JPH10144549A - Double ratio current transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible coping with overcurrent by using a thin secondary coil, by winding two secondary coil wires around a ring type iron core, with the number of turns corresponding to a specified maximum current ratio of a primary current and a secondary current. SOLUTION: Two secondary coil wires 1a, 1b which are thinner than the conventional coil wire are wound together around a ring type iron core with the number of turns corresponding to 1/2 the maximum current ratio of a primary current and a secondary current. Tap terminals 4a, 4b are arranged on both ends of one secondary coil wire 1a, and tap terminals 4b', 4c are arranged on both ends of the other secondary coil wire 1b. The tap terminals 4b, 4b' of the two secondary coil wires 1a, 1b are connected and make a series connecting state. Otherwise, the tap terminals 4a, 4b' of the two secondary coil wires 1a, 1b are connected and the tap terminals 4b, 4c are connected, so that a parallel connecting state is obtained. When this current transformer is used at the maximum current ratio, a series connecting state is selected. When it is used at the minimum current ratio, a parallel connecting state is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double ratio current transformer for measuring and detecting a current flowing in a power system.

[0002]

2. Description of the Related Art A conventional double ratio current transformer is shown in FIG.
(B), as shown in FIG. 4 and FIG.
One secondary coil wire 1 having a sectional area capable of withstanding the secondary side overcurrent is connected to a maximum current ratio between the primary current and the secondary current (for example,
The secondary coil 3 is formed by winding around the ring-shaped iron core 2 by 1000: 5), and tap terminals 4 are provided at both ends of the secondary coil wire 1.
a, 4c were provided, and the intermediate tap terminal 4b was drawn out from the number of turns where the current ratio of the secondary coil wire 1 was 1/2 of the aforementioned maximum current ratio.

[0003] Such a double ratio current transformer is composed of a primary current and a secondary current.
When the current ratio with the secondary current is the maximum current ratio (for example, 1000: 5), the secondary current is extracted from the tap terminals 4a and 4c, and the current ratio between the primary current and the secondary current is the minimum current ratio ( For example, tap terminal 4 when using at 500: 5)
The secondary current is extracted from a and 4b.

[0004]

When a double-ratio current transformer having such a structure is used, for example, as a current transformer in a gas-insulated switchgear (GIS), the GIS pipeline itself is used. , There are severe dimensional restrictions.

For this reason, if a thick wire having a cross-sectional area capable of withstanding the primary side overcurrent flowing at the time of failure is used as the secondary coil wire 1, the winding thickness of the secondary coil wire 1 increases and the secondary coil wire 2 has a predetermined size. There was a problem that the next coil 3 could not be manufactured.

The reason why a thick wire must be used as the secondary coil wire 1 in the conventional double ratio current transformer is as follows. Usually, the cross-sectional area of the secondary coil wire 1 of the double ratio current transformer is
Since it is determined by the current ratio between the primary current and the secondary current and the overcurrent value of the system (that is, the overcurrent value flowing through the primary conductor of the double ratio current transformer), the structure shown in FIG. I have to use thick wires. That is, the primary current of the double ratio current transformer and 2
Assuming that the maximum current ratio with respect to the secondary current is, for example, 1000: 5 and the minimum current ratio is, for example, 500: 5, when an overcurrent of 20 kA flows in the primary conductor of this double ratio current transformer, 1000: 5 In the case of the ratio of 5, overcurrent of 20 times the rated current flows in the secondary coil wire, whereas in the case of the ratio of 500: 5, the overcurrent of 40 times of the rated current flows in the secondary coil wire. Therefore, it is necessary to make the required sectional area of the secondary coil wire having the smaller current ratio larger than the required sectional area of the secondary coil wire having the larger current ratio. Therefore, in the conventional double ratio current transformer having the configuration shown in FIG. 4, a thick wire must be used as the secondary coil wire 1 between the tap terminals 4a and 4c for use in a state where the current ratio is small. Did not.

An object of the present invention is to provide a double ratio current transformer which can cope with overcurrent even with a thin secondary coil wire.

Another object of the present invention is to provide a double ratio current transformer which can satisfy the dimensional restrictions required for the secondary coil.

[0009]

SUMMARY OF THE INVENTION A double ratio current transformer according to the present invention comprises two secondary coils having a current ratio of 1/2 of the maximum current ratio between a primary current and a secondary current. The wire is wound around the ring-shaped core.

[0010] The double ratio current transformer having such a configuration is used in a case where the above-mentioned two secondary coil wires are connected in series,
It may be used in parallel connection. In this case, when using at the maximum current ratio, the two secondary coil wires are connected in series, and when using at the minimum current ratio, the two secondary coil wires are connected in parallel.

For this reason, when the secondary coil wire is used at the minimum current ratio at which a large overcurrent flows, the secondary coil wires are in a parallel connection state, so that the required sectional area is equal to the sum of the sectional areas of the two secondary coil wires. It will be good if you have it.

In the double-ratio current transformer having such a structure, a thinner wire can be used as the two secondary coil wires than in the past, and moreover, a half of the maximum current ratio between the primary current and the secondary current can be used. Since it is sufficient to wind two secondary coil wires by the number of turns of the current ratio, the dimensional restriction required for the secondary coil can be satisfied.

[0013]

FIG. 1 shows an embodiment of a double ratio current transformer according to the present invention.

In the double-ratio current transformer of this embodiment, the current ratio of the maximum current ratio of the primary current to the secondary current is に around the ring-shaped core 2 as shown in FIG. With the number of turns, two secondary coil wires 1a and 1b which are thinner than before are wound together,
Tap terminals 4a, 4 are provided at both ends of one secondary coil wire 1a.
b, and tap terminals 4b 'and 4c are provided at both ends of the other secondary coil wire 1b.

The double ratio current transformer having such a configuration is shown in FIG.
As shown in (A), the case where the tap terminals 4b and 4b 'of the two secondary coil wires 1a and 1b are connected to form a serial connection to obtain an output from between the tap terminals 4a and 4c, As shown in FIG. 2 (B), two secondary coil wires 1
a and 1b are connected between the tap terminals 4a and 4b ', and the tap terminals 4b and 4c are connected to form a parallel connection state.
An output may be obtained between the mutually connected tap terminals 4a and 4b 'and the mutually connected tap terminals 4b and 4c.

In such a double ratio current transformer, two secondary coil wires 1a and 1b are connected in series when used at the maximum current ratio, and two secondary coil wires are used when used at the minimum current ratio. The coil wires 1a and 1b are connected in parallel.

For this reason, when the secondary coil wires 1a and 1b are used at the minimum current ratio at which a large overcurrent flows, the secondary coil wires 1a and 1b are connected in parallel. It is sufficient if the sum of the cross-sectional areas of

In the double ratio current transformer having such a structure, a thinner wire can be used as the two secondary coil wires 1a and 1b than the conventional one, and the maximum current ratio of the primary current to the secondary current is 1%. /
It is sufficient to wind the two secondary coil wires 1a and 1b by the number of turns of the current ratio of 2, respectively, so that the dimensional restriction required for the secondary coil can be satisfied.

[0019]

The double ratio current transformer according to the present invention has two turns with a current ratio of 1/2 of the maximum current ratio between the primary current and the secondary current.
Since two secondary coil wires are wound around a ring-shaped iron core, these two secondary coil wires are connected in series when used at the maximum current ratio, and when used at the minimum current ratio. Can be connected in parallel, and when used at the minimum current ratio at which a large overcurrent flows, the secondary coil wires are in a parallel connection state, and the required cross-sectional area is two secondary coil wires. It is only necessary that the sum of the cross-sectional areas has the same value. Therefore, in the double ratio current transformer having such a structure, a thinner wire can be used as the two secondary coil wires than the conventional one, and the current ratio of the maximum current ratio of the primary current to the secondary current is １ ／. Since it is sufficient to wind two secondary coil wires by the number of turns, it is possible to satisfy the dimensional restriction required for the secondary coil.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a secondary coil of an example of an embodiment in a double ratio current transformer according to the present invention.

FIGS. 2A and 2B are diagrams showing two types of connection structures of the secondary coil shown in FIG.

FIGS. 3A and 3B are a plan view and a side view of a conventional double ratio current transformer.

FIG. 4 is an enlarged sectional view taken along line XX of FIG. 3;

FIG. 5 is a diagram showing a structure of a secondary coil of a conventional double ratio current transformer.

[Explanation of symbols]

 1, 1a, 1b Secondary coil wire 2 Ring-shaped iron core 3 Secondary coil 4a, 4b, 4b'4c Tap terminal

Claims (3)

[Claims] 1. A maximum current ratio of 1 between a primary current and a secondary current.
A double ratio current transformer characterized in that two secondary coil wires are wound around a ring-shaped iron core with a number of turns of a current ratio of / 2. 2. The maximum current ratio of the primary current to the secondary current, ie, 1
A double ratio transformer characterized in that two secondary coil wires are wound around a ring-shaped iron core with a number of turns having a current ratio of / 2, and these two secondary coil wires are connected in series. Sink. 3. Two secondary coil wires are wound around a ring-shaped iron core with a number of turns having a current ratio of 1/2 of a maximum current ratio between a primary current and a secondary current. Wherein the secondary coil wires are connected in parallel.