JP2002064026A - Grounding instrument transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grounding instrument transformer which is superior in insulation against sharp voltage and of which winding part can be manufac tured easily. SOLUTION: In this grounding instrument transformer, a primary winding 8 and a secondary winding 7 wound like a multi-layer cylinder by an electric wire 12 with an interlayer insulation paper 11 in between are arranged coaxially, and their axial centers are assembled to a two-leg iron core 1. A projecting part 11a of V-shaped rotary axis section is formed at both ends of the interlayer insulation paper 11 for primary winding. In addition, the length of the primary winding 8 in the axial direction is wound similarly from the innermost layer of the winding to outermost layer thereof, and the electric wire 1 is wound thicker stepwise from the innermost layer toward the outermost layer. Furthermore, a tightening band 9 is attached between the outermost layer of the primary winding 8 and a high-voltage shield 3 as a shield for releasing electric field, thereby tightening and holding the primary winding 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winding structure of a grounding type instrument transformer which is housed in a sealed container filled with an insulating gas.

[0002]

2. Description of the Related Art A primary circuit is formed by connecting one end of a primary winding to a bus side and the other end to a ground side to transform a primary winding voltage to a low voltage and to provide a voltmeter to a secondary winding. A transformer for a grounded instrument, which is operated by connecting a power supply and a relay, is an indispensable electric device for power receiving and distribution equipment as an abnormal voltage detection sensor for voltage measurement and circuit protection. Generally, a grounding-type instrument transformer used for electrical equipment of 66 kV or more has a primary winding and a secondary winding in which electric wires are wound in a multilayer cylindrical shape with an interlayer insulating paper interposed therebetween, and is arranged coaxially. its cylinder center axis bipod core is assembled, is further bushing and secondary terminal box is provided, accommodated in the sealed container enclosing an insulating gas such as SF ₆ gas.

[0003] Here, the primary winding of a grounding type instrument transformer is
From the beginning to the end of the winding, it must be wound in a multilayer cylindrical shape with the same winding width, and the entire coil is molded with epoxy resin, etc. Insulating paper and electric wires were fixed with adhesive tape or adhesive. 6 shows a structure in which the electric wire 12 and the interlayer insulating paper 11 are covered with a mold resin 13, FIG. 7 shows a structure in which the electric wire 12 and the interlayer insulating paper 11 are fixed with an adhesive tape 14, and FIG. The structure in which the paper 11 is fixed with the adhesive 15 is shown.

Also, as is well known, when a steep voltage (lightning impulse waveform) is applied from the bus side to the winding of a grounded instrument transformer, the voltage applied to one winding of the winding is not uniform, As shown in FIG. 9, it is known that the pressure increases as the pressure increases. Therefore, it is necessary to increase the strength of the interlayer insulation at the high voltage end as compared with the low voltage side. Therefore, as shown in FIG. 10, the number of turns of the primary winding per layer may be gradually reduced as the winding is advanced to the high voltage side. FIG. 11 shows a configuration in which the number of turns on the low-pressure side is the same as the maximum number of turns on the highest pressure end.

[0005]

However, as described above, large-scale casting equipment is required to mold the windings with resin, and large-sized windings such as the windings of a transformer for an ultra-high-voltage instrument are formed of resin. In order to mold, an advanced casting technique is required to prevent voids. Also, interlayer insulating paper 2
The structure in which the wire 1 is fixed with the adhesive tape 4 has a problem that the adhesive strength is reduced by heat and the strength against impact is reduced.

Further, in the structure in which the interphase insulating paper 11 and the electric wire 12 are fixed with the adhesive 15, an extra step for heating and hardening after completion of the winding is required, or the adhesive 15 may be used.
However, there are disadvantages such as the uneven size of the coil due to the variation in the coating amount, and the occurrence of partial discharge due to the formation of minute voids. As a measure against steep voltage, FIG.
When the method as shown in FIG. 11 is used, several types of jigs for adjusting the position of the winding are prepared, and there is a trouble that a special winding machine is used. When the method as shown in FIG. There were problems such as an increase in size.

[0007]

In order to solve the above-mentioned problems, the present invention provides a primary winding and a secondary winding in which electric wires are wound in a multilayer cylindrical shape with an interlayer insulating paper interposed therebetween. A grounding-type instrument transformer in which a two-leg iron core is attached to the shaft center of the transformer, an interlayer insulating paper for a primary winding having a convex portion having a cross section of a rotating shaft at both ends, and an axial length. The primary winding is wound with the same winding from the innermost layer to the outermost layer, and the wire diameter is gradually increased from the innermost layer to the outermost layer. And a tightening band that is mounted between the first and second shields and tightens and holds the primary winding.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view of a grounded-type instrument transformer according to the present invention, and FIG. 2 is a side view of FIG. In both figures, 1 is an iron core, 2 is a winding, 3 is a high voltage shield which is a shield for electric field relaxation, 4 is a ground shield,
Reference numeral 5 denotes a frame constituting the legs of the two-leg iron core.

FIG. 3 is an external view showing a part of the winding 2 extracted from FIG. In the figure, 6 is a winding core, 7 is a secondary winding wound outside the winding core 6, 8 is a primary winding wound outside the secondary winding 7, 9 is a primary winding 8. It is a fastening band wound outside. By fastening both ends of the tightening band 9 with the bolts 10, the tightening band 9 tightens and holds the primary winding 8 with a predetermined tension.

FIG. 4 is an enlarged sectional view showing a part of the primary winding 8 and the tightening band 9 of FIG. In the figure, reference numeral 11 denotes an interlayer insulating paper, and both ends in the axial direction are bent into a U-shaped cross section to form a convex portion 11a. The projection 11a serves as a guide when the electric wire 12 is wound, thereby preventing the wire from dropping in the middle of the winding and improving the workability of the winding operation.

Further, the outer side of the outermost interlayer insulating paper 11 is fastened by the fastening band 9 so that the convex portions 11 are formed.
a contact each other in the thickness direction, and the interlayer insulating paper 11 is stably held against an impact in the axial direction. Further, the primary winding 8 is constituted only by the interlayer insulating paper 11 and the electric wire 12,
Since no other adhesive or the like is interposed, the winding can be formed with a uniform thickness, and the probability of occurrence of partial discharge is reduced because no high dielectric material such as an adhesive is interposed.

FIG. 5 is a sectional view showing the entire thickness of the primary winding 8. As shown in the figure, the electric wire 12 constituting the primary winding 8 has three types of thicknesses, and the thinnest electric wire 12A inside.
Is wound around a wire 12B of an intermediate thickness on the outside, and the thickest wire 12C is wound on the outside, and the axial length is the same from the innermost layer to the outermost layer. It is wound. Thus, the electric wire 1 of the primary winding 8
The number of turns is reduced by gradually increasing the diameter of No. 2 as it moves from the low pressure side (inside) to the high pressure side (outside), and the voltage applied to one layer of the winding can be reduced stepwise. become.

Further, since the diameter of the electric wire increases as the wire is wound outward, the interlayer electric field at the high voltage end is also reduced synergistically,
The strength of the insulation is strengthened compared to the low pressure side. Further, since the low voltage side can be wound until the interlayer voltage becomes full, the size can be reduced as compared with the case where the low voltage side is manufactured with a uniform interlayer voltage from the low voltage side to the high voltage side. Moreover,
In manufacturing, it is only necessary to sequentially wind electric wires having different diameters, so that no special jig or winding machine is required in the process. In addition, in the embodiment, the diameter of the electric wire 12 is set to three types, but it is also possible to further reduce the number to four or more types.

[0014]

As described above, according to the present invention, since the protrusions are formed at both ends of the interlayer insulating paper, displacement and drop of the winding are prevented, and the winding operation is facilitated. In addition, by gradually increasing the diameter of the electric wire, the voltage applied to one layer can be gradually reduced, and by reducing the interlayer electric field at the high voltage end, the insulation strength can be strengthened as compared with the low voltage side. Further, by tightening the outermost layer of the primary winding with a tightening band, the convex portions of the interlayer insulating paper of the primary winding are held in contact with each other in the vertical direction, thereby being stabilized against an axial shock.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a grounded-type instrument transformer according to the present invention.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is an external view showing a winding part taken out from FIG. 1;

FIG. 4 is an enlarged sectional view showing a part of a primary winding and a tightening band of FIG. 3;

FIG. 5 is a sectional view showing the entire thickness of the primary winding.

FIG. 6 is a sectional view showing a conventional example.

FIG. 7 is a sectional view showing a conventional example.

FIG. 8 is a sectional view showing a conventional example.

FIG. 9 is a graph showing a relationship between the number of turns and a potential.

FIG. 10 is a sectional view showing a conventional example.

FIG. 11 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron core 2 Winding 3 High voltage shield 4 Ground shield 5 Frame 6 Core 7 Secondary winding 8 Primary winding 9 Tightening band 10 Bolt 11 Interlayer insulating paper 11a Convex part 12, 12A, 12B, 12C Electric wire

Claims (1)

[Claims] 1. A primary winding and a secondary winding in which electric wires are wound in a multilayer cylindrical shape with an interlayer insulating paper interposed therebetween, and coaxially arranged.
A grounding-type instrument transformer with a two-leg iron core attached to its axis, an interlayer insulation paper for primary winding with convex portions with a cross section of the rotating shaft formed at both ends, and an axial length A primary winding wound around the same layer from the innermost layer to the outermost layer, with the wire diameter gradually increased from the innermost layer to the outermost layer, and an outermost layer of the primary winding and a shield for electric field relaxation A grounding type transformer for a transformer, comprising: