JPS5940282B2 - On-load tap changer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a vacuum switch type changeover switch placed in the center inside the tap selector, and the changeover switch and tap selector, which are at the same potential for each phase, are arranged in one plane. ] Regarding the tap changer installed.

It is well known that an excellent on-load tap changer with extremely high performance can be realized by using a vacuum switch as the current switching element of the on-load tap changer.

However, current vacuum switches have the disadvantage of insufficient shock-resistant voltage characteristics to be applied to on-load tap changers. Therefore, it is necessary to ensure that the voltage between the taps is not applied to the vacuum switch at all times. The present invention relates to a method of configuring a load-time tarp switch using a resistive parallel division method in order to solve the above-mentioned difficulties.
Resistive parallel segmented tap switching systems have often been employed in on-load tap changers of the so-called load tap selector system, which allows arcs to be cut off at the tap selector section.

Conventional load tap selector type on-load tap changers generate arcs in the tap selector section and contaminate the surrounding oil.
The fixed contacts of the tap selector are arranged radially on the inner surface of the insulating cylinder, which is completely separated from the oil chamber of the transformer body, and the movable contacts connect adjacent fixed contacts with a resistor, reactor, etc. A method has been adopted in which the tap is bridged through a current-limiting impedance, and then the tap that is hot during operation is opened. Such a conventional load tap selector system has the following drawbacks. (a) The fixed contacts of the tap selector are attached to the inner surface of the insulating cylinder, and arcs are generated in this part, so there is a risk of dielectric breakdown between the fixed contacts via the creeping surface of the insulating cylinder, so the voltage is too high. cannot be used for

(b) Since the engaging parts of the movable and fixed contacts of the tap selector are enclosed in an insulated cylinder, it is almost impossible to visually inspect and adjust the engagement status of these when assembling the on-load tap changer. Since it is possible, we will take it in terms of reliability.

The drawback of (a) above can be solved to some extent by simply replacing the current switching contact with a vacuum switch using the conventional method.
764.

However, even with this method, the fixed contact of the tap selector is still attached to the inner surface of the insulating cylinder, so the insulation reliability is improved and the vacuum switch part that switches on and off the current is connected to the oil in the transformer body. The structure does not allow for easy maintenance and management, which is essential for practical use, such as easy inspection without removing the taps.The present invention has a structure in which the fixed contacts of the tap selector are configured by a combination of a conventional tap selector and a switching switch. Similar to the on-load tap changer, it is fixed on an insulating bar to ensure insulation between adjacent fixed contacts between the insulating oil chambers, and one of the movable contacts of the tap selector. The disadvantages of the conventional methods are solved by driving the tap selector with an insulating tube located centrally inside the tap selector and housing a current-switching element in the insulating tube.

FIG. 1 is a diagram showing the operating principle of an embodiment of the on-load tap changer according to the present invention.

In Fig. 1, 1 is a part of the tap winding of a transformer, etc., 2 is the fixed contact of the tap selector, 3 is the tap selector fixed contact connected to the tap adjacent to 2, and TSM is the main contact tap. Selector movable contact, TSR is the tap selector movable contact for resistance contact, VSM is a vacuum switch, VSR is a vacuum switch connected to TSR via current limiting resistor R, 4 is the output terminal of the tap changer on load. be. The above circuit configuration is
It is a known circuit except that a current switching element is inserted in series with the TSM and TSR, and the switching operation order from tap to tap 3 shown in Fig. 1 and each contact shown in Fig. 2 are known. The operating principle can be easily inferred from the sequence diagram showing the opening/closing order, so it will be omitted. FIG. 3 shows an embodiment of the configuration of the on-load tap changer according to the present invention. In FIG. 3, the same numbers or symbols as in FIG. 1 indicate the same or equivalent parts. In the figure, 5 is a switching switch that includes a current switching element such as a vacuum switch, a current limiting resistor, and a connection terminal to an external circuit, and 6 is a switching switch that houses the switching switch 5 and keeps the space where the tap selector is placed oil-tight. An insulating tube made of the same cylindrical insulating material as a shield. Insulating cylinder 6
Tap selector movable contacts TSM and TSR are fixed to the outer periphery of the tap selector. 7 is an insulating rod for fixing the fixed contact of the tap selector, and in a three-phase on-load tap changer, each phase tap lead corresponding to the same number is connected and engaged with the movable contact of each phase tap selector. Fixed contacts 2, 3, etc. of the tap selector are arranged vertically with interphase insulation.

Tap selector fixed contact width and tap selector movable contact T
The angles of the SM and TSR are configured so that the sequence shown in FIG. 1 can be realized. 8 is the main contact tap selector TS
Fixed point M, 9 is the movable contact TS of the tap selector for resistance contact.
It is a fixed point of R.

10 is a conductive ring for the main contact, and 11 is a current collecting ring for the resistance contact, which are fixed to the inner surface of the switching switch chamber 6.

Fixing points 8 and 9 of the movable contacts of the tap selector pass through the insulating tube 6 in an oil-tight manner and are electrically connected to the current collecting rings 10 and 11, respectively, on the inner surface of the insulating tube. 12 and 13
are connection contacts that project in the radial direction from a member fixed in the structure of the switching switch using a push spring or the like and are configured to contact the current collecting rings 10 and 11, respectively.

The main contact connection point 12 is connected to the fixed electrode end of the vacuum switch via a flat striped copper stranded wire or the like having sufficient flexibility to prevent the protrusion movement in the radial direction. The resistance contact connection contact 13 is connected to one end of a current-limiting resistor R fixed to a suitable fixing member of the switching switch via a street conductor, similar to the above-mentioned 12. The other end of the resistor R is connected to a fixed end of a resistor connection vacuum switch VSR. 14 is an insulating plate for fixing the vacuum switches VSM and VSR.

4 is the output terminal of the switching switch as shown in Figure 1, and is a structure made of conductive material with a circular cross section that constitutes the neutral point of the Y-connection transformer, and is fixed to the switching switch. And it is arranged at the center of the insulating cylinder 6.

The movable electrodes 15, 16 of the vacuum switches VSM and SR are connected to the output terminal 4 of the on-load tap changer via a flexible conductor. Reference numeral 17 denotes a cam plate for driving the vacuum switch fixed to the inner surface of the insulating cylinder, and by engaging the cam plate with the vacuum switch movable electrode directly or via a cam follower (not shown), etc.
The vacuum switches VSM and VSR are configured to be opened and closed in a predetermined sequence.

Reference numeral 18 denotes a head case of the on-load tap changer, which is fixed onto a flange 19 provided on the main body of the transformer.

20 is a Geneva pinion driven by an operation mechanism of a load tap changer (not shown), and 24 is a Geneva gear that is intermittently driven by the Geneva pinion.

Reference numeral 22 denotes a metallic circular tube fixed inside the Geneva gear, which is rotatably supported on the load tap changer head case 18 and is connected between the inside of the head case 18 and the tap selector chamber. Oil-tightness is maintained with a sealing device such as an oil seal.

One end of the circular tube 22 is inserted into the insulating tube 6 and fixed. The switching switch 5 is detachably fixed to the load tap switch head case 18. Reference numeral 23 denotes a bottom plate circular tube which is inserted into and fixed in the insulating tube 6 and has an end plate in the middle thereof.

The bottom plate circular tube 23 is rotatably supported by the tap selector bottom metal fitting 28. Reference numeral 24 denotes a relay contact having a circular cross section and made of a conductive material, which is fixedly passed through the center of the end plate portion of the bottom plate circular tube 23 in an oil-tight manner.

Electrical connection is maintained between the on-load tap changer output terminal 4 and the protrusion of the insulating tube of the relay contact 24 by a tube contact 25. Reference numeral 26 denotes a fixed current collecting contact which is a part of the tap selector bottom fitting 28 and has a circular cross section and is provided on the center line of the tap selector, that is, on the center line of the insulating cylinder 6.

The fixed current collector contact 26 and the other end of the relay contact 24 are electrically connected by a tube contact 27. 30 is a neutral point connecting conductor of the transformer drawn out from one end of the fixed collector contact 26, and is directly grounded, high resistance grounded, etc. according to the system grounding method.

Next, the tap switching method according to this method will be explained.

At the time of tap switching, an operating torque is transmitted from an operating mechanism of a load tap changer (not shown) to rotate the Geneva pinion 20. Geneva pinion 20 connects Geneva gear 21 to 1
Rotate by the angle required to change the tap. The Geneva gear rotates the insulating tube 6 via the cylinder 22, and the tap selector movable contacts TSM and TSR fixed to the insulating tube 6 similarly rotate by an angle necessary for one tap switching. The dimensions of the fixed contacts 2 and 3 of the tap selector, the dimensions between the fixed contacts, and the dimensions of the contact portion of the movable contacts TSM and TSR of the tap selector are configured to satisfy the sequence of the tap selector shown in Fig. 2. There is. The vacuum switches VSM and SR are driven by 17 fixed to the insulating tube 6 in synchronization with the operation of the tap selector so as to satisfy the sequence shown in FIG.
The load current of the transformer is determined by the tap selector movable contact TSM, connection point 12, vacuum switch VSM, output terminal 4 from the fixed contact.
, the tube contact 25, the relay contact 24, the tube contact 27, the current collection fixed contact 26, and the neutral point connection conductor 30. The effects of the present invention can be summarized as follows. 1 The tap selector and the current shearing element are separated, and the fixed contact of the tap selector is fixed on the insulating rod, so the insulation dimension can be determined by the oil-immersed gap, and the tap selector can be easily operated under load. It is now possible to visually inspect the engagement status of the movable and fixed contacts of the assembled tap selector, improving reliability.

Since the insulating cylinder placed in the center of the two-tap selector drives the tap selector and the current cutting element at the same time, the structure is simple and the mechanical reciprocity of both is reliable. As a result, reliability has improved.

3.The insulating tube has an oil-tight structure and the current switching element, that is, the switching switch, is housed in it, so the current loops and breaks, which most often need to be inspected, can be inspected at any time without draining the oil from the transformer body. Now I can do it.

Since the output terminal, that is, the neutral point terminal of the four-way switch is drawn out from the center of the rotating insulating tube, there is no need for a current collector ring and its contacts, which were conventionally required in this type of structure.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the tap switching sequence in one embodiment of the present invention, FIG. 2 is a diagram showing the tap switching sequence in FIG. 1, and FIG. It is a concrete block diagram.

Claims (1)

[Claims] 1. an insulating cylinder rotatably arranged at the center of the tap selector; at least a pair of tap selection movable contacts fixed to the insulating cylinder and controlled to open and close by rotation of the insulating cylinder; A cam plate for driving a current switching element is fixed to the inner surface of the insulating cylinder, and the inner surface of the insulating cylinder is sealed against a space in which a tap selector is placed, and at least one pair of current switching elements are installed therein. An on-load tap changer characterized by housing.