JPH01227411A - Mold-type instrument transformer - Google Patents

Abstract

PURPOSE:To keep damage introduced by a secondary short from spreading to the inside of a distributor and to minimize the damage by burying a reinforcing material made of glass fiber or other substance at a position on a side of high-voltage bushing in an insulating wall. CONSTITUTION:A secondary winding 2 and a primary winding 3 are wound round an iron core 1. Outside the wound portions, a primary terminal 6 is positioned. An insulating wall 8 is formed from mold material so that a high- voltage bushing 7 to support the primary terminal 6, the iron core 1 and the windings 2 and 3 are mounted in a body inside the insulating wall. The unified equipment is installed on a distributor, with the high-voltage bushing 7 positioned inside the distributor and the insulating wall 8 outside. In this system, a reinforcing material 11 made of glass fiber or other substance is buried at the site 8a near the high-voltage bushing 7 in the insulating wall 8. As a method of burying the reinforcing material, the mat-shaped glass fiber-made reinforcing material 11 can be set at the portion where the high-voltage bushing is molded prior to molding of the insulating wall 8. By this method, the reinforcing material 11 can be buried inside the insulating wall 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a molded potential transformer having an improved molded insulation wall.

(Prior art) Traditionally, molded instrument transformers have been used as instrument transformers that supply voltage exclusively to measuring instruments in power distribution systems because of their high insulation reliability and their suitability for compact metering. Many shapes are used.

On the other hand, power distribution equipment such as switchboards to which the instrument transformers are attached tend to adopt gas insulation methods instead of the conventional atmospheric insulation method because they can be made smaller and space-saving.

Figure 2 shows a general example of a molded voltage transformer installed in such a gas-insulated switchboard.
are sequentially wound concentrically through an insulator 4.5,
A primary terminal 6 is arranged outside the radial direction (downward in the figure) of the windings 2 and 3, and a high-voltage bushing 7 that supports the primary terminal 6 and the windings 2 and 3 of the iron core 19 are installed inside. The insulating wall 8 is constructed by integrally forming a molding material such as epoxy resin using a mold (not shown). In the molded instrument transformer constructed in this way, the high-voltage bushing 7 is inserted into the through hole 1o formed in the metal box 9 that constitutes the outer wall of the gas-insulated switchboard.
Therefore, this high-voltage bushing 7 is located inside the gas insulated power distribution board, with the insulating wall 8 located outside, and is attached to the gas insulated power distribution board using bolts (not shown). In the above configuration, the thickness of the insulating wall 8 between the primary winding 3 at high voltage potential and the box body 9 at ground potential is set to be sufficiently thicker than the others in order to moderate and reduce the electric field between the two. It is largely determined.

(Problem to be solved by the invention) In the secondary circuit of a voltage transformer, short circuits occur relatively often due to two-point grounding due to wiring errors, changes in circuit wiring, or forgetting to remove temporary grounding during remodeling. ing. When such a secondary circuit is short-circuited, an excessive secondary current flows, and copper loss rapidly increases in the winding. On the other hand, there are cases where fuses are not installed in the secondary circuit due to measurement of the power receiving and distribution system, and protection is prioritized, or even if fuses are installed, a short circuit occurs upstream from the point where they are installed. In some cases, if the short-circuit condition continues for a long time, the winding section becomes overheated, and the insulation coating of the wire, the insulators 4 and 5, and the mold insulation wall 8 around the winding section melt and gasify. progress to. Further, due to the increase in gas pressure inside the insulating wall 8 due to its melting and gasification, the insulating wall 8 develops into cracks and scattering, leading to the flow and release of the melt and gas inside the insulating wall 8.

Cracks caused by an increase in gas pressure inside the bipedal insulating wall 8 mainly originate from the outer periphery of the winding, and propagate in various directions from there depending on the strength of the insulating wall 8.

In the conventional device shown in FIG. 2, in order to simplify the structure, facilitate manufacturing, and stabilize quality, the
The primary terminal 6 and the high-voltage bushing 7 are arranged radially outward of the secondary short circuit, but cracks in the insulating wall 8 caused by the secondary short circuit propagate to the high-voltage bushing 7 and its base. There is plenty of possibility. If the crack develops in the high-voltage bushing 7 and its base and causes the high-voltage bushing 7 to scatter, the high-voltage bushing 7 is located inside the switchboard, and therefore the high-voltage bushing 7 and the primary Scattered objects from the terminals 6 and the insulating wall 8, melted material inside the insulating wall 8, etc. enter the inside of the switchboard and cause great damage. For this reason,
The problem was that the restoration work required a great deal of cost and time.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an excellent mold that can prevent damage caused by secondary short circuits from spreading to the inside of power distribution equipment, thereby minimizing the damage. To provide type potential transformers.

[Structure of the Invention] (Means for Solving the Problem) The molded potential transformer of the present invention has a secondary winding and a primary winding wound around an iron core, and a primary winding located outside the winding portion. A high-voltage bushing supporting the primary terminal and an insulating wall housing the first winding of the iron core are integrally formed with a molded material, and the high-voltage bushing is located inside the power distribution equipment, It is mounted with an insulating wall located on the outside, and is characterized in that a reinforcing material made of glass fiber or the like is embedded in a portion of the insulating wall on the high-pressure bushing side.

(Function) According to the above means, the strength of the portion of the insulating wall of the molded potential transformer on the high-voltage bushing side is made greater than that of other portions. For this reason, cracks in the insulating wall caused by secondary short circuits will occur in other parts of the insulating wall with lower strength before they occur in the part on the high-pressure bushing side. , the propagation of cracks in the high-voltage bushing and its base located inside the power distribution equipment is avoided.

(Example) An example of the present invention will be described below with reference to FIG.

In FIG. 1, the same parts as in FIG. A secondary winding, 3 is a primary winding wound around the secondary winding 2 via an insulator 5, and thus wound around the iron core 1 concentrically with the secondary winding 2, 6 is a primary winding 2 of these windings.
．． 3 is a primary terminal located outside in the radial direction (lower part in the figure), 7 is a high-voltage bushing that supports the primary terminal 6, and 8 is an insulating wall containing the iron core 1 and windings 2 and 3. The high-pressure bushing 7 and the insulating wall 8 are integrally formed with a molding material such as epoxy resin using a mold (not shown).

In contrast, reference numeral 11 denotes a reinforcing material made of, for example, mat-like glass fibers, which is set in advance in a portion of the mold on the side where the high-pressure bushing 7 is molded when the insulating wall 8 is molded, and then By performing molding, the portion 8a of the insulating wall 8 on the high pressure bushing 7 side is
This reinforcing material 11 is buried in.

Reference numeral 9 denotes a box constituting the outer wall of a gas-insulated switchboard, which is a power distribution device, and 10 denotes a through hole formed in the box 9. The high voltage bushing 7 in the insulating wall 8 is inserted into this through hole 10 as described above.
A high-voltage bushing 7 in a molded instrument transformer formed by embedding a reinforcing material 11 is inserted into the side portion 8a, so that the high-voltage bushing 7 is located inside the switchboard, and the insulating wall 8 is placed on the outside. The molded instrument transformer is attached to a gas insulated switchboard indicated by a box 9 using bolts (not shown).

Now, in the case of the structure as described above, in the insulating wall 8 of the molded voltage transformer, the strength of the portion 8a on the high voltage bushing 7 side is the same as that of the reinforcing material 11 buried therein.
It is made larger than other parts. Therefore, cracks in the insulating wall 8 due to the secondary short circuit described above are caused by the insulating wall 8.
Before it occurs in the area 8a of the high-voltage bushing 7 inside, it begins to occur in the area around the winding where the strength is low, and as a result, the high-voltage bushing 7 located inside the switchboard
and the propagation of the crack at its base is avoided,
Damage caused by cracks and scattering is prevented from reaching the inside of the switchboard. Therefore, damage caused by cracks and scattering of the insulating wall 8 can be minimized.
In particular, it is possible to avoid requiring a great deal of cost and time to restore the inside of the switchboard.

Note that the device to which the molded instrument transformer is attached is not limited to a gas-insulated switchboard, but may be other power distribution devices such as a gas-insulated switch. Furthermore, the reinforcing material 11 is not limited to being made of glass fiber, but may be made of other materials as long as it has the same strength and insulation properties.

[Effects of the Invention] As is clear from the above description, the molded potential transformer of the present invention has a secondary winding and a primary winding wound around an iron core,
A primary terminal is arranged outside the windings, and a high-voltage bushing that supports this primary terminal and an insulating wall that supports the two iron core windings are integrally formed using a molding material, and the power distribution equipment is equipped with the following: The high-pressure bushing is located on the inside and the insulating wall is located on the outside, and a reinforcing material made of glass fiber or the like is buried in the part of the insulating wall on the high-pressure bushing side. This feature has the advantage of being able to prevent damage caused by secondary short circuits from spreading to the inside of the power distribution equipment, thereby minimizing the damage.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing one embodiment of the present invention, and FIG. 2 is a vertical sectional view of a conventional device. In the drawing, 1 is the iron core, 2 is the secondary winding, 3 is the primary winding, 6 is the primary terminal, 7 is the high-voltage bushing, 8 is the insulation wall, 9 is the box of the switchboard (power distribution equipment), and 11 is the reinforcing material. shows. Agent Patent Attorney Aide Kensuke Daishimaru

Claims (1)

[Claims] 1. A secondary winding and a primary winding are wound around an iron core, a primary terminal is arranged outside the windings, a high voltage bushing supports the primary terminal, and an insulating wall houses the iron core and the winding. is integrally formed with a molded material and is attached to a power distribution device with the high voltage bushing located inside and an insulating wall located outside, wherein the high voltage bushing in the insulating wall A molded instrument transformer characterized in that a reinforcing material made of glass fiber or the like is embedded in the side portion.