JPH0360168B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a converter for changing the taps of a transformer, and particularly relates to a converter for changing the taps of a transformer applied to high voltage. .

[Conventional technology]

1 and 2 show an example of a conventional tap-switching converter (hereinafter simply referred to as a converter) of a transformer. In the figure, the three phases of a transformer having a λ-connection transposed switching winding are assumed to be a phase, b phase, and c phase, and in the figure, subscripts a, b, and c correspond to each phase. Loose tap windings 1a, 1b, 1c for transposition switching
(1c is not shown) is the tap on the side to be switched,
The close tap windings 2a, 2b, 2c are provided with an appropriate number of taps and switching sides. Winding 1
Although c and 2c are omitted, they are the same as the a and b phases. 3a, 3b, and 3c indicate tap selection states, and the figure shows a state in which the lowest limit tap is grasped. The (tap) fixed contacts 4a, 4b, 4c of the converter are connected to the connection leads 7a, 7b,
7c, which are connected to the windings of each phase, respectively, and fixed contacts 5a, 7c of the converter.
5b and 5c are connected to the taps of the windings of each phase by connection leads 8a, 8b, and 8c, respectively,
Converter (tap) fixed contacts 6a, 6
b, 6c are connected to the taps of the windings of each phase by connection leads 9a, 9b, 9c, respectively. Further, fixed contacts 4a to 4c and fixed contacts 5a to 5c, 6a to 6c arranged in series parallel to the fixed contacts 4a to 4c are sequentially mounted in the axial direction together with the terminal shield 11 on the inner circumferential wall of the insulating tube 10 having a hollow cylinder shape. The insulating cylinder 10 is fixed by the upper frame 12 and the lower frame 13. Therefore, the fixed contact is formed in an arc shape along the inner circumferential wall of the insulating cylinder 10. The fixed contacts 4a...6c are arranged between the upper frame 12 and the lower frame 13, and in the a phase, the a-phase fixed contacts 4a are placed in the first row, and the a-phase fixed contacts 4a are placed in the second row.
Phase and fixed contacts 5a and 6a are arranged in a divided manner in the circumferential direction, and thereafter, b-phase and c-phase fixed contacts are similarly arranged in sequence. The movable contacts 14a, 14b, and 14c of each phase are supported by an arm shaft 15 that rotates about the central axis 15a of the insulating cylinder 10. The structure of the arm shaft 15 will be omitted. Further, the upper and lower frames 12 and 13 are set to a neutral point potential through connection leads 16 and 17. Therefore, the voltages generated at each part of the converter in the arrangement and configuration shown in the figure are as follows. Loose tap windings 1a to 1c and dense tap windings 2a
It is customary for the windings of ~2c to be approximately equal, and the voltage generated per winding can be considered to be approximately the same. The contact 6a and the a-phase, between the fixed contacts 5a and 6a, and between the lower frame 13 and the c-phase fixed contact 6c are each one winding,
There are two windings between the a-phase fixed contact 6a and the b-phase fixed contact 4b and between the c-phase fixed contact 5c and the lower frame 13, and three windings between the a-phase fixed contact 5a and the b-phase fixed contact 4b. . Here, 2 windings is the sum of the close tap winding 2a and the close tap winding 2b, and 3 windings is the sum of the above 2 windings plus the sparse tap winding 1a. Show what you have. In addition, since the voltages generated at the locations other than those described above will be any of the above, explanations will be omitted.

The converter configured as described above becomes either connected or connected by moving the movable contacts 14a to 14c. That is, in FIG. 1, the movable contacts 14a to 1
4c is inserted into the fixed contacts 6a to 6c, and are connected to each other. Now, when the movable contacts 14a to 14c are driven by the arm shaft 15, moved to the left in FIG. 1, and inserted into the fixed contacts 5a to 5c, they are connected. Note that this switching is normally performed in a no-load state or a state equivalent to no-load state.

However, the conventional device as described above has the following problems.

(1) The voltage generated at each part is the fixed contact, other phase fixed contacts 5a and 4b, 5b and 4c.
Except for 1 to 2 windings, other phase fixed contacts 5a, 4b, 5b of fixed contacts
Since the space between and 4c is for three windings, it takes time to design and check the withstand voltage. In particular, the higher the voltage, the greater the effect.

(2) In addition, when attempting to upgrade the withstand voltage rating of existing products, methods of mitigating the electric field by extending the insulation distance and installing a shield are used, but in the conventional arrangement, fixed contacts 5a to 5c have different potentials. 6a-6c are adjacent, making it difficult to design an effective shield. In addition, increasing the distance is not a very good idea, especially in the case of gas insulating media. Therefore, it is difficult to increase the voltage.

[Summary of the invention]

This invention attempts to solve the above-mentioned drawbacks of the conventional device, and has a configuration in which a fixed contact is sandwiched between the fixed contact and a dummy contact corresponding to one of the fixed contacts is arranged in parallel. To provide a converter for tap switching of a transformer, which can suppress the generated voltage to less than two windings, and can easily be applied to high voltages by attaching a shield.

[Embodiments of the invention]

FIG. 3 and FIG. 4 show an embodiment of the present invention, and show fixed contacts 4a, 4b, 4c.
Fixed contacts 5a to 5c, 6a are provided between
Dummy contacts 18a, 18b, and 18c, which are equivalent to fixed contacts, are arranged in parallel with the contacts 18a, 18b, and 18c sandwiching the contacts 18a, 18b, and 18c, respectively.

With the above configuration, it can be easily understood that the voltage generated in each part is equal to one to two windings. This is true regardless of the connection state of the tap connections 3a to 3c and the converter. Furthermore, the location where the two windings are generated is only between the fixed contacts including the dummy contacts, and the arrangement and structure make it easier to attach a shield for electric field mitigation compared to the case of the fixed contacts 5a to 5c.

5 and 6 show other embodiments, dummy contacts 19a, 19 having the same shape as the fixed contacts 4a, 4b, 4c and having only a potential.
b and 19c are arranged side by side, and similar effects can be expected. The dummy contacts 19a to 19c and the fixed contacts are connected through potential determining leads 20a, 20b, and 20c, respectively.
The rest is the same as FIG. 3 and FIG. 4, so the explanation will be omitted.

In the above two embodiments, the same dummy contacts as the fixed contacts are used as the dummy contacts, but the dummy contacts are not limited to this, and it goes without saying that any suitable shape may be used.

By the way, in the above embodiment, a three-phase case was explained, but in general, even if it is an N-phase (including a single phase),
It is easy to understand that similar effects can be expected.

〔Effect of the invention〕

As explained above, in this invention, by arranging the dummy contacts in parallel between the fixed contacts and the fixed contacts, the generated voltage is equal to at most two windings, and moreover, the maximum voltage is This is effective when a high withstand voltage is required, and the effect is particularly great as it makes it easy to upgrade the withstand voltage of existing products.

[Brief explanation of drawings]

FIG. 1 is a front view of the conventional device, FIG. 2 is a sectional view taken along the - line in FIG. 1, FIG. 3 is a front view of an embodiment of the present invention, and FIG. −
5 is a front view of another embodiment of the present invention, and FIG. 6 is a sectional view taken along the line - in FIG. 5. 4a, 4b, 4c... fixed contact, 5
a, 5b, 5c... Fixed contact, 6a, 6
b, 6c... Fixed contact, 10... Insulating tube, 11... Terminal shield, 14a, 14
b, 14c...Movable contact, 15...Arm shaft, 18a, 18b, 18c, 19a, 19b,
19c...Dummy contact. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A cut-out cylindrical insulating tube, a fixed contact on the switching side disposed along the circumferential direction on the inner circumferential wall of the insulating tube, and a switching target divided and disposed parallel to the contact. A tap switching converter for a transformer comprising a side fixed contact, a fixed contact, and a movable contact that is rotationally displaced about the central axis of the insulating cylinder, wherein the fixed contact is sandwiched between the fixed contact and the fixed contact. A converter for tap switching of a transformer, comprising a dummy contact arranged in parallel with the fixed contacts and having the same potential as one of the fixed contacts. 2. The tap switching converter for a transformer according to claim 1, wherein the transformer is a multi-phase transformer.