JPS609648B2 - electromagnetic induction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to evaporatively cooled electromagnetic induction devices, and more particularly to electromagnetic induction devices such as evaporatively cooled transformers.

Cold soot made of gas and steam can be used instead of oil as insulating cold soot used in transformers and other electrical devices that require an insulating medium.

The reason it is not widely used is its economy. That is, compared to the currently known cost of steam as cold soot,
That of oil is only a fraction of that. A recent new technology in the transformer industry that is effective in reducing the amount of expensive liquid insulation required in gas/steam transformers is the development of powder coated insulated wire.

The development of this insulation technology has reduced the insulation required for the winding conductors to a few mils (1/1000 of an inch) thick, reducing the size of the windings and correspondingly reducing the overall size of the transformer to 4.・The amount of liquid dielectric cooler required for evaporative cooling is also reduced. However, in this method of insulation, because of the highly uniform insulation surface coating (which is usually desirable), the distance between adjacent turns of a winding made of such insulated wire is limited. , a problem appeared that liquid cold soot could not pass through. The traditional method of providing cold soot passages with suitable spacing between winding turns, as used in oil-filled transformers, is not suitable for evaporatively cooled transformers using powder-coated wire for several reasons. is not appropriate.

First, insulation structures for oil-filled transformers cannot be used effectively because the potential gradients are very different due to the difference in dielectric coefficients between gas or smoke-cooled soot and conventional oil barriers. Second,
The provision of a solid spacer increases the radial dimensions of the windings, increases the requirement for expensive evaporable cold soot, and increases the size of the transformer itself. Thirdly, if the spacer is inserted between the turns of the winding more than the optimum value, the strength against electromagnetic force in the event of a short circuit will be reduced. For the reasons stated above, it is necessary to avoid the use of solid spacers, which are integrated in order to provide adequate passage for the liquid insulation to span and pass between the surfaces of the induction winding. It would be desirable to have a powder-coated insulated coil with passages that are clear.

Briefly, the invention consists of windings with predetermined irregularities on the surface of the winding turns to form spaces between adjacent portions of the surfaces of the turns through which an evaporable liquid dielectric for cooling and insulation flows. The present invention relates to a new and improved evaporative cooling electromagnetic induction device.

The surface irregularities may be lateral insulating grooves or protrusions formed at predetermined intervals on one side of the long metallic conductor. The specification of this invention also provides for forming grooves at precisely controlled spacing in the surface of a continuously moving long metal conductor and for measuring the spacing of the grooves so formed during manufacture. Also disclosed are methods and apparatus for.

The method includes the step of insulating the grooved conductor to obtain a uniformly solid insulated conductor, with grooves cut at predetermined intervals into one surface of the conductor. . Next, the present invention will be described along with embodiments of the present invention shown in the accompanying drawings. FIG. 1 schematically shows a gas-steam cooled three-phase power transformer.

The transformer has a magnetic core single winding assembly 14 in a tank or enclosure 12, and has C2CI4, C8F, which is evaporable within the normal operating temperature range of the magnetic core single winding assembly. ，
There is a liquid dielectric 16, such as 60. This liquid dielectric 16 is poured onto the core single winding assembly 14 by suitable means such as, for example, a pump 18 and a piping system 20. In addition to this liquid dielectric 16 vapor, a non-condensable gas such as SF6 may be introduced into the enclosure 12 for insulation during commissioning of the transformer 10. The iron core single winding assembly 14 is
The magnetic core 22 and the power source connected to this transformer 10 (
3, one for each phase (not shown).
A set of windings 24 is provided. The winding 24 has a plurality of layers arranged axially, such as layers 26 . As shown in FIG. 2, each layer 26 is comprised of a plurality of radially aligned turns, such as 32, 34, which contact each other at turn surfaces 36, 38, 40, 42. Traditionally, these turns are made using cellulose base.
It was insulated by wrapping it in plastic.

The paper-wrapped turns have enough roughness to allow liquid dielectric to flow between the turn surfaces, coating the windings with a uniform film that evaporates and cools the windings. Ru. Modern powder coating technology allows coating of 2 to 4 mils (0.
．． This makes it possible to deposit an insulator with a uniform thickness (from 0.06 to 0.12 side), making it possible to reduce the radial dimension of the coil. However, when the conductor is insulated with this new solid type of powder coating, the turn surfaces stick together and there is no passageway for the liquid dielectric windings to pass through. Cooling/Insulation The liquid dielectric flows uniformly inside the entire winding to form a film of liquid dielectric covering the turns surface of the coil, which evaporates and most importantly performs its cooling and insulating functions. That's true.

For this purpose, two different solutions were considered. The first was to use solid insulating spacers to form refrigerant ducts throughout the windings, similar to the oil ducts used in oil-filled transformers. This solution is unsatisfactory for several reasons. Such a spacer increases the radial dimensions of the windings and eliminates the space savings provided by powder coated insulation. Also, the use of a solid baser reduces the strength of the coil needed to resist the forces in the event of a short circuit. Most importantly, the potential gradient changes significantly due to the difference in dielectric constant between the gas or smoke refrigerant and the conventional solid barrier. The dielectric constant of gases or vapors is close to 1, whereas the dielectric constant of conventional bulk insulation materials is about 4 to 6. A high permittivity material penetrating a non-uniform or highly stressed field in a gaseous dielectric can significantly increase the corona onset voltage compared to the case without a solid spacer. This can cause dielectric breakdown to occur at low voltages. Some of the preferred configurations for spacers supporting L-coils and windings, such as those used in existing liquid-cooled systems, are based on non-uniformity in an insulating dielectric material with a dielectric constant close to 1. Due to its high dielectric constant, a substrate penetrating through a curved surface is not suitable for use in gas/vapor cooling devices. The simplest and most desirable solution is to avoid using a smoother, and to obtain a powder-coated insulating surface with some form of roughness on the surface so that liquid soot circulation channels are formed inside the windings. be.

This problem is solved because the characteristic of powder coating insulation treatment is surface uniformity, so this is the best way to form irregularities on the surface. Two methods have been used to texture long conductors with a uniform coating of solid, homogeneous electrically insulating material. In the first method, as shown in FIGS. 3-6, the surface of the conductor is coated with equally spaced lateral grooves, such as grooves 48, before the insulation is powder coated. A depression was provided.

The width of these grooves 48 may be, for example, 250 mils wide (on the 6.35 side), and the width of the large side surface 5 of the long rectangular cross-section conductor 50.
It was established on 2. Groove 48 is, for example, 6 mil (0.16 ribs)
This 6 mil depth was maintained even after the insulation was applied with powder coating. The depth of the groove 48 is determined by the depth of the groove 48 relative to the cross-sectional area of the metal conductor 50 (
It is determined that the ratio of the cross-sectional area to be removed at that depth must be the value necessary to give the conductor a predetermined current carrying capacity necessary for the operation of the planned winding. When the insulated conductor 50 with the grooves thus formed is wound into a coil shape to form a winding similar to the winding 24, the liquid cold soot can be successfully transported through the passages formed by these grooves. flowed.
The spacing, depth, and angle of the grooves formed on the conductor 501 with respect to the longitudinal axis D of the conductor (in FIGS. The flow rate of the liquid electrolyte can be controlled by controlling the grooves (the grooves can be provided at any angle on the conductor surface). The groove 48 shown in FIGS. 3 and 4 is hourglass neck shaped (tapered).

Although this shape is not necessary to practice the invention (i.e., straight grooves will work well), it is shown as a preferred embodiment of the invention. These hourglass neck-shaped grooves 48 form hourglass-shaped ducts in some parts of the contact between adjacent turn surfaces 52 when the conductor 50 is wound into a winding, and these ducts The flow of liquid dielectric within the conductor 5 is increased and the barrel shaped portions 56 between these hourglass neck shaped grooves increase the flow of the liquid dielectric within the conductor 5.
0 surface 52 has a surface area sufficient to withstand the constricting force of the conductor when the conductor is wound. Grooves 4 with this unique shape are shown in Figures 5 and 6.
8 and the barrel-shaped portion 56 between them are shown in cross section. Although the shapes of the grooves are straight and hourglass-shaped, the present invention is not limited to specific groove shapes, and includes grooves of all shapes.

The shape of the groove, the angle of the groove, and the dimensions of the groove, as well as the shape of the conductor and the dimensions of the conductor, can be varied without departing from the invention. A schematic diagram of an apparatus for forming precisely spaced grooves in the surface of a continuously moving long metal conductor, such as conductor 50, is shown schematically in FIG.

The groove forming device 60 is a groove forming device 6 such as a router cutter shown in the figure for cutting grooves on the surface of a continuously moving metal conductor.
4, a device 66 such as the illustrated depth indexing device for varying the cutting depth of the groove cutting device 64, and a support device 6 such as the illustrated backing table for supporting a continuously moving long metal conductor.
8 and a frame 62 that supports these devices. Grooving device 64 may be any device capable of forming grooves in a continuously moving long metal conductor, such as a laser cutter or stamping device. The support device 68 may also be any device capable of supporting a continuously moving long metal conductor during groove formation, such as a horizontal support or a series of parallel rollers. The grooving device 60 includes, for example, a combination of a drive belt 70 and a motor speed control 74 to vary the period of operation of the grooving device 64. By changing the period of operation, the groove forming device 64 is controlled to form grooves at predetermined intervals on the surface of a continuously moving long metal conductor such as the conductor 50. 601, the surface 5 of a continuously moving long metal conductor 50
A measuring device 76 is provided to measure the distance between the grooves formed in the grooves 2. The measuring device 76 includes a sensor 78 and this sensor 78
A strobe light 80 and a scale 8 electrically connected to
It consists of 2. The strobe lights 8 are each mounted on the frame 62 on the moving conductor and the scale 82 on the opposite side. The sensor 78 is connected to the groove cutting device 64
The formation of each groove is detected by magnetic, electrical, mechanical, or other methods. FIG. 7A schematically shows one configuration of the sensor 78. In this figure, the router cutter head 84 has an eccentric cam 84 for rotation therewith.
2' is attached. A set of mechanical contacts 86 is provided and the lever arm 88 is biased spring biased towards the eccentric cam 82'.

The eccentric cam 82' rotates together with the cutter head 84.
The contact 86 is opened and closed every rotation of the cutter head 84,
The power supply circuit of the strobe light 80 is momentarily closed, the strobe light 80 momentarily emits light, illuminating the scale 82, and as the formation of each groove is sensed by the sensor 76, a continuous line of newly formed grooves is detected. A long conductor 50 moving to
A predetermined portion of the area is also illuminated at the same time. An instantaneous still image of the moving conductor 50 is then made at the location of the scale 82, and the machine operator adjusts the operating cycle of the groove forming machine by comparing the spacing between the grooves and the scale's memory. , grooves can be formed in the surface 62 of the moving long conductor 50 at defined intervals. Surface 52 of conductor 50
In order to cause the groove 48 formed in the cutter head 84 to have an hourglass neck shape as described above, the cutter head 84 is provided with a concave and convex cutting tool 90 as shown in FIG. 7B.

Both ends of the concave surface 92 of this cutting tool 90 are connected to both ends of the surface 52 of the continuously moving conductor 50.
The central portions of the grooves 2 and 2 contact each other deeper and from earlier to later, forming an hourglass neck shape such as this groove 48. Returning to FIG. 7, the groove forming device 60 is operated,
As a continuously moving long conductor, such as conductor 50, passes between the groover 64 and the support 68, grooves are formed in the surface 52 of the conductor.

The formation of each groove is sensed by the sensor 78, the circuit of the strobe light 80 is closed, and in synchronization with the sensing of the formation of each groove, the strobe light emits light and the newly grooved continuously moving long A defined portion 94 of conductor 50 and scale 82 are momentarily illuminated to provide an instantaneous static image of this portion 94. The operator compares the groove spacing in this instantaneous static image with the desired spacing on the scale 82, measures the distance between the grooves, changes the operating cycle of the groove cutting device 64, and adjusts the speed of the drive motor 72. Then, by changing the angular velocity of the cutter head 84, the surface 52 of the conductor 60 is
Grooves can be formed at desired intervals. After grooves are formed in the surface 52 at predetermined intervals, the conductor 50' is passed through an electrostatic powder coating device, generally designated 110, and a conductor heating device, generally designated 112, to uniformly coat the conductor 50'. A uniform solid insulation coating is obtained.

A continuously moving long conductor with a rectangular cross section, such as the conductor 50, is surrounded by a uniform layer of solid, solvent-free, finely powdered resinous polymer powder that is heated, melted, and hardened to generate electrostatic charges. An apparatus and method for applying a powder coating is disclosed in U.S. Pat. No. 405
180 shouts' have been disclosed.

Electrostatic powder coating equipment 110 with a uniform coating of heat-melted, solvent-free resinous polymer powder, such as epoxy resin powder.
1. Therefore, powder coating is applied electrostatically around the conductor 60 in which grooves have been formed in advance, and the grooved conductor 50 having a uniform coating is heated to a predetermined temperature in the heating device 112. Ru. Regarding the above-mentioned epoxy resin composition,
A temperature of approximately 500°C is suitable for melting the powder particles of the insulating material into a uniform, homogeneous coating of solid insulating material. 50 is
The feature is that a uniform and homogeneous insulating coating can be obtained, that is, the insulating material of the same thickness as the insulating material of other parts is deposited even in the groove part of the conductor. A second method used to create irregularities on the surface of a long conductor, such as the conductor 50 with a uniform coating of a solid electrical insulator described above, is to create irregularities on the surface of the insulator itself. , warts or bumps are added at predetermined intervals. A device for this purpose is shown in FIG. In this device, a compressed rod-shaped insulating powder 120 is chopped into pieces and dropped onto a continuously moving long conductor, which is coated with the electrostatic powder coating described above. Pass through equipment and heaters. In this way, the finely chopped compacted powder insulation and the uniform coating of powder particles of the same insulation powder are melted to form voids of insulation at defined intervals. Alternatively, it is a uniform and homogeneous coating of solid insulator with bumps, resulting in unevenness on the surface of the insulated conductor. In summary, in order to allow the evaporable dielectric liquid to flow inside the winding, a long An evaporative cooled electrical induction device is disclosed that includes windings formed using metallic conductors.

Although this invention was made to solve a problem in the transformer industry, this invention is not limited to those used in transformers, but is applicable to all evaporatively cooled electrical equipment. Surface asperities formed on the surface of the insulated winding turns to provide a uniform finish for the conductor and to provide space for the flow of evaporable liquid fluid within the winding. It should be understood that it is possible to combine and implement the following cases.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an evaporative cooling electrical device according to an embodiment of the present invention; FIG. 2 is a top view showing the coil layers of the device of FIG. 1; FIG. A top view of the grooved conductor, Figure 4 is a side view of the conductor in Figure 3, and Figure 6 is a side view of the conductor in Figure 3.
FIG. 6 is a cross-sectional view of the conductor of FIG. 3 along line -W; FIG. FIG. 7A is a schematic diagram of the sensor of the device of FIG. 7; FIG. 7B is a diagram showing an apparatus for forming grooves with precisely controlled spacing on the surface of a conductor;
This figure shows a cutting tool used in the apparatus shown in FIG. 7, and FIG. 8 schematically shows another embodiment of the apparatus for forming warts in a uniform coating of an insulating material. 12...Enclosure, 14...Magnetic core single winding assembly, 16.
...Liquid dielectric, 18...Pump, 20
...Pipe device, 24...Winding, 26...
・...Layer, 32, 34...Turn, 36, 38, 40, 4
2... Turn surface, 48... Groove on conductor surface, 50... Conductor, 52... Conductor surface,
56... Barrel-shaped portion on the conductor surface (portion sandwiched between grooves). FIGI FIG2 F! G3 FIG4 F! G5 FIG6 FIG. 7 FIG, 7A FIG. 78 FIG. 8.

Claims (1)

Claims: 1. An enclosure having at least two circumferentially adjacent turns of an insulated conductor disposed within the enclosure and having homogeneously solid insulated turn surfaces in circumferential contact with each other. , an electrical winding that generates heat during normal operation; a liquid dielectric disposed within said enclosure to a predetermined level, having a predetermined viscosity, and evaporating within the normal operating temperature range of said winding; a liquid dielectric distributed over the windings to cool and insulate the windings, at least one of the turn surfaces having a predetermined surface ridge formed thereon during manufacturing; An electromagnetic induction device in which a space is formed between circumferentially adjacent portions of the surface in which the liquid dielectric flows in the axial direction. 2. The winding has a plurality of axially adjacent layers, each said layer comprising a plurality of radially adjacent turns having homogeneous solid insulation in contact with each other on said turn surfaces. An electromagnetic induction device according to claim 1. 3. The electromagnetic induction device according to claim 1, wherein the surface ridge is formed by a plurality of lateral depressions formed at predetermined intervals along the length of the insulated turn surface. 4. the conductor is homogeneously insulated by a deposited non-layered insulator, the ridge being provided on the surface of the insulating turn at a predetermined angle to the longitudinal direction of the conductor and having a predetermined width and depth; 4. The electromagnetic induction device according to claim 3, comprising a plurality of grooves.