JP3932086B2 - Grounded instrument transformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a winding structure of a grounding-type instrument transformer that is housed in a sealed container filled with an insulating gas.
[0002]
[Prior art]
One end of the primary winding is connected to the busbar side and the other end is connected to the ground side to form a primary circuit. The primary winding voltage is transformed to a low voltage, and a voltmeter and relay are connected to the secondary winding. The grounding-type instrument transformer that is operated in this way is an indispensable electrical device for receiving and distributing equipment as an abnormal voltage detection sensor for voltage measurement and circuit protection.
In general, a grounding-type instrument transformer used for electrical equipment of 66 kV or higher is arranged coaxially with a primary winding and a secondary winding in which an electric wire is wound in a multilayer cylindrical shape with an interlayer insulating paper interposed therebetween, A bipodal iron core is assembled to the central axis of the cylinder, and a bushing and a secondary terminal box are provided, and the cylinder is housed in a sealed container filled with an insulating gas such as SF ₆ gas.
[0003]
Here, the primary winding of a grounding-type instrument transformer must be wound in a multi-layered cylindrical shape with the same winding width from the beginning of winding to the end of winding. Therefore, the entire coil is molded with an epoxy resin or the like, and the interlayer insulating paper and the electric wire are fixed with an adhesive tape or an 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. A structure in which the paper 11 is fixed with an adhesive 15 is shown.
[0004]
As is well known, when a steep voltage (lightning impulse waveform) is applied to the winding of a grounded instrument transformer from the bus side, the voltage applied per winding layer is not uniform as shown in FIG. In addition, it is known that the pressure increases as the pressure increases. For this reason, it is necessary to increase the strength of the interlayer insulation at the high voltage end compared to the low voltage side. Therefore, as shown in FIG. 10, the number of turns per layer of the primary side winding may be decreased stepwise as the winding proceeds to the high voltage side. Further, FIG. 11 shows the winding with the same number of windings on the low pressure side in accordance with the allowable number of windings at the highest pressure end.
[0005]
[Problems to be solved by the invention]
However, as described above, large-scale casting equipment is required to resin-mold the windings, and if large-sized windings such as the windings of transformers for ultra-high voltage instruments are to be resin-molded, voids can be prevented. Therefore, advanced casting technology is required. Moreover, in the structure which fixes the interlayer insulation paper 2 and the electric wire 1 with the adhesive tape 4, there existed a problem that the adhesive strength fell with heat and the intensity | strength with respect to an impact fell.
[0006]
Further, in the structure in which the interphase insulating paper 11 and the electric wire 12 are fixed with the adhesive 15, an extra process for heating and curing after the end of the winding is necessary, or because the coating amount of the adhesive 15 varies, the coil There are drawbacks such as non-uniformity of the size and partial discharge due to the formation of minute voids. As a countermeasure against steep voltages, when the method as shown in FIG. 10 is adopted, several kinds of jigs for adjusting the position of the winding are prepared, and there is a troublesome use of a special winding machine. When such a method is adopted, there is a problem that the outer dimension of the winding is increased.
[0007]
[Means for Solving the Problems]
Therefore, in order to solve the above-mentioned problems, the present invention provides a primary winding and a secondary winding in which an electric wire is wound in a multilayer cylindrical shape with an interlayer insulating paper interposed therebetween, and is coaxially arranged, and a biped on the axis. In a grounded instrument transformer with an iron core,
An interlayer insulating paper for the primary winding to form a cross Menhe shaped protrusions at both ends,
The axial length is the same from the innermost winding layer to the outermost layer and is wound around the interlayer insulating paper, and the wire for the primary winding in which the wire diameter is gradually increased from the innermost layer to the outermost layer,
A fastening band that is attached between the outermost layer of the primary winding and the electric field relaxation shield, and tightens and holds the primary winding;
It is provided with.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view in which a part of a grounded-type instrument transformer according to the present invention is broken, 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 that is a shield for electric field relaxation, 4 is a ground shield, and 5 is a frame that constitutes a leg portion of a two-legged iron core.
[0009]
FIG. 3 is an external view of the winding 2 taken out 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, and 9 is a primary winding 8. It is a tightening band wound around the outside. By fastening both ends of the fastening band 9 with the bolts 10, the fastening band 9 fastens and holds the primary winding 8 with a predetermined tension.
[0010]
4 is an enlarged cross-sectional view showing a part of the primary winding 8 and the fastening band 9 of FIG. In the drawing, reference numeral 11 denotes an interlayer insulating paper, and both end portions in the axial direction are bent into a cross-sectional shape to form a convex portion 11a. This convex part 11a becomes a guide when winding the electric wire 12, and a drop in the middle of the winding is prevented, and the workability of the winding work is improved.
[0011]
Further, the outer side of the outermost interlayer insulating paper 11 is fastened by the fastening band 9, so that the convex portions 11a are brought into contact with each other in the thickness direction, and the interlayer insulating paper 11 is stably held against the impact in the axial direction. Is done. Further, the primary winding 8 is composed only of the interlayer insulating paper 11 and the electric wire 12, and the winding can be made with a uniform thickness by not interposing other adhesives or the like, and a material having a high dielectric constant such as an adhesive is used. By not interposing, the probability of occurrence of partial discharge is also reduced.
[0012]
FIG. 5 is a cross-sectional view showing the total thickness of the primary winding 8. As shown in the figure, the electric wire 12 constituting the primary winding 8 has three types of thickness, the thinnest electric wire 12A is wound on the inner side, the outer side is wound with an intermediate thickness electric wire 12B, and the outer side thereof is wound. Is wound with the same length from the innermost layer of the winding to the outermost layer. Thus, the number of turns is reduced by gradually increasing the diameter of the electric wire 12 of the primary winding 8 from the low voltage side (inner side) to the high voltage side (outer side). Such a voltage can be lowered stepwise.
[0013]
Moreover, since the electric wire diameter becomes thicker as it rolls outward, the interlayer electric field at the high voltage end is also synergistically reduced, and the insulation strength is strengthened compared to the low voltage side. Further, since the low voltage side can be wound until the interlayer voltage reaches the allowable value, 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. Furthermore, since only the electric wires having different diameters are wound in order for manufacturing, no special jig or winding machine is required in the process. In the embodiment, the diameter of the electric wire 12 is three types, but it is possible to further reduce the diameter to four or more types.
[0014]
【The invention's effect】
As described above, according to the present invention, the convex portions are formed at both ends of the interlayer insulating paper, so that the winding is prevented from being displaced or broken, and the winding work is facilitated. Further, by increasing the diameter of the wire stepwise, the voltage applied per contact is lowered stepwise, and the insulation strength is strengthened compared to the low voltage side by reducing the interlayer electric field at the high voltage end. Further, by tightening the outermost layer of the primary winding with a tightening band, the convex portions of the primary winding interlayer insulating paper are held in contact with each other in the vertical direction, thereby stabilizing against the impact in the axial direction.
[Brief description of the drawings]
FIG. 1 is a front view of a grounded instrument transformer according to the present invention, partly broken away.
FIG. 2 is a side view of FIG.
FIG. 3 is an external view showing a winding portion extracted from FIG. 1;
4 is an enlarged cross-sectional view showing a part of the primary winding and the fastening band of FIG. 3;
FIG. 5 is a cross-sectional view showing the total thickness of the primary winding.
FIG. 6 is a cross-sectional view showing a conventional example.
FIG. 7 is a cross-sectional view showing a conventional example.
FIG. 8 is a cross-sectional view showing a conventional example.
FIG. 9 is a graph showing the relationship between the number of turns and the potential.
FIG. 10 is a cross-sectional view showing a conventional example.
FIG. 11 is a cross-sectional view showing a conventional example.
[Explanation 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 Protrusions 12, 12A, 12B, 12C

Claims (1)

In a grounded instrument transformer in which a primary winding and a secondary winding in which an electric wire is wound in a multilayer cylindrical shape with an interlayer insulating paper interposed therebetween are arranged coaxially, and a two-legged iron core is assembled to the axis.
An interlayer insulating paper for the primary winding to form a cross Menhe shaped protrusions at both ends,
The axial length is the same from the innermost winding layer to the outermost layer and is wound around the interlayer insulating paper, and the wire for the primary winding in which the wire diameter is gradually increased from the innermost layer to the outermost layer,
A tightening band that is mounted between the outermost layer of the primary winding and the electric field relaxation shield and tightens and holds the primary winding;
A grounding-type instrument transformer characterized by comprising:

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