011632Y CNU2007200009529U CN200720000952U CN201011632Y CN 201011632 Y CN201011632 Y CN 201011632Y CN U2007200009529 U CNU2007200009529 U CN U2007200009529U CN 200720000952 U CN200720000952 U CN 200720000952U CN 201011632 Y CN201011632 Y CN 201011632Y
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- Prior art keywords
- transformer
- thermal
- winding
- mounting box
- thermal fuse
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- Expired - Fee Related
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- 238000004804 winding Methods 0.000 claims abstract description 86
- 229910045601 alloy Inorganic materials 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 239000007769 metal material Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 239000004020 conductor Substances 0.000 claims 1
- 230000001012 protector Effects 0.000 claims 1
- 238000013021 overheating Methods 0.000 abstract description 6
- 238000010438 heat treatment Methods 0.000 abstract 7
- 238000009413 insulation Methods 0.000 description 9
- 230000032683 aging Effects 0.000 description 6
- 238000009434 installation Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910000743 fusible alloy Inorganic materials 0.000 description 4
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Regulation Of General Use Transformers (AREA)
- Housings And Mounting Of Transformers (AREA)
Abstract
The utility model discloses a transformer with a heating protecting device. The utility model comprises a loop winding and a heating protecting device; wherein the heating protecting device is connected in series in the primary winding; an installing box for the heating protecting device is arranged between the secondary windings; and the heating protecting device can be arranged in the installing box and contacts with each secondary windings. The utility model has a small volume, is convenient to be made and has a low cost; the utility model can provide a reliable heating protection for the mini transformer; the utility model enhances the service life of the mini transformer; moreover the utility model can be used continuously after changing a new heating fuse plug when the transformer has over heating phenomena; and the utility model can effectively reduce the maintaining cost of the device.
Description
Technical Field
The utility model relates to a transformer with thermal protection device.
Background
The life expectancy of a transformer is determined by the aging rate of its insulating medium. During operation of the transformer, the winding coil heats up due to resistive losses, raising the temperature of its windings themselves, a phenomenon that accelerates the ageing of the transformer insulation. For the transformer using the A-level insulating material, the insulation aging speed is doubled when the temperature is increased by 6 ℃, and the service life of the transformer is reduced by half. When the winding temperature exceeds the maximum temperature allowed by its insulation, the insulation will be damaged by overheating, directly resulting in damage to the transformer. Therefore, it is important to protect the transformer from overheating by using a protection device for limiting the temperature of the winding.
The small transformer is limited by the factors of volume, weight and the like, so that the complicated temperature protection and test method commonly used by large and medium transformers cannot be adopted, and the small transformer generally adopts protection devices such as a fuse, an overcurrent releaser, a thermal circuit breaker and the like for overheat protection. The principle of overheat protection of fuses and overcurrent releases is to limit the winding current to prevent the winding temperature from being too high, and for small transformers using such current-limiting overheat protection devices, if the current limit value is chosen too low, the overload capability of the transformer will not be satisfactory, and if the current limit value is chosen too high, the overheat protection effect will not be good in case of overload.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that to the above-mentioned deficiency that prior art exists, provide a transformer that small, installation simple and convenient, can implement overheat protection to the transformer reliably.
The transformer with the thermal protection device comprises coil windings and the thermal protection device, wherein the thermal protection device is connected in series in the primary winding, a mounting box for mounting the thermal protection device is arranged between the secondary windings, and the thermal protection device can be mounted in the mounting box and can be in contact with the secondary windings.
The utility model provides a transformer overheat protection scheme based on thermal protection device has great practical value. The overheat damage mechanism of the transformer is that when the temperature exceeds the allowable value, the insulation layer between the coils is damaged due to the excessive temperature, so that sparking occurs between the coils, and finally the insulation layer is permanently damaged. The most straightforward thermal protection scheme for transformers is therefore to ensure that the temperature of the transformer coils or cores is maintained within the permitted range by monitoring the temperature thereof. The temperature distribution over the coil is not uniform due to the coil structure and the properties of the insulation itself, so that the insulation aging rate will depend on the temperature of the hottest spot on the winding.
The utility model discloses an experimental mode has carried out the analysis because of the overheated distribution that transships and short circuit lead to the transformer. During the experiment, the thermal protection device is arranged between the transformer windings firstly to ensure that the transformer is not damaged in the experiment process and the finish time of the experiment is determined, the overload and short-circuit are carried out, the overload or short-circuit experiment is respectively carried out on one secondary winding, the rated load is added to the rest windings, the resistance value of each winding is measured immediately after the thermal protection device acts, and the actual temperature of the winding is determined according to the following formula:
in the formula: delta t-temperature rise, deg.C;
R 1 -the resistance value of the winding at the start of the test, Ω;
R 2 -the resistance value of the winding at the end of the test, Ω;
t 1 room temperature at the start of the test, ° c;
t 2 room temperature, deg.C at the end of the test.
Experimental results show that for small transformers, if the transformer is in an overload or short circuit condition, the temperature of the corresponding short or overload secondary winding is highest. Therefore, the whole transformer can be comprehensively thermally protected only by ensuring that each secondary winding is under the protection of the thermal protection device. To ensure the reliability of the thermal protection scheme of the transformer, the above experiment can be performed to determine the installation position of the thermal protection device for different types of transformers.
According to the numerical calculation and experimental results (refer to the study on the temperature rise of the hottest point of the wound dry type transformer and the insulation aging of the wound dry type transformer, black dragon river electric power 2000, 22 (5): 8-10.) of the students about the temperature field of the winding of the transformer, the highest temperature point of each winding of the transformer appears at the longitudinal center of the secondary winding, therefore, the position of the thermal protection device in the installation box is the longitudinal center of the secondary winding, and the thermal protection device can sense the highest temperature point of the winding because the two side surfaces of the thermal protection device in the installation box are in full contact with the installation box.
The mounting box can be made of a material with good heat conductivity, preferably, the material with good heat conductivity used for the mounting box is a metal material, and further preferably, the metal material used for the mounting box is a thin copper sheet, and the cross section of the thin copper sheet is matched with the shape of the thermal protection device.
The thermal protection device adopts a thermal fuse, and the mounting box is rectangular and has a size which is matched with the sectional size of the thermal fuse. The temperature of a winding coil and an iron core of the transformer is monitored by the thermal fuse through serially connecting the thermal fuse into a primary winding of the transformer. When the temperature exceeds the action temperature of the thermal fuse (devices with different action temperatures can be selected), the thermal fuse acts (blows) and cuts off the current in the primary winding of the transformer, so that the temperature of the winding and the iron core of the transformer is ensured not to exceed the allowable range.
The thermal fuse can be an alloy type thermal fuse (thermal fuse), the thermal fuse senses the ambient temperature when in use, when the temperature reaches the melting point of the fusible alloy, the fusible alloy is melted, and the melted alloy is quickly shrunk into balls under the action of special resin, so that the current in the primary winding coil is cut off. The temperature fuse has the characteristics of small volume, low price and high reliability, and the rated current range of the temperature fuse is 1-25A under the normal temperature range.
The utility model discloses in, the mounting box can be provided with a plurality ofly, and its quantity can be decided according to the actual conditions of transformer winding, and it sets up the principle and must guarantee when arbitrary winding takes place the short circuit or transship, all has a thermal fuse to contact with transformer secondary winding's the highest temperature point.
The utility model discloses small in size, preparation convenience, low cost can provide reliable thermal protection for small-size transformer, have improved the life of transformer effectively. And after a new thermal fuse is replaced, the transformer can be continuously used after an overheating condition occurs, so that the maintenance cost of the equipment is effectively reduced.
Drawings
FIG. 1 is a transverse cross-sectional view of a transformer winding according to embodiment 1 of the present invention
FIG. 2 is a plan view of a transformer winding in embodiment 1, showing a position where a thermal fuse is mounted in a mounting box
FIG. 3 is a schematic circuit diagram of the transformer winding wiring in embodiment 1
Fig. 4 is a transverse cross-sectional view of a transformer winding provided with a plurality of mounting boxes in embodiment 2 of the present invention
In the figure: 1-annular transformer iron core 2-primary winding 3-first secondary winding 4-second secondary winding 5-first mounting box 6-first thermal fuse 7-second mounting box 8-second thermal fuse 9-transformer winding outline 10-annular transformer 11-third secondary winding 12-third mounting box 13-third thermal fuse 14-fourth mounting box 15-fourth thermal fuse
Detailed Description
The present invention will be described in further detail with reference to the following embodiments and accompanying drawings.
The following examples are non-limiting examples of the present invention.
Example 1:
in the present embodiment, a toroidal transformer is used as the transformer. If the major axis direction of the ellipse of the toroidal transformer core is defined as the longitudinal direction and the minor axis direction is defined as the transverse direction, fig. 1 and 4 are both transverse cross-sectional views of the transformer winding.
As shown in fig. 1 and 2, since the toroidal transformer is used, the cross section of the winding is bilaterally symmetric. The annular transformer iron core 1 is wound with a primary winding 2, a first secondary winding 3 and a second secondary winding 4 in sequence. For the two sides of the ring-shaped transformer core 1 which are symmetrical left and right, a first mounting box 5 and a second mounting box 7 are respectively arranged between the first secondary winding 3 and the second secondary winding 4, the two side surfaces of the first mounting box 5 and the second mounting box 7 are respectively in reliable contact with the first secondary winding 3 and the second secondary winding 4, and the two mounting boxes are symmetrical in position. The mounting box is internally provided with a thermal protection device.
In this embodiment, the thermal protection device of the transformer uses a thermal fuse, and the thermal fuse is an alloy type thermal fuse, and its rated current range is 1 to 25A in the normal temperature range. As shown in fig. 3, there are two thermal fuses, i.e., a first thermal fuse 6 and a second thermal fuse 8, which are respectively connected in series in the primary winding of the ring transformer 10. As shown in fig. 1 and 2, the first thermal fuse 6 and the second thermal fuse 8 are respectively disposed in the first mounting case 5 and the second mounting case 7.
The first and second mounting boxes 5 and 7 are made of thin copper sheets having a sectional shape of a rectangle adapted to the sectional shapes of the first and second thermal fuses 6 and 8 so that the thermal fuses can be conveniently inserted into the mounting boxes and reliably contact the mounting boxes.
Since the highest temperature point of each winding of the transformer occurs at the longitudinal center of the winding, as shown in fig. 2, the first thermal fuse 6 and the second thermal fuse 8 are inserted into the corresponding mounting boxes to such a depth that they are located at the longitudinal center of the winding, so that the highest temperature of the coil can be detected.
When the transformer works, because the temperature of the first mounting box 5 is the same as that of the secondary winding, and the first thermal fuse 6 is in reliable contact with the first mounting box 5, the temperature sensed by the first thermal fuse 6 should be the same as the actual temperature in the first secondary winding 3 and/or the second secondary winding 4 of the transformer. The second mounting box 7 and the second thermal fuse 8 are located at the other side of the ring transformer, symmetrical to the first mounting box 5 and the first thermal fuse 6, and have the same protection mechanism. When the temperature of the transformer winding exceeds the melting point of the thermal fuse made of the fusible alloy (i.e., the operating temperature of the thermal fuse) due to overload or short circuit, the fusible alloy melts, and the melted alloy rapidly shrinks into balls under the action of the special resin, thereby cutting off the current in the primary winding 2. This ensures that when any one of the secondary windings is short circuited or overloaded, the thermal fuse most quickly senses the local maximum temperature of the winding, thereby providing overall thermal protection for the transformer winding.
The action back of thermal fuse is permanent damage promptly, must change new thermal fuse, the utility model discloses the first mounting box 5 and the second mounting box 7 that set up between the coil make the change of thermal fuse very convenient, only need extract the thermal fuse who has damaged from the mounting box, with new thermal fuse reinsert in the mounting box vertical central authorities of winding and rewiring can.
The utility model discloses be different from adopt disposable thermal fuse's transformer among the prior art. In the prior art, a thermal protection device of a transformer generally winds and presses a thermal fuse in a winding directly in the winding process of the transformer, the thermal fuse cannot be taken out after the transformer is manufactured, and the thermal fuse cannot be replaced, so that the thermal fuse cannot be replaced generally. When the thermal fuse is damaged due to overheating of the transformer, the insulating layer of the transformer is not always damaged, but the whole transformer cannot be used continuously due to the fact that the thermal fuse cannot be replaced, and great waste is caused. And the utility model discloses the thermal protection device of transformer takes place the action back at the thermal fuse, only need change new thermal fuse and through withstand voltage test in order to ensure that transformer insulating layer performance is intact. The aging speed of the insulating layer of the transformer is accelerated along with the temperature rise, so that the insulating performance of the insulating layer of the transformer is reduced to a certain extent after the transformer is subjected to short circuit or overload for many times, and the purpose of carrying out a voltage withstanding test is to investigate and confirm the insulating state of the transformer when the transformer is put into use again. After the insulating performance of the transformer is determined to be good, the transformer can continue to be used.
Example 2:
as shown in fig. 4, the present embodiment is different from embodiment 1 in that, on two symmetrical toroidal transformer cores 1, a third secondary winding 11 is further disposed outside a second secondary winding 4, a third mounting box 12 and a fourth mounting box 14 are disposed between the second secondary winding 4 and the third secondary winding 11, and two side surfaces of the third mounting box 12 and the fourth mounting box 14 are in reliable contact with the second secondary winding 4 and the third secondary winding 11, respectively, so as to protect the third secondary winding 11 of the transformer from overheating.
The third mounting box 12 has a third thermal fuse 13 therein, and the fourth mounting box 14 has a fourth thermal fuse 15 therein. Also, the third thermal fuse 13 and the fourth thermal fuse 15 are inserted into the respective installation cases to such a depth that they are located at the longitudinal center of the winding so that the highest temperature of the coil can be detected.
In this embodiment, two mounting boxes are respectively disposed between two symmetrical three secondary coils, and the principle of this arrangement is to ensure that when any winding is short-circuited or overloaded, a thermal fuse is in contact with the highest temperature point of the secondary winding of the transformer, thereby performing full-scale thermal protection on the transformer winding.
Other structures and uses in this embodiment are the same as those in embodiment 1.
Claims (7)
1. A transformer with thermal protection device comprises coil windings and thermal protection device, and is characterized in that the thermal protection device is connected in series in the primary windings, a mounting box for mounting the thermal protection device is arranged between the secondary windings, and the thermal protection device can be mounted in the mounting box and reliably contacted with the secondary windings.
2. The transformer of claim 1, wherein the thermal protection device is positioned in the mounting box at a longitudinal center of the secondary winding.
3. The transformer of claim 2, wherein the mounting box is made of a material having good thermal conductivity, and has a cross-sectional shape adapted to the shape of the thermal protector.
4. A transformer according to claim 3, characterized in that the thermally conductive material of the mounting box is a metallic material, the cross-sectional shape of which corresponds to the shape of the thermal protection means.
5. The transformer of claim 4, wherein the metallic material used for the mounting box is a thin copper sheet.
6. Transformer according to one of the claims 1-5, wherein the thermal protection means is a thermal fuse and the mounting box is rectangular in shape and has dimensions adapted to the cross-sectional dimensions of the thermal fuse.
7. The transformer of claim 6, wherein the thermal fuse is an alloy type thermal fuse.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200009529U CN201011632Y (en) | 2007-01-17 | 2007-01-17 | Transformer with heat protecting equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200009529U CN201011632Y (en) | 2007-01-17 | 2007-01-17 | Transformer with heat protecting equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201011632Y true CN201011632Y (en) | 2008-01-23 |
Family
ID=39046575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2007200009529U Expired - Fee Related CN201011632Y (en) | 2007-01-17 | 2007-01-17 | Transformer with heat protecting equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201011632Y (en) |
-
2007
- 2007-01-17 CN CNU2007200009529U patent/CN201011632Y/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080123 Termination date: 20130117 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |