JPS5918851B2 - Current transformer - Google Patents

Description

[Detailed description of the invention] The present invention relates to a current transformer installed in power equipment.

Gas-insulated power equipment is configured to use an insulating gas with good insulation performance and chemical stability, such as SF6 gas, and to configure the charging part in the atmosphere of the above-mentioned insulating gas to achieve miniaturization. . This type of gas-insulated power equipment uses an insulating spacer to insulate and support the conductor, and is bolted to a grounded metal case. An example of this gas-insulated power equipment is one that combines a sealed busbar and an external current transformer, as shown in FIG.

In the figure, the sealed conduit busbar is constructed by connecting containers, that is, metal cases 2 and 3 via an insulating spacer 4, and insulatingly supporting a busbar conductor 5 corresponding to the primary winding on the spacer 4. There is. The external current transformer CT has a structure in which the secondary winding 6 is housed in a metal case T, 8, and is placed outside the bus bar 1 so as to be electromagnetically coupled to the bus conductor 5. This combination of the sealed pipe busbar 1 and the current transformer CT,
Due to electromagnetic induction, a secondary current flows through the secondary winding 6 in inverse proportion to the turns ratio between the primary winding 5 and the secondary winding 6.
The current in the conductor 5 of the bus 1 can be measured by the following current. In addition, when an overcurrent flows through the bus conductor 5, a current transformer, which is the frontmost current detection part of the power protection relay system that should give a shatter breaker command to a shag breaker, etc., detects the current in the bus conductor 5. How accurately the secondary current can be converted into a secondary current with few errors becomes important in terms of protecting the power equipment. Therefore, the current transformer CT
The metal cases 2 and 3 of gas-insulated power equipment are designed to prevent the bus conductor 5 from having an adverse electrical effect on the secondary winding 6 of the gas-insulated power equipment.
In order to cut the electrical closed loop in the space between the spacer and the secondary winding 6, an insulating material X and a CT case
8 must be provided with an insulating material Y to insulate them.

However, in the conventional insulation structure, there was insulation at one location in one closed loop, so it was not easy to verify the insulation of the insulation materials X and Y.

Furthermore, when there are many insulation points, it is troublesome to discover insulation defects. The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a current transformer that allows easy verification of the insulation of the insulation part and is easy to manufacture.

An embodiment of a current transformer according to the present invention shown in the drawings will be described below.

In FIG. 2, the same reference numerals as in the first and second figures indicate the same parts, so the explanation thereof will be omitted. In the present invention, the portion of the sealed conduit busbar 1 to which the current transformer CT is mounted is constructed by connecting metal cases 2, 3, and 9 insulated by insulating spacers 4a, 4b. That is, metal cases 2 and 3
, 9 are insulated by the first insulating material A1 and the second insulating material B1.The second insulating material B1 is always short-circuited with the lead wire 10 to maintain insulation by the first insulating material A1. It's structured. The first insulating material A is also applied to the metal cases 7 and 8 of the current transformer CT.
2 and a second insulating material B2 are provided, and a lead wire 11 is used to constantly short-circuit between them to ground each of the cases 7 and 8, so that insulation is maintained only with the first insulating material A2. . When verifying the insulation of the current transformer of the embodiment configured as described above, as shown in FIG. If a battery E and an ammeter A are connected as electrical continuity means, the insulation can be verified based on the indicated value of the ammeter A. In addition, since the cases 7 and 8 are constructed entirely by providing the first and second insulating materials A2 and B2, the dimensional accuracy at the time of manufacturing the cases 7 and 8 is determined by the first and second insulating materials A2 and B2. This can be covered by A2 and B2, and therefore it becomes possible to easily define the dimensional standards for the entire cases 7 and 8 required for power equipment.

To verify the insulation of the insulated part of the bus bar 1, remove the short-circuit lead wire 10 of the second insulating material B1 and insert the battery E and ammeter A between the metal cases 2 and 3, as shown in FIG. By connecting and conducting an electrical continuity test, the first insulating material A can be easily verified.

As described above, according to the present invention, the secondary winding is housed in a container, and the secondary winding is arranged outside the bus bar of the power equipment so as to be electromagnetically coupled to the bus bar. In terms of the container, the container is divided into two parts, an inner circumferential piece and an outer circumferential piece, and first and second insulating materials are interposed between each divided piece, and the inner circumferential piece and the outer circumferential piece are respectively grounded. 1. When verifying the insulation between the inner and outer circumferential pieces, electrical continuity means is provided between the inner and outer circumferential pieces, making it easy to verify the insulation of the insulating parts. It is possible to provide a current transformer that is easy to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an insulation configuration of a conventional current transformer, and FIG. 2 is a sectional view showing an example of an insulation configuration of a current transformer of the present invention.
3 and 4 are schematic connection diagrams for explaining insulation verification of the same embodiment, respectively. 1... Sealed pipe busbar, 2, 3, 9...
・Bus bar metal case, 4... Insulating spacer, 5.
... Bus conductor, CT ... Current transformer, 7, 8
...Current transformer case, Al, A2...First insulating material, Bl, B2... Second insulating material.

Claims (1)

[Claims] 1. In a current transformer in which a secondary winding is housed in a container and the secondary winding is placed outside the bus bar so as to be electromagnetically coupled to the bus bar of a power device, the container is placed in an inner circumferential part. and an outer circumferential piece, each divided piece is interposed with a first and second insulating material, and the inner circumferential piece and the outer circumferential piece are respectively grounded, and the inner circumferential piece and the outer circumferential part are A current transformer in which electrical continuity means is provided between the inner circumferential piece and the outer circumferential piece when verifying insulation between the inner circumferential piece and the outer circumferential piece.