JP2023112227A - On-load tap changer and transformer - Google Patents

Abstract

To provide an on-load tap changer and a transformer capable of suppressing contact damage and overheating and surely suppressing a float voltage.SOLUTION: An on-load tap changer disposed in a transformer having a main winding and a tap winding includes an electrical path having a nonlinear voltage suppression element including a nonlinear resistor and a resistive element connected in series with the nonlinear voltage suppression element between the tap winding and the main winding.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to on-load tap-changers and transformers.

Transformers with on-load tap changers are conventionally used. Also, in the on-load tap changer, a method is known in which the tap winding connection method is changed from transition switching to polarity switching to omit the rough tap winding and reduce the tank diameter.

In the above-described on-load tap changer by polarity switching, the tap winding is temporarily ungrounded (floated) during the operation of the sub-changer for polarity switching. At this time, if the tap winding having the sub-switch is arranged opposite to the high-voltage winding, a float voltage is generated in the tap winding through the capacitance between the high-voltage winding and the sub-switch. There was a problem that discharge occurred at the contact of the

As a method of suppressing the float voltage, there is a method of connecting a resistor called a tie-in resistor between the main winding and the tap winding. However, this method has the problem that the current constantly flows through the tie-in resistor, increasing the loss of the transformer. Furthermore, in gas-insulated transformers that use normal-pressure or pressurized gas as an insulating and cooling medium, the heat capacity of gas is smaller than that of oil, so temperature rise due to loss is also a problem.

Another method of suppressing the float voltage is to provide a shield between the opposing winding and the tap winding. However, in this method, although the float voltage is not generated, the problem is that the insulation distance increases and the winding becomes large.

As another method of suppressing the float voltage while avoiding the above problems, a method of using a lightning arrester (arrestor), which is a nonlinear resistance element using a zinc oxide element, has been proposed. This method will be described with reference to FIG. 5, 1 is the main winding, 2 is the tap winding, 3 is the arrester, 5 is the on-load tap changer sub-switching terminal (upper end), 6 is the on-load tap changer sub-switching terminal (lower end), 7 is a ground side connection terminal of the tap selector, and 8 is a neutral point terminal. As shown in FIG. 5 , an arrester 13 is connected to the neutral point terminal 8 side of the main winding 1 , and this arrester 13 is connected to one of the intermediate terminals of the tap winding 2 . In this way, by using the arrester 13, which is a nonlinear resistance element that causes a current to flow when the voltage value rises above a certain value, the float voltage can be suppressed without generating a loss because current does not flow during operation. can be done.

JP-A-62-095924

In the method of suppressing the float voltage using the arrester described above, no current flows during operation, so no loss occurs. A large current may flow when switching on and damage the contact of the on-load tap changer sub-switching terminal. In addition, since the arrester overheats when a large current flows when it floats, there is also a problem that restrictions remain on repeated operation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The purpose is to provide a vessel.

An on-load tap changer of an embodiment is an on-load tap changer arranged in a transformer having a main winding and a tap winding, wherein between the tap winding and the main winding, An electrical path is provided having a nonlinear voltage suppression element comprising a nonlinear resistor and a resistive element connected in series with the nonlinear voltage suppression element.

According to the embodiments of the present invention, it is possible to provide an on-load tap changer and a transformer that can suppress the occurrence of contact damage and overheating and reliably suppress the float voltage.

1 is a diagram schematically showing a schematic configuration of main parts of a transformer having an on-load tap changer according to the first embodiment; FIG. The figure which shows typically the principal part schematic structure of the transformer with the on-load tap changer which concerns on 2nd Embodiment. The figure which shows typically the principal part schematic structure of the transformer with the on-load tap changer which concerns on 3rd Embodiment. The figure which shows typically the principal part schematic structure of the transformer with the on-load tap changer which concerns on 4th Embodiment. The figure which shows typically the principal part schematic structure of the transformer with the conventional on-load tap changer.

Hereinafter, the details of the on-load tap changer and the transformer according to the embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram schematically showing a schematic configuration of a main part of a transformer having an on-load tap changer according to the first embodiment, and shows a mode of electrical connection in a tap winding 2 in a static induction electric machine. ing. In the first embodiment, the tap winding 2 is connected to the neutral point terminal 8 side of the main winding 1, that is, to the ground side. The on-load tap changer according to the first embodiment is of a polarity switching type, and the on-load tap changer sub-changer terminal (upper end) 5 and the on-load tap changer sub-changer terminal (lower end) 6 are connected to is used to switch the polarity of the tap winding 2 .

In the state shown in FIG. 1, a circuit is not connected to any terminal of the on-load tap changer sub-changer terminal (upper end side) 5 and the on-load tap changer sub-changer terminal (lower end side) 6. It shows the case where the tap winding 2 is in a floating state.

On the neutral point terminal 8 side of the main winding 1 , a nonlinear voltage suppressing element (arrestor) 3 and an electric path are provided in which a resistive element 4 is connected in series with the nonlinear voltage suppressing element 3 . This electrical path (resistive element 4) is connected to one of intermediate terminals (not shown) of the tap winding 2. FIG. The nonlinear voltage suppression element 3 is composed of a nonlinear resistance element using a zinc oxide element or the like, and has a high resistance value when the voltage value is less than a certain value, so that almost no current flows. On the other hand, when the voltage value rises above a certain value, the resistance becomes low and current flows to suppress the voltage rise. The resistance element 4 is composed of a normal resistance element (linear resistance element) having a predetermined resistance value, and as the resistance element 4, for example, one having a resistance value of several tens of kilohms to several hundred kilohms is preferably used. be able to.

The ground connection terminal 7 of the tap selector in the on-load tap changer is connected to any intermediate terminal (not shown) of the tap winding 2 or to the neutral terminal 8 of the main winding 1. However, in the example shown in FIG. 1, it is connected to the neutral terminal 8 of the main winding 1.

In the first embodiment having the above configuration, the voltage generated in the tap winding 2 in the floating state is suppressed by the nonlinear voltage suppressing element 3, and the resistance element 4 suppresses the current caused by the operation of the nonlinear voltage suppressing element 3. , it is possible to prevent overcurrent from occurring in the nonlinear voltage suppressing element 3, the on-load tap changer sub-changer terminal (upper end) 5, and the on-load tap changer sub-changer terminal (lower end) 6. .

Due to the above operation, in the first embodiment, it is possible to prevent damage caused by discharge due to the float voltage at the contacts of the on-load tap changer, and to It is possible to suppress temperature rise due to overcurrent flowing through the switch terminal (upper end) 5 and the on-load tap changer sub-changer terminal (lower end) 6 .

(Second embodiment)
FIG. 2 is a diagram schematically showing the schematic configuration of a main part of a transformer having an on-load tap changer according to the second embodiment, and shows the manner of electrical connection in the tap winding 2 in a static induction electric machine. ing. The same reference numerals are given to the parts corresponding to those of the first embodiment shown in FIG.

In the second embodiment, the connection destination of the resistance element 4 is a 1/2 voltage tap, at which the voltage (potential) of the tap terminals 9 and 10 of the tap winding 2 is approximately 1/2 that of the entire tap winding 2 . A terminal 10 is used.

In the second embodiment having the above configuration, the same effect as in the first embodiment can be obtained, and the connection destination of the non-linear voltage suppression element 3 and the resistance element 4 is set so that the voltage of the tap winding 2 is about 1/2. By setting the 1/2 voltage tap terminal 10 as follows, the maximum potential rise value of the tap winding 2 due to voltage float can be minimized.

(Third embodiment)
FIG. 3 is a diagram schematically showing the schematic configuration of a main part of a transformer having an on-load tap changer according to the third embodiment, and shows the manner of electrical connection in the tap winding 2 of a static induction electric machine. ing. 1 and 2 are denoted by the same reference numerals, and overlapping descriptions are omitted.

In the third embodiment, as in the second embodiment, the potential of the tap terminals 9 and 10 of the tap winding 2 is about 1/2 that of the entire tap winding 2. A 1/2 voltage tap terminal 10 is used. Further, in the third embodiment, a tap winding protection circuit is provided between both ends of the tap winding 2 and a 1/2 voltage tap terminal 10 at which the voltage of the entire tap winding is approximately 1/2. In addition, an arrester 11 (total two) is provided.

In the third embodiment having the above configuration, it is possible to obtain the same effects as those of the first and second embodiments, and in addition to the float of the tap winding 2, the function of protecting the tap winding 2 from an external surge. can be added.

(Fourth embodiment)
FIG. 4 is a diagram schematically showing the schematic configuration of a main part of a transformer having an on-load tap changer according to a fourth embodiment, and shows the manner of electrical connection in the tap winding 2 in a static induction electric machine. ing. 1, the second embodiment shown in FIG. 2, and the third embodiment shown in FIG. 3 are denoted by the same reference numerals, and overlapping descriptions are omitted. .

In the fourth embodiment, of the two tap winding protection arresters 11 provided in the third embodiment, the tap winding protection arrester 11 connected in parallel with the nonlinear voltage suppression element 3 and the resistance element 4 is replaced. It has an omitted configuration.

In the fourth embodiment having the above configuration, the same effects as those of the first, second, and third embodiments can be obtained, and the nonlinear voltage suppressing element 3 and the resistance element 4 for suppressing the float voltage are , one of the tap winding protection arresters 11 can be omitted by imposing the function of protecting the tap winding 2 from external surges. This makes it possible to obtain a more compact tap winding and on-load tap changer than in the case of the third embodiment.

Although several embodiments of the invention have been described above, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1 Main winding 2 Tap winding 3 Non-linear voltage suppression element (arrestor) 4 Resistive element 5 Sub-switching terminal of on-load tap changer (upper end side) 6 … Load tap changer sub-changer terminal (lower end side), 7 … Earth side connection terminal of tap selector, 8 … Neutral point terminal, 9 … Tap terminal, 10 … 1/2 voltage tap terminal , 11... arrester for tap winding protection, 13... arrester.

Claims (5)

An on-load tap changer disposed in a transformer having a main winding and a tap winding, comprising:
An electrical path is provided between the tap winding and the main winding, the electrical path having a nonlinear voltage suppression element made of a nonlinear resistance and a resistive element connected in series with the nonlinear voltage suppression element. On-load tap changer.
The on-load tap changer of claim 1, wherein
characterized in that the non-linear voltage suppression element and the resistance element are connected between a tap terminal at which the potential of the tap winding is 1/2 of the overall potential and the neutral point terminal of the main winding. on-load tap changer.
3. The on-load tap changer of claim 2, wherein
An on-load tap characterized in that a tap winding protection arrester is disposed between both ends of the tap winding and a tap terminal at which the potential of the tap winding is 1/2 of the overall potential. Switcher.
3. The on-load tap changer of claim 2, wherein
a tap winding only between one end of the tap winding that is not connected in parallel with the non-linear voltage suppression element and the resistive element and a tap terminal at which the potential of the tap winding is 1/2 of the overall potential An on-load tap changer comprising a protective arrester.
A transformer having a main winding and a tap winding, characterized in that it comprises an on-load tap changer according to any one of claims 1 to 4.

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