JP2556104B2 - Current transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of a current transformer, in which an insulating transformer is integrated with the current transformer so that an abnormality on the high voltage side can be detected from the low voltage side. It is a thing.

[Conventional technology]

2 (a) and 2 (b) are a front sectional view and a partial sectional side view showing an example of a conventional current transformer, in which the primary winding 1 is covered with an insulating layer 2 and the primary terminals 3 (K, L). ) Is connected, and the secondary winding 5 is wound around the entire circumference of the iron core 4 which is linked to this, and the secondary terminal 6 (k, l) is connected. The current transformer is housed in a container such as a porcelain tube, filled with an insulating gas or an insulating material (not shown) such as a molding agent, and the insulating layer 2 together with the primary winding 1 and the secondary winding. Insulates between 5.

On the other hand, it is known to use an insulating transformer for supplying power from the low voltage side to the high voltage side, transmitting high voltage side information to the low voltage side, and preventing other high voltage from entering the low voltage circuit. That is, for example, as an example of high-voltage side information, a contact is provided directly for abnormal expansion of the oil quantity regulator of the current transformer provided for measuring the high-voltage side current, overheating of the primary terminal of the current transformer, or the like. Can be detected, or the contact can be operated via a bimetal, and the result can be detected on the low voltage side through an isolation transformer.

[Problems to be Solved by the Invention]

As this type of insulation transformer, conventionally, a dedicated insulation transformer is provided separately from the current transformer, and especially when the high-voltage side has a large voltage, a large-sized insulation transformer is required in addition to the current transformer. The drawback of doing was unavoidable.

[Means for solving the problem]

In order to solve the above-mentioned drawbacks, the present invention incorporates an insulation transformer into a current transformer, and changes the structure of a structure in which the insulation of the primary winding of the current transformer is shared by the high-voltage side winding of the insulation transformer. The present invention provides a current transformer having the basic structure of the current transformer shown in FIG. 2 and an insulating transformer integrally provided on the primary winding thereof.

〔Example〕

FIG. 1 (a) is a partially sectional front view showing an embodiment of the present invention, and FIG. 1 (b) is a partially sectional side view. Here, as is apparent from FIG. 1 (b), the primary core 1 of the current transformer is provided with the iron core 11 for the insulating transformer, which is provided with the high-voltage side winding 10 all around in advance.
Is integrally provided along with, and the high voltage side terminal 12 is connected to the high voltage side winding 10.

Next, the primary winding 1 of the current transformer and the high voltage side winding
The insulating transformer iron core 11 provided with 10 is integrated to form the insulating layer 13, and the winding on the low-voltage side 14 of the insulating transformer is provided all around the insulating layer 13.
Is provided and the low voltage side terminal 15 is connected. Further, an iron core 4 for a current transformer and a secondary winding 16 for a current transformer wound around the entire circumference thereof are provided so as to be linked to the insulation transformer.

Here, the secondary winding 16 of the current transformer and the high-voltage side winding 10 and the low-voltage side winding 14 of the insulation transformer are so-called Rogowski coil-shaped windings, each of which is folded back along the winding from the end of winding, By pulling out from the vicinity of the winding start end, the effect of one turn due to the toroidal winding wound around the iron core is canceled and there is no risk of causing errors in the characteristics of the insulating transformer and the current transformer.

The Rogowski coil structure is shown in Fig. 1 (a).
Is shown on the low voltage side winding 14 of the isolation transformer, on the same side (b) to the current transformer secondary winding 16, and on the high voltage side winding 10 of the isolation transformer in the same (c) described later.

Further, in the present embodiment, as described above, as one of the uses of the insulating transformer, it is assumed that the high-voltage side information of the current transformer is detected on the high-voltage side via a contact or the like and is detected on the low-voltage side. Therefore, the power is supplied from the terminal 15 of the isolation transformer through the low voltage side winding 14. Therefore, in the insulation transformer, the low voltage side terminal 15 is the primary side, that is, U, V, and the high voltage side terminal 12 is the secondary side, that is, u, v.

On the other hand, the iron core 11 of the insulating transformer is linked to the iron core 4 of the current transformer, and if a one-turn circuit is formed through the iron core 11, the characteristics of the current transformer are affected. For this reason, as shown in FIG. 1 (c), the air gap 17 is provided in the iron core 11 of the insulation transformer.
Make sure 11 does not form a turn.
Of course, the iron core 11 may have a divided structure in which voids are provided at two places.

Further, as shown in FIG. 3, the insulating transformer iron core 11 is formed by winding a continuous iron core piece 18 with an insulating tape 19 made of, for example, PET (polyethylene terephthalate) film or the like, or as shown in FIG. As described above, the insulating tape 19 may be superposed on the iron core piece 18 and wound up to form a wound iron core which eliminates the fear of forming one turn.

Since the iron core 5 of the current transformer is linked with the iron core 11 for the insulating transformer as described above, the characteristics of the insulating transformer may be affected if the iron core 5 of the current transformer also has one turn. However, when a silicon steel plate, which is a usual iron core material, is used for the iron core 5 of the current transformer, an oxide film is formed on the surface by the annealing treatment, so that one turn is formed through the high resistance,
There is no problem unless the insulation transformer requires a high degree of error characteristics.

However, especially when the iron core 1 of the current transformer is large, or when there are multiple iron cores, one turn formed in the current transformer core by using a special iron core is one turn through high resistance. When the circuit disappears and becomes a problem due to the characteristics of the insulating transformer, the wound core structure may be insulated by the insulating tape 19 shown in FIGS. 3 and 4 in the same manner as the insulating transformer core. . Also, if there is no problem in the error characteristic of the insulation transformer, a cut core can be used.

〔The invention's effect〕

As described above, according to the present invention, the primary side insulation layer of the current transformer is attached to the insulation transformer by attaching the iron core and the high-voltage side winding of the insulation transformer along the primary winding of the current transformer. It can be shared with the high voltage side winding and can be made smaller.

[Brief description of drawings]

1 (a) and 1 (b) are a partial cross-sectional front view and a partial cross-sectional side view showing an embodiment of the present invention, and FIG. 1 (c) is an insulating transformer iron core in which a void is provided in a part thereof. FIGS. 2 (a) and 2 (b) are front sectional views and partial sectional side views showing an example of a conventional current transformer, FIGS. 3 and 4 are explanatory views showing a state in which formation of turns is prevented. It is an explanatory view showing the state where it insulates with an insulating tape to each iron core piece, and it makes it a winding iron core. 1 ... Primary winding, 2 ... Insulation layer, 4 ... Current transformer core, 5
…… Secondary winding, 10 …… High voltage side winding, 11 …… Insulation transformer core, 14 …… Low voltage side winding.

Claims (1)

(57) [Claims] 1. A current transformer in which a secondary winding is wound around an iron core for a current transformer which is linked to a primary winding over substantially the entire circumference of the iron core, and a high voltage side winding is wound around the entire circumference. An insulating transformer iron core provided along the primary winding, an insulating layer integrally covering the primary winding and the insulating transformer iron core, and a low-voltage side winding provided almost all around the insulating layer. An insulation transformer is constituted by the insulation transformer iron core and the high-voltage side winding and the low-voltage side winding, and the insulation transformer iron core has a structure that prevents a short circuit around the iron core, and the secondary winding. A current transformer characterized in that the wire and the high-voltage side winding and the low-voltage side winding have a Rogowski coil structure.