JPS59121814A - Bushing type current transformer - Google Patents

Abstract

PURPOSE:To facilitate polarity comfirming test by providing a wiring for polarity confirming test penetrating through an iron core along its inside and by pulling out at least one end of said wiring with insulating it from a tank. CONSTITUTION:Both ends of a polarity test wiring 8 arranged so as to penetrate through inside of one or plural BCT cores 5a are connected to a terminal 9 built in a terminal box 6 attached to a transformer tank 1. The terminal 9 has an insulated terminal structure and is insulated from the transformer tank 1. Such structure enables to perform the polarity confirming test of the BCT5 easily from the outside without any operation of a main circuit in case of that there are plural BCT iron cores provided.

Description

[Detailed Description of the Invention] [Technology of the Invention (F+ Field)] The present invention relates to a bushing type current transformer that is attached to a bushing outlet of an oil-immersed transformer, and particularly relates to an on-site polarity test after the installation work is completed. This invention relates to a bushing type current transformer with an improved structure to enable easy operation.

[Technical field of invention]

Conventionally, transformers have been provided with air pull-out pushers corresponding to each terminal. In an air-drawing type transformer, a polarity confirmation test of a bushing type current transformer (hereinafter referred to as BOT) built in oil in a tank can be performed by applying an air terminal signal. However, in recent years, underground substations and substations using gas-linked switchgear (G-IS) have become commonplace, and in these cases, transformers are connected by power cables without having to take the main circuit out into the air. A connecting structure is adopted. In such a cable pull-out type current transformer, the main circuit terminals are not exposed to the air. Therefore, when testing the polarity of nine BOTs built in oil, it is often necessary to connect the test lead to the main circuit conductor in the oil, and there is a problem in that it is necessary to disassemble the tank and dispose of the oil on site. there were. In addition, the plugging system for atmospheric extraction of ultra-super high voltage class transformers is 13 meters above the ground, making testing using the main circuit increasingly difficult.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bushing type current transformer that eliminates the above-mentioned drawbacks and incorporates a polarity test winding so that a polarity confirmation test can be easily performed.

[Summary of the invention]

In order to achieve the above object, the present invention provides a bushing type current transformer housed in oil in a tank of oil-filled electrical equipment, and provides a polarity test winding that passes through the iron core. It is characterized in that at least one winding end of the wire is insulated from the tank and drawn out.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a cable pull-out type transformer. 1 is a transformer tank, 2 is a transformer body, 3 is an oil wall penetrator 7/g, and 4 is a power cable. 5 is a BOT attached to the oil wall penetrating push knob 30, 6
shows the terminal box for the drawer lead of BOT5.

Figure 2 is a diagram showing details of the area near the BOT in Figure 1.
indicates a BOT mounting seat, and 5a indicates a BOT core mounted on the BOT mounting seat 7. 8 indicates a polarity test winding installed so as to penetrate through one or more BCT cores 5a,
Both ends of this polarity test winding 8 are connected to terminals 9 built into a terminal box 6 attached to the transformer tank 1.

The terminal 9 has an insulated terminal structure and is insulated from the transformer tank 1.

By attaching the polarity test winding 8 to such a configuration, even if there are multiple BOT cores as shown in the equivalent circuit of Fig. 3, the polarity confirmation test of the BOT 5 can be performed without any modification to the main circuit. This can be easily done externally without adding anything.

That is, a DC power source P having a switch SW is connected to both terminals of the winding T of the transformer connected to the BOT 5 to be measured. Also, a meter M that swings between ten and two poles is connected to the secondary terminal of BOT5. The polarity can be determined by which side the needle of the meter M swings at the moment the switch SW of the power source P is turned on.

Therefore, it is necessary to connect electric wires to the main circuit.

Next, another embodiment of the present invention is shown in FIG. Components that are the same as those in FIG. 2 are designated by the same reference numerals and their explanation will be omitted.

One end of the polarity test winding 8 is connected to the terminal 9 built in the terminal box 6 as in FIG. 2, but the other end is connected to the BOT mounting seat 7.
Connect to the grounding terminal 1o of the
is installed. In this case, there is an advantage that the terminal structure is simplified and connection errors of the polar winding itself can be prevented.

〔Effect of the invention〕

As mentioned above, according to the unexploded BA, in a bushing type current transformer housed in oil in the tank of oil-filled electrical equipment, a polarity test winding that penetrates the core is provided, and at least one of the polarity test windings is Since one end of the winding is insulated from the tank and pulled out to the outside, a polarity confirmation test can be easily performed.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional bushing type current transformer, Fig. 2 is a sectional view showing an embodiment of the present invention, Fig. 3 is an equivalent circuit for polarity testing, and Fig. 4 is another embodiment of the present invention. FIG. 3 is an example cross-sectional view. 1...Transformer tank 2...Transformer body 3...Oil submerged wall through-wall bushing 4...Power cable 5...BOT 5a...Bushing current transformer core 6...Terminal box 7... ... Bushing current transformer mounting seat 8 ... Polarity test winding 9 + 92, 9b ... Terminal 10 ... Ground terminal agent Patent attorney Noriyuki Chika (1 person) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a bushing type current transformer housed in oil in a tank of oil-filled electrical equipment, a polarity test winding is provided that passes through the core, and at least one winding end of this polarity test winding is insulated from the tank. A bushing type current transformer that is characterized by being drawn out to the outside.