JPH02238609A - End part of coil - Google Patents

Abstract

PURPOSE:To increase a creeping resistance from a conductor exposed on an insulating coating or from a lead wire connected to the conductor to a coil on an iron core by a method wherein a first insulating layer and a second insulating layer which wrap the conductor and the insulating coating and whose electrical insulating property is high are formed on the conductor and on the insulating coating covering the conductor. CONSTITUTION:First insulating layers 13 formed by impregnating a felt with a resin and by solidifying it are formed on insulating coatings 7 with which conductors 8 of coil ends 3, 4 are covered are formed; second insulating layers 14 which have been insulation-treated with a resin are formed so as to wrap the insulating coatings 7 connected to them and end parts of the conductors 8 are formed. Thereby, parts from the conductors 8 exposed on the insulating coatings 7 of the coil ends 3, 4 to the surface of a coil 2 are insulation-treated by using the first insulating layers 13 and the second insulating layers 14; a creeping resistance against a flashover current can be made sufficiently large; it is possible to surely suppress a creeping breakdown from the conductors 8 to an iron core and to prevent a dielectric breakdown of adjacent coils.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a coil that prevents creepage flashover from occurring from the coil end to the coil surface when conducting a dielectric breakdown test of a coil wound around an iron core. It concerns the ends.

[Conventional technology]

Fig. 2 is a schematic diagram showing the conventional dielectric breakdown test method for coils. In the figure, 1 is an iron core at ground potential, and 2 is a coil whose coil side part is inserted into a groove 1a cut in the iron core 1. , 3 and 4 are the coil ends at the beginning and end of winding, and 5 is a high voltage power supply, one end of which is connected to the conductor at the end of the coil at the beginning of winding.
The other end is grounded.

FIG. 3 shows details of each of the coil ends 3, 4, each of which has an insulating coating 7 on the conductor 8, except for a portion thereof.
It is configured with

Next, the operation will be explained.

When conducting the dielectric breakdown test of coil 2, the second
In the arrangement of the coil 2 as shown in the figure, the high voltage power supply 5
A high voltage is applied to the conductor 8 at the end of the coil at the beginning of winding while increasing the voltage. When this high voltage reaches a set value, current suddenly begins to flow, breaking the coil's insulation. Therefore,
By observing the timing at which this current suddenly begins to flow, it is possible to test the dielectric strength of the coil.

[Problem to be solved by the invention]

The conventional coil insulation testing method is as described above.
If a part of the conductor 8 at the end of the coil to be tested is exposed as shown in Figure 3, and the surface of the coil 2 is damp or dirty, the coil 2 can be removed from the exposed part of the conductor 8. In addition to causing mechanical damage (flash m) to the iron core 1 through the surface, the coil near the exposed part was destroyed, making it impossible to accurately measure the dielectric breakdown value of the coil.

This invention was made in order to solve the above-mentioned problems, and it provides an insulation treatment structure that prevents creepage breakdown from the conductor at the end of the coil to the core and allows measurement of the true dielectric breakdown value of the coil on the core. The aim is to obtain a coil end with

[Means to solve the problem]

In the coil end according to the present invention, a first insulating layer made of felt impregnated with resin is provided on the insulating sheath covering the conductor at the end of the coil, and the first insulating layer is continuously connected to the insulating sheath and the conductor. A second insulating layer, which is insulated with resin, is provided so as to wrap around the ends of the insulating layer.

[Effect]

The first insulating layer and the second insulating layer in this invention are
In order to sufficiently insulate the conductor exposed from the insulation coating at the end of the coil to the surface of the coil and sufficiently increase the creepage resistance against flash final current, it is possible to reliably suppress creepage damage from the conductor to the core, and to It also acts to prevent dielectric breakdown of the coil.

[Embodiments of the invention]

Hereinafter, a practical example of this invention will be explained with reference to the drawings. 1st
In the figure, 11 is a lead wire connected to the end of the conductor 8 at the end of the coil at the beginning of winding, and 12 is a tube of polyester film, which is fitted into the insulation coating 7 so as to surround the conductor 8 and the lead wire ]-1. 13 is the tube 1 fitted in this way
The first insulating layer tightly closes the gap between the end of the insulation coating 7 and the insulating coating 7, especially the gap in a complex shape part, and is made by impregnating felt such as polyester felt with a resin such as room temperature curing epoxy resin. consists of things. Reference numeral 14 denotes a second insulating layer, which is provided continuously on the first insulating layer Ml3, and is formed into a cylinder so as to cover the insulating coating 7, all of the conductor 8, and a part of the lead wire 11 with a sufficient thickness. , 2 is filled in. Further, this second insulating layer 14 is made of room temperature curable epoxy resin. Note that no lead wire is provided at the coil end 4 at the end of winding. This is because the conductors 8 at the coil ends 3 and 4 at the beginning and end of winding are connected to the same potential through the coil part conductor, and can be omitted.

Next, the operation will be explained.

First, as described above, the high voltage power supply 5 is connected to the lead wire 11, and a high voltage is applied to the coil 2 by gradually increasing the voltage. When the insulation of the coil 2 breaks down, Measure the current change and perform a dielectric breakdown test. In this case, since a part of the exposed conductor 8 and lead wire 11 is covered with the first and second insulating layers 13.14, the conductor 8 and lead wire 11 and the coil on the iron core 1 are
Because the creepage distance between the coil 2 and the coil 2 is sufficiently long and the insulation structure is dense, even if the surface of the coil 2 is damp or dirty, the insulation resistance to ground is sufficiently high and the coil 2 No flashover occurs through the surface of 2.
There is no room for creepage failure as described above to occur.

However, the tube 12 is omitted, and the second insulating layer 14 is made continuous with the first insulating layer 13 by brushing a varnished glass bias tape with a room temperature curing epoxy resin. , may be wound. In this case as well, the room-curing epoxy resin functions to closely insulate the layers of the tape. For example, coil 2 with a rated voltage of 6KV
Now, a varnished glass bias tape with a thickness of 0.15++WI+ is wound six and a half times. In this way, even in the embodiment using the varnished glass bias tape, the same effects as in the above embodiment can be achieved.

In addition, although the lead wire 11 is made of bare copper wire in the embodiment, if a coated copper wire is used, the prevention of creeping damage can be further improved.

〔Effect of the invention〕

As described above, according to the present invention, the first and second insulating layers with high electrical insulation properties are provided on the conductor and the insulating coating covering the conductor. The creepage resistance from the conductor connected to the conductor and the lead wire connected to this conductor to the coil on the core can be made sufficiently large, so that the high voltage applied to the conductor during the dielectric breakdown test of the coil can be applied to the core. This has the effect that it is possible to suppress flashovers in the opposite direction, and it is possible to measure the true value of the dielectric breakdown value.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts showing the insulation treatment structure of the coil end according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing the conventional method for dielectric breakdown testing of a coil, and Fig. 3 is a sectional view of the main part showing the insulation treatment structure of the coil end according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the coil end structure of FIG. 2 is a coil, 3 and 4 are coil ends, 7 is an insulating coating, 8 is a conductor, 13 is a first insulating layer, and 14 is a second insulating layer. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Mitsubishi Electric Corporation

Claims (1)

[Claims] a coil end with an insulating coating on the conductor except for the end of the conductor;
A first insulating layer made of felt impregnated with resin and hardened is attached to the insulating coating at the end of the coil, and the first insulating layer is continuously attached to the insulating coating and the end of the conductor. The coil end portion is provided with a second insulating layer subjected to insulation treatment using resin.