JPH065442A - On-load tap changer - Google Patents

Abstract

PURPOSE:To assume reliability of ground insulation and to realize a low-cost on-load tap changer by filling/molding conductive filler in a bolt clamping spot facing hole of oil-air-tight structure member, and imparting a function equivalent to an electric field shielding for alleviating an electric field of a ground side to he filler. CONSTITUTION:A head 3 is mounted on a transformer cover, and an insulation cylinder 4 is mounted in an oil-air-tight structure. A bottom 11 is mounted at a lower part of the cylinder 4, and an oil-air-tight vessel partitioned from a transformer chamber is constituted. A top 3 is clamped through a 'spot facing hole' 13 of a retaining ring 6 with a bolt 7. Conductive filler 20 is filled along a circular arc of the ring 6 in the hole 13 of the ring 6. Thus, a function for alleviating an electric field of a ground side can perform a role equivalent to that of a conventional electric field shield 10. Accordingly, an expensive electric field heretofore separately provided in a prior art is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load tap changer for adjusting the voltage on the load side by changing the tap of a transformer tap winding when a load is applied.

[0002]

2. Description of the Related Art A power transformer for supplying high-quality electric power is equipped with a load tap changer for adjusting the voltage on the load side in response to fluctuations in the load. As the load tap changer, a resistance type using a resistance as a current limiting impedance is most popular. An example of this resistance type will be described with reference to FIGS.

In FIG. 5, reference numeral 16 denotes a transformer tank cover on which the head 3 is oil-tightly mounted. Reference numeral 1 is a transmission mechanism for transmitting power from an electric operation mechanism (not shown) to the cutoff portion 10, and is attached to the lid 2. An insulating cylinder 4 is attached to the head 3 at the upper part and to the bottom 11 at the lower part to form an oil / airtight container. A tap selector 12 is attached so as to be suspended from the bottom 11 and connected to a tap winding (not shown). Reference numeral 10 is a cutoff portion for cutting off the load current, which is hung from the transmission mechanism 1 by the insulating cylinder 8 and the current is opened and closed by its power. 9 and 15 are electric field shields, 9 is a cut-off portion, that is, for electric field relaxation on the high voltage side, 15
Is for relaxing the electric field on the ground side.

FIG. 6 is a detailed view of the Y portion of FIG. 5, that is, the oil / airtight structure of the head 3 and the insulating cylinder 4. As shown in the figure, reference numeral 5 is an O-ring made of a rubber material, which is located in the groove portion of the head portion 3 and keeps oil and airtightness between the inner peripheral surface of the insulating cylinder 4 and the groove surface. Reference numeral 6 is a holding ring for holding the protrusion of the O-ring 5, which is fastened to the head 3 by a bolt 7.
Reference numeral 13 is a countersunk hole for allowing the bolt 7 to be tightened, and 14 is a detent for the bolt 7.

[0005]

By the way, since the breaking portion 10 for breaking the load current is for switching the current, it is composed of complicated mechanical elements and, since it is frequently switched, it is used for a certain period of time. Must be regularly inspected.

In order to perform this inspection easily, it is necessary to completely isolate the insulating medium from the insulating medium of the transformer body. Therefore, the oil / airtight structure shown in FIG. 6 is adopted. Since the holding ring 6 serves as a charging portion and a counter electrode, the lower surface forms an arc, but there are a plurality of counterbore holes 13, and the corners of the counterbore holes 13 cause electric field concentration. Therefore, the electric field shield 15 shown in FIG. 5 is provided to eliminate the electric field concentration on the corners of the countersunk hole 13. If the shield 15 is structured to be supported from the head 3 side, it will be an obstacle when lifting the blocking portion 10 at the time of inspection, and the insulating cylinder 4 must be made large, which is not economical.

Therefore, the shield 15 must be supported by the insulating cylinder 8. Therefore, a shield covering a wide range from the small-diameter insulating cylinder 8 to the inner peripheral portion of the head 3 must be attached, and the tubular shield cannot sufficiently achieve the purpose of relaxing the electric field. Therefore, a thin plate is used. Inevitably, a shield formed into a curved shape was used. As described above, since the shield on the ground side is formed by bending the thin plate into a curved shape, there is a drawback that the processing cost increases and the cost becomes high.

The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide an inexpensive tap changer for load while ensuring reliability of ground insulation without providing an expensive electric field shield. It is in.

[0009]

In order to achieve the above object, the present invention has a head attached to a ground potential on a transformer cover, is fixed to the head by an oil / airtight structural member, and has a tap winding. In a load tap changer provided with an insulating cylinder for maintaining ground insulation with a charging part connected to the above, by filling and molding a conductive filler into the bolt tightening hole of the oil / airtight structural member, It is characterized in that the filler has a function equivalent to that of an electric field shield for relaxing an electric field on the ground side.

[0010]

[Function] After the assembly of the O-ring with the press ring to tighten the tightening oil and airtight structure, the conductive charging agent is injected into the counterbore hole part of the press ring, and it is molded along the arc of the bottom surface of the press ring to complete the counterbore hole. Since it is filled to have a function as an electric field shield, it is not necessary to provide an expensive electric field shield provided only for relaxing electric field concentration in the counterbore hole.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the present invention. In the figure, 1 is a transmission mechanism for transmitting power to the cutoff portion 10,
It is mounted on the lid 2 and fixed to the head 3. Breaking part 1
0 is hung on the lid 2 via the support insulating cylinder 8. Head 3
Is mounted on the transformer cover and the insulating cylinder 4 is mounted in the oil / airtight structure shown in FIG. The bottom of the insulating cylinder 4 is the bottom 1
1 is installed to form an oil / airtight container that is isolated from the transformer room. Reference numeral 9 is an electric field shield of the high voltage portion of the cutoff portion 10. A tap selector 12 is connected to a tap of a tap winding (not shown).

FIG. 2 is a perspective view as seen from the direction of the arrow of line II of FIG. 1, and FIG. 3 is a detailed view of the X portion of FIG. 1, showing the oil / airtight structure of the insulating cylinder 4 and the present invention. It is sectional drawing which shows the detail of the pressing ring which has an electric field relaxation function.

In FIG. 1, an O-ring 5 is attached to the groove portion of the head portion 3 and is sandwiched between the inner peripheral surface of the insulating cylinder and the groove surface to maintain airtightness. Reference numeral 6 is a pressing ring that presses the protrusion of the O-ring 5 and has a lower surface formed in an arc shape to serve as a counter electrode with the lower shield 9. A bolt 7 is fastened to the head 3 through the "counterbore hole" 13 of the pressing ring 6. As shown in FIG. 2, this counterbore hole 13 is
The O-rings 5 are evenly tightened by being arranged at six equal intervals.

Reference numeral 20 denotes a conductive filler filled in the counterbore hole 13 of the holding ring 6, which is filled along the arc of the holding ring 6 as shown in the figure. As a result, the counterbore hole 13 of the pressing ring 6 secures an arc surface by the filler 20, and the function of relaxing the electric field on the ground side plays the same role as that of the conventional electric field shield 10. Therefore, an expensive electric field shield, which is conventionally provided separately, is not required.

FIG. 4 shows a method of forming an arc portion for injecting the filler 20 into the counterbore hole 13 of the holding ring 6 to fulfill the function as an electrode. For convenience of explanation, this figure is shown in the opposite direction to the attached state of FIG.

Reference numeral 21 denotes an injection / molding jig for injecting the filler 20 and for forming an arc portion. The lower surface portion which contacts the holding ring 6 is a concave arc portion having the same shape as the arc portion of the holding ring 6. Six injection holes 23 for the filler 20 are provided at positions corresponding to the upper end and the counterbore holes 13. Further, it has a plurality of grips 22 on its circumferential portion and plays a role of moving and carrying for molding after injection.

First, the injection jig 21 is firmly attached to the circular arc portion of the pressing ring 6 as shown in FIG. 4, and the injection hole 23 is aligned with the center of the countersunk hole 13. In this state, place a weight of an appropriate weight to hold down the jig and stabilize it. Next, the filler is injected into the injection hole 23 from a tube or the like, and is injected in the same manner at six places up to about half the depth of the injection hole 23. When the injection is completed, the air remaining inside the counterbore hole 13 is released to the outside, and it is left for a while.

After leaving the air for a while, the jig 22 is slowly rotated clockwise (indicated by an arrow in the figure) by the handle 22 of the injection jig 21 to rotate the injection hole 23 to a substantially central position between the counterbore holes 13 and leave it for a while. To do. The tip of the injection hole 23 is small so as not to interfere with the injection. The filler remaining in the injection hole 23 due to this movement is cut at the tip of the injection hole and moves together with the injection hole. The filler remaining in the counterbore 13 gradually solidifies while contacting the concave arc surface of the jig.

If the jig 21 is removed after being left for a predetermined time, the counterbore hole 13 of the pressing ring 6 is formed in an arc shape by a filler. It is the same as a general cast product that the mold release agent or the like is applied to the concave arc portion of the jig 21 in advance.

The filler (or adhesive) used here is electrically conductive and has fluidity, has high adhesion to the metal after curing, and is preferably room temperature curing type. For example, a paste of silicone-based conductive RTV rubber or a conductive adhesive containing amalgam as a main component is most suitable for this purpose. The point is that there is no particular limitation as long as it is a conductive filler that can achieve the above-mentioned performance.

As described above, according to this embodiment, since the holding ring for holding the O-ring has the function of an electrode, it is not necessary to newly provide an electric field shield, which is cheaper than the conventional one. Can be manufactured. Furthermore, since the bolts are also covered with a filler, a locking effect is inevitably produced,
As in the prior art, the effect of not requiring a rotation stopping member is produced.

[0022]

As described above, according to the present invention, a function similar to that of an electric field shield is added by filling and molding a conductive filler into the bolt counterbore holes of the oil / airtight structural member. Since there is no need to provide an expensive electric field shield to alleviate the electric field concentration in the counterbore as in the past, it is possible to provide reliable ground insulation and provide an inexpensive tap changer at the time of loading. become.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a view seen from the direction of the arrows I-I in FIG.

FIG. 3 is a detailed view of an X portion of FIG.

FIG. 4 is a diagram for explaining a method of injecting a filler.

FIG. 5 is a sectional view of a conventional device.

6 is a detailed view of a Y portion of FIG.

[Explanation of symbols]

1 ... Transmission mechanism, 2 ... Lid, 3 ... Head, 4, 8 ... Insulation cylinder, 5
... O-ring, 6 ... Pressing ring, 7 ... Bolt, 9 ... Shield, 10 ... Separator, 11 ... Bottom, 12 ... Tap selector, 13 ... Counterbore hole, 20 ... Filler, 21 ... Injection jig,
22 ... Handle, 23 ... Injection hole.

Claims (1)

[Claims] 1. An insulating cylinder having a head attached to a ground potential on a transformer cover, fixed to the head by an oil / airtight structural member, and maintaining ground insulation with a charging part connected to a tap winding. In the provided tap changer, the same as an electric field shield that fills and molds a conductive filler into the bolt counterbore hole of the oil / airtight structural member to relax the electric field on the ground side in the filler. A tap changer under load, which is characterized by adding functions.