JPS6352405A - On-load tap changer - Google Patents

Abstract

PURPOSE:To prevent metallic powder from being generated and to improve insulation and reliability, by housing changing switches having mechanical operations into tanks disposed separate from tap winding, high-voltage main winding, and tap selectors and composing the tap selectors of thyristors by which electrical connection and interruption are performed. CONSTITUTION:Changing switches 28 having mechanical operations are housed into tanks disposed separate from tap winding 22 and tap selectors 30, while the tap selectors 30 are composed of thyristors which have no mechanical movements so that electrical switching is performed. Thus, on-load tap changers having no generation of metallic powder can be obtained. Because load current interruption is not performed by the thyristors, lives of the thyristors can be also increased. Because the interruption parts for load switching are disposed in the separate tanks, inspection is facilitated so that metallic powder generated by the mechanical operations can be inspected periodically in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a negative tap changer suitable for a gas insulated transformer.

(Conventional technology) In the unlikely event that a fire or explosion occurs in substations installed in substations or underground substations around large cities,
The impact on society is immeasurable. In particular, there is a high degree of danger in the case of transformers and accelerators that use insulating oil as the insulating medium.Recently, the application of gas-insulated transformers that use nonflammable insulating gas such as SF or gas instead of insulating oil as the insulating medium has been considered. ing. SF insulating oil is used for gas insulated transformers.
Gas PaB transformers with various cooling methods and various improvements have been studied in order to improve the cooling performance from those that have been replaced with gas.

(Problem to be solved by the invention) By the way, the above gas! ! When a TA transformer is used as a power transformer, an on-load tap changer is installed so that the voltage can be adjusted during load depending on load fluctuations, etc.

There are two methods for adjusting voltage during load: a transformer with an on-load tap changer and a transformer with an on-load voltage regulator; in either case, a tap winding and a tap changer are required.

Such a transformer has the following problems.

That is, when using a conventional on-load tap changer, each lead of the tap winding is connected to a tap selector fixed electrode;
A predetermined tap is selected by a movable electrode of a tap selector, and a switching switch is used to cut off the upstream when changing taps. In this case, the fixed main (motorable) 3 electrode contacts each time the tap is switched and is repeatedly opened and closed, resulting in abrasion of the contact or mechanical scratches, which may scatter metal powder into the surrounding insulating medium. do.

As is well known, in gas insulated equipment, if metal powder adheres to the insulating gas or to the surface of fixed insulators, the dielectric strength of the devices will be significantly reduced. Particularly in the case of a gas insulated transformer, if metal powder is scattered, not only the tap changer but also the winding itself will be exposed to the metal powder, which may cause dielectric breakdown of the gas insulated transformer.

An object of the present invention is to provide an on-load tap changer that does not generate metal powder.

[Structure of the invention]

(Means and effects for solving the problem) According to the present invention, a tap selector made up of a plurality of thyristors is housed in the same tank as the tap winding, and a switching switch for cutting off current is installed in the tank. and electrically connect each as a separate tank,
The present invention is characterized by providing an on-load tap changer that prevents the generation of metal powder by eliminating a mechanical configuration for tap selection of a tap winding.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, the tap leads 15 drawn out from each tap of the tap winding 22 connected to the high-voltage main winding 21 are connected to thyristor units 23A...23F consisting of anti-parallel circuits made by connecting a predetermined number of thyristors in series and parallel.
and 24A...24F, etc.

Each tap lead 15 has a thyristor unit 23
Connect point A between A...23F and 24A...24F,
...They are connected at F. Also, the thyristor unit 23
One end of A...23F and 24A...24F is installed in a separate tank in parallel and becomes a tap selector 30,
It is connected to the switching switch 28. This switching switch 28 includes main contacts 25A and 25B and a resistor 27 for cutting off current.
Contacts 26A and 26 that turn on and off A and 27B
Consists of B.

In the on-load tap changer configured as described above, for example, when switching from tap A to tap B, the sequence shown in FIG. As a tank separate from the selector 30, the tap selector 30 is configured with a thyristor without mechanical operation and is electrically opened and closed, thereby providing an on-load tap changer that does not generate metal powder. In addition, since the thyristor does not interrupt the load current, the life of the thyristor can be extended, and since the load switching section is located in a separate tank, inspection is easy, and metal powder generated by mechanical operation can be removed periodically. Inspections can be carried out efficiently and in a short time.

The firing method of the thyristor may be an electric pulse or a light pulse. Further, FIG. 1 shows a case where the high voltage main winding 21 and the high voltage main winding 21 are arranged in the same tank. However, the same effect can be obtained even when the tap winding 22 is in a separate tank as in a transformer with a voltage regulator. Furthermore, although the switching switch 28 is shown as a 4-contact, 2-resistance type, any type of switching switch, such as a 3-contact, 2-resistance type, may be used, and the present invention can be applied regardless of the winding structure of the transformer. Can be done.

〔Effect of the invention〕

As explained below, according to the present invention, a switching switch that involves mechanical operation is housed in a tank separate from the tap winding, high-voltage main winding, and tap selector, and the tap selector is electrically connected. By using a thyristor that shuts off, the generation of metal powder can be prevented by eliminating mechanical movement in the tank with the winding, thereby providing a highly insulated and reliable on-load tap changer. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a composition showing an embodiment of the present invention, and FIG. 2 is a sequence diagram showing the operation of FIG. 1. 21...High voltage main winding, 22...Tap winding, 23A,..., 23F; 24A,...,
24F...Thyristor unit, 25A, 25B.
...Main contact, 26A, 26b...Contact. 27A, 27B...Resistor, 28...Switching switch, 30...Tap selector.

Claims (1)

[Claims] A tap changer on load, characterized in that a tap selector consisting of a plurality of thyristor valves is disposed together with an insulating gas in the same tank as a tap winding, and a switching switch is housed in a tank separate from the tank.