JPS596111Y2 - transformer protection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a transformer protection device, and more particularly to a transformer protection device that protects a transformer in which a gapless lightning arrester is inserted inside the transformer from surge voltages and currents.

Conventionally, in this type of transformer protection device, a lightning arrester for protecting the transformer has been mounted on a separate mount or near a bushing on the transformer body.

In other words, FIG. 1A shows an example of a conventional transformer protection device. In FIG. 1A, 1 is the transformer main body, and 2 is the high voltage side bushing 3 installed on the transformer main body 1, which is the low voltage side bushing 3. A bushing 4 is a lightning arrester attached to a mowing stand 5, and the high voltage side bushing 2 and the lightning arrester 4 are connected by a lead wire 6.

In the transformer protection device shown in FIG. 1A, the lightning arrester 4 is attached to a separate pedestal 5, which requires an area corresponding to that amount, which increases the construction cost.

FIG. 1B shows another example of the conventional transformer protection device, in which a lightning arrester 4 is attached to the transformer body 1 via a support frame 7, and the transformer shown in FIG. In addition to this protective device, it also had the following drawbacks:

That is, when a lightning arrester is mounted on the transformer main body, the high voltage exposed portion increases due to the lead wire connection, which is not good for aesthetics or safety.

Further, if the lightning arrester is built into the transformer, the above problems can be solved, but conventional lightning arresters have various problems for the following reasons.

(b) If a large impulse current flows through a lightning arrester due to multiple lightning or close lightning, it may lose its function and burn out.

In such cases, it is generally allowed under the standards as it is unavoidable that the lightning arrester burns out, but if the transformer also burns out, the power supply will be interrupted for a long period of time and there will be a large economic loss. becomes.

(b) Conventional lightning arresters have a series gap, so
It cannot be directly immersed in transformer oil.

In addition, in order to incorporate it, it is necessary to take measures such as attaching a special condenser cone and inserting it into an oil-tight container.
It is disadvantageous in all respects such as weight and economy.

The present invention has been made in view of the above-mentioned points, and its purpose is to directly immerse a gapless surge arrester in transformer oil, connect two phases as one unit between the oil-immersed terminals of a lead-in bushing, and It is an object of the present invention to provide a transformer protection device that has high performance and can be made compact by grounding the central part of a gapless lightning arrester.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transformer protection device according to an embodiment of the present invention will be described below with reference to FIGS. 2 to 5.

FIG. 2 schematically shows a transformer protection device according to an embodiment of the present invention, in which a coil core 8 is housed in a transformer body 1 and is filled with insulating oil.

A high voltage side winding (not shown) wound around the coil core 8 is connected to coil lead wires 9a, 9b and high voltage side bushing 2.
It is connected to the power supply side via a and 2b.

A first lightning arrester 10a and a second lightning arrester 10b, which have non-linearity and high dielectric constant resistive elements such as zinc oxide as a characteristic element and have no gap, are inserted between the bases of the high-voltage side bushings 2a and 2b. It is set up.

That is, each lightning arrester 10a, 10b is electrically connected to the high-voltage side winding, and each gapless lightning arrester 10a, 10b is electrically connected to the internal escape part 1a of the transformer body 1, thereby grounding. It is shaped like this.

More specifically, as shown in FIG. 3A, a plurality of non-contact elements whose main component is zinc oxide are interposed between the disc-shaped electrode plate 12a and the intermediate support/grounding terminal plate 13 via disc springs 14. Linear resistance elements 15a are stacked.

Also, an intermediate support/grounding terminal plate 13 and a disk-shaped electrode plate 12
A non-linear resistance element 15b also made of zinc oxide is laminated between the electrode plates 12a and 12b, and an insulating bolt 16 and a nut 17 are tightened between the electrode plates 12a and 12b.

A plurality of insulating bolts 16 are provided at equal intervals so as to be located on the outer periphery of the stacked non-linear resistance elements.

The first gapless lightning arrester 10a is shaped like an element by the non-linear resistance element 15a interposed between the electrode plate 12a and the intermediate support/grounding terminal plate 13, and the non-linear resistance element 15a is interposed between the grounding terminal plate 13 and the electrode plate 12b. The interposed non-linear resistance element 15b is the second
A gapless lightning arrester 10b is formed.

The intermediate support/grounding terminal plate 13 is connected to the upper inner wall 1 of the transformer body 1.
It is attached to a support fitting 18 attached to a and is in a grounded state.

Electrode plate 12a in first gapless lightning arrester 10a
The connecting terminal bar 11a is connected to the electrode plate 12b of the second gapless lightning arrester 10b.
1b are connected.

Therefore, as shown in FIG.
a and the second gapless lightning arrester 10b are coil lead wires 9
It is electrically connected between a and 9b, and is grounded via the intermediate support/grounding terminal plate 13 and the transformer body 1.

According to the transformer protection device having the above structure, the gapless lightning arresters 10a and 10b using the nonlinear resistance elements 15a and 15b whose main components are zinc oxide do not use a series gap. Therefore, it can be directly immersed in insulating oil.

The two gapless surge arresters 10a and 10b are supported horizontally by a support/ground terminal plate 13.

Therefore, the transformer protection device shown in FIGS. 2 and 3 can be represented by the equivalent circuit shown in FIG. 5A.

In FIG. 5A, 21 is a transformer, 21 a is a high voltage side winding, and 21 b is a low voltage side winding.

A first gapless lightning arrester 10a and a second gapless lightning arrester 10b connected in series are connected in parallel to the high voltage side winding 21a of the transformer 21, and the gapless lightning arrester 10 is connected in parallel to the high voltage side winding 21a of the transformer 21.
The connection point between a and 10b is connected to ground 22.

Therefore, the surge voltage and current coming from the high voltage side bushings 2a and 2b are transferred to the first gapless lightning arrester 10a.
, the ground 22 through the second gapless arrester 10b.
The transformer 21 is protected.

FIG. 4 shows another embodiment of the present invention. In this embodiment, an insulating tube 19 is connected to a support fitting 18 attached to the inner wall 1a of the transformer body 1 via a hollow disc 20a.
is installed.

A non-linear resistance element 15C whose main component is zinc oxide is inserted into this insulating cylinder 19, and this non-linear resistance element 15C is attached to the insulating cylinder 19 via a disc spring 14 and a hollow disc 20b. The third electrode plate 12C is fixed by pressure contact with the
A gapless lightning arrester 10C is used.

An intermediate support/grounding terminal plate 13 of the first gapless lightning arrester 10a and the second gapless lightning arrester 10b is attached to the electrode plate 12C of the third gapless lightning arrester 10C.

The transformer protection device shown in FIG. 4 can be represented by the equivalent circuit shown in FIG. 5B.

That is, the difference from FIG.
0C is connected.

Therefore, the surge voltage and current coming from the high voltage side bushings 2a and 2b are transferred to the first gapless lightning arrester 10a.
, the second gapless lightning arrester 10b and the third gapless lightning arrester 10c to the ground 22, so that the transformer 21 is protected.

In each of the above embodiments, when each gapless lightning arrester is connected to the oil-immersed end of each phase bushing, it is effective to provide a shield ring at these connection parts.

As explained above, in the present invention, by employing a gapless surge arrester, all the problems encountered when using a conventional surge arrester are solved.

In other words, the gapless lightning arrester does not use a series gap and does not allow a follow-on current to flow, so even if a large current flows due to multiple lightning or close lightning, it will not burn out due to the inability to disconnect the series gap unlike the conventional type.

Furthermore, since no series gap is used, the firing voltage does not change due to the insulating medium.

Therefore, according to the present invention, the following various effects can be obtained.

(1) Complete lightning protection with almost no change in transformer dimensions;
Surge resistance can be obtained.

(2) Mount for lightning arrester, space, on-site installation,
Although wiring work is not required and the cost of the transformer itself increases slightly, there is a large economic effect overall.

(3) Since the protection distance is approximately zero even against steep lightning surges, complete protection is possible and is effective in improving the reliability of power supply.

(4) Excellent in terms of environmental harmony.

[Brief explanation of the drawing]

1A and 1B are schematic diagrams of a conventional transformer protection device, and FIG. 2 is a longitudinal sectional front view of the transformer protection device of the present invention.
FIG. 3 is a front sectional view of the main parts thereof, and FIG. 4 is a front sectional view showing the main parts of a transformer protection device according to another embodiment of the present invention.
Fig. 5A is an equivalent circuit diagram of the device shown in Fig. 3, and Fig. 5B is an equivalent circuit diagram of the device shown in Fig. 3.
FIG. 3 is an equivalent circuit diagram of the device shown in the figure. 1...Transformer body, 2a, 2b...High voltage side bushing, 8...Transformer coil core, 9
a, 9 b... Coil leader wire, 10 a.
...First gapless lightning arrester, 10b...
...Second gapless lightning arrester, 10C...
Third gapless lightning arrester, 13...Support and ground terminal plate, 22...Ground.

Claims (1)

[Scope of utility model registration request] Nonlinearity is a problem in a transformer in which a coil core is housed in a main body sealed with insulating oil, and a high-voltage side winding wound around the coil core is connected to the power supply side via a high-voltage side bushing. Use a non-linear resistor with a high dielectric constant as an internal element 2
A gapless surge arrester is formed by electrically and mechanically connecting several surge arrester units in series, and the gapless surge arrester is disposed between the upper part of the coil core and the upper inner wall of the main body, and the gapless surge arrester is A protection device for a transformer, characterized in that the center portion is supported by a grounding terminal member.