JPS6065508A - Current transformer - Google Patents

Abstract

PURPOSE:To reduce a leakage flux and to minimize the cross-sectional area of an iron core by providing the secondary winding comprising splitted windings, the first leakage flux reduction windings and the second leakage flux reduction windings. CONSTITUTION:The secondary winding 5 is composed of splitted windings 5a- 5c, the first reduction windings 6a-6c and the second reduction splited windings 7a-7c totally. Consequently, the leakage flux phi6b by the first reduction winding 6b and the leakage flux phi7b' and phi7b'' by the second reduction splitted windings 7b' and 7b'' are in the inverse direction to the leakage flux phi5b by the splitted winding 5, and these leakage flux phi5b, phi6b, phi7b' and phi7b'' cancel one another resulting in the reduction of the leakage flux. Accordingly, the first reduction winding 6b and the second reduction splitted windings 7b' and 7b'' reduce the leakage flux phi5b generated by the splitted winding 5b in the whole of the inside of the secondary winding 5. Then the magnetic flux passing through an iron core 2 attains the magnetic flux density which does not cauase a magnetic saturation thereby minimizing the cross-sectional area of the iron core 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feedthrough current transformer having a structure in which the secondary winding is divided, and particularly to a structure for reducing the size and weight of the current transformer.

[Prior art]

Figure 1 ((Z) is a partially sectional side view of a conventional feed-through current transformer, Figure 1(b) is a line taken along A-A' in Figure 1(a))
The cross-sectional view and FIG. 2 show the connection diagram of each divided winding. In each of the above figures, the current transformer has an annular iron core (2) provided around a bus bar (1) which is a primary conductor, and an insulating tape (3) wrapped around the entire surface of the iron core (2). # On the upper layer of the insulation tape (3), the secondary winding (4) is divided into six divided windings (4α) ~ (
4C) (Other three divided windings are omitted in the above figures)
The above-mentioned divided winding (4α) to (4
C) is connected in series and has a predetermined number of turns as a secondary winding.

In this way, the conventional current transformer has a secondary winding (4 cL) ~
(4C) was divided and wound around the iron core (2), so when the visiting secondary current i1 flows through the secondary windings C4tL) to (4C), the spinning secondary, A leakage magnetic flux OL that does not interlink with the bus bar (1) is generated in the magnetic flux caused by the current i1. Therefore, the magnetic flux passing through the iron core (2) increases locally, that is, the magnetic flux density differs between the parts of the iron core (2) around which the divided windings (4α) to (4C) are wound and the other parts. Therefore, in order for the iron core (2) to have a predetermined magnetic flux density that does not cause magnetic saturation, it is necessary to increase the cross-sectional area of one iron core, and the shape of the current transformer itself has to be made large.

The iron core (2) is, for example, a wound core made by winding a long silicon steel strip without cutting it, and since the silicon steel strip is bonded and fixed with insulating tape, it is extremely resistant to external mechanical forces. It is weak and has a thermal power that causes distortion in the shape and structure of the core (2) itself due to external forces such as vibration during assembly or use, and deteriorates magnetic properties.

[Summary of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and it is possible to reduce leakage magnetic flux and minimize the cross-sectional area of the core, thereby preventing deterioration of magnetic properties and achieving size and weight reduction. This provides a current transformer that can

[Example of actual fiTi invention]

An embodiment of the present invention will now be explained in detail based on FIGS. 3(α) and (1)), FIGS. 4 and 5. FIG. 3(b)) is a side view with a part of the current transformer according to an embodiment of the present invention in cross section, FIG. 3(b) is a B-B sectional view of FIG. 3@), FIG. 4 is a wiring diagram of the windings, and FIG. 5 is an enlarged view showing the direction of the magnetic field regarding one divided winding. In each of the above figures, a current transformer according to an embodiment of the present invention is shown.

Six divided windings m (5a
) Reduction windings (6α) to (60) wound in the opposite direction to the subwindings (5α) to (5C) (+υ lower, referred to as the first reduction winding. Also, only (6b) is shown, (6a) (6
0) is not shown. ), and the first reduction winding (6α)
The above divided windings (5α) to (5C) are placed on both sides of ~(6C).
and the winding direction is the same, and the first reduced winding (6α) ~
Second reduction windings (7a) to (7c) (( 7
Only b) is shown, (7α) and (7C) are not shown. 1-J
The second reduced division winding (7c
L') and (7α"), (7b') and (71)),
By providing (7Q') and (7L:+), the above divided windings (5cL) to (5c) and the first reduction winding (6α)
~(6c) and the second reduced division winding constitute a secondary winding (5) as a whole. And the divided winding (5α)
~(50), first reduction winding (6α) ~(6C), second
Since the reduced division windings (7α') to (7c') and (5) are configured, the current i2 flowing through each winding is in the same direction. That is, the divided windings (5α) to (5C), the second reduced divided windings (7α1) to (7c1), and the reduced windings (6cL) to (6c), which are windings in the opposite direction to the windings. Since the number is larger than the number, the first reduction winding (6α) to (6C
), the current i2 in the same direction as the one-divided winding (5α) to (5C) is generated even though a secondary current in the opposite direction is generated due to the action of the magnetic flux on the bus bar (1) due to the winding in the opposite direction. It will flow.

Further, there is copper between the iron core (2) and the secondary winding (5).

A shielding container (8) made of a non-magnetic good conductor such as aluminum is interposed between the iron core (2) and the secondary winding (5) with insulating tape (3) Qcl to insulate almost the surface of the iron core (2). It is provided all around.

Next, in the current transformer configured as described above, the divided winding (5b), the first reduction winding (6b), and the second reduction divided winding (7b) (7b) are formed. When the relationship of leakage magnetic flux is divided based on FIG. 5, the magnetic flux at the boundary between the first reduced winding (6b) and the second reduced divided winding (7b) (7b) is divided as shown in the figure. The leakage flux 5zr5b due to the winding (5b) is in an opposite direction to the leakage flux z6b due to the first reduction winding (6b) and the second decrease 7b, and each leakage magnetic flux 〆5b and leakage flux are reduced. I will do it. Therefore, the leakage caused by the first reduction is 05b'f
As a result, the magnetic flux passing through the iron core (2) is prevented from increasing locally, and the iron core r21 is set to a predetermined magnetic flux density that does not cause magnetic saturation. ) can be kept to a small size.

Further, a divided winding (5) outside the secondary winding (5)
The leakage flux due to b) is prevented from passing through the shield container (8) to the outside of the shield container (8), and the total leakage flux generated by the divided winding (5b) is further reduced. Become. Also, the above shield container (8)
Since the iron core (2) is covered with a fully flexible material such as copper or aluminum, it is possible to improve mechanical strength against external forces such as vibration during assembly or during use. 2) Eliminates distortion in its shape and structure to prevent deterioration of magnetic properties.

The shield container (8) is provided with a slit (9) consisting of a groove-shaped opening over the entire inner circumference in the longitudinal direction of the circumference, and is generated by excitation magnetic flux passing through a magnetic path formed by the iron core (2). The slit (9) prevents the induced current from flowing. This shield container (8) has an iron core (2
) and the divided winding (5) are insulated by the insulating tape (3) and αO wound inside and outside.

Note that the ratio of the number of turns of each winding that constitutes the secondary winding (5) can also be changed to an arbitrary ratio that cancels out the leakage magnetic fluxes. In the above embodiment, the first reduction windings (6α) to (6C) and the second reduction windings (7α) to (
7c) is provided inside the divided windings (5α) to (5c), but it may be provided outside. In addition, the above shield container (8)
The slit (9) may be provided at any location inside or outside, as long as it is provided over the entire circumference of one circumference in the longitudinal direction.

〔Effect of the invention〕

As explained above, the present invention employs a configuration in which the secondary winding is formed by a divided winding, a first reduction winding, and a second reduction winding, so that leakage flux can be reduced. What is possible is that it is possible to prevent the magnetic flux passing through the core from increasing locally, and to minimize the core cross-sectional area corresponding to a predetermined magnetic flux density without causing magnetic saturation in the core. This has the effect that it can be made smaller and lighter.

[Brief explanation of the drawing]

Figure 1 (α) is a front view showing the conventional Aiyodo and vessel; Figure 1 (g)
b) is a sectional view taken along A-p of Fig. 1 (α), Fig. 2 is a wiring diagram of the divided winding, and Fig. 3 (b) is a front view of a current transformer according to an embodiment of the present invention. , Fig. 3(1)> is B- in Fig. 3(a)
B sectional view, FIG. 4 is a wiring diagram of each winding constituting the secondary winding, and FIG. 5 is an enlarged view showing the direction of the magnetic field regarding one divided winding. [1): Bus bar (2) Two iron cores (31, Ql: Insulating tape (41 (5): Secondary winding (
4α) (41)) (40), (51Z) (51) )
(5C): Split winding (6α) (6b) (60)
: First reduction winding (7α) (711) (70) : Second reduction winding (7α') (71)") (7(!'),
(7α"><ri')<ra'"): Second reduced split winding (8): Shield container (9) Nislit agent Masuo Oiwa

Claims (1)

[Claims] (1) - A ring-shaped iron core is provided around the bus bar, which is the secondary conductor,
In a current transformer in which divided windings in which a secondary winding is divided are wound at a predetermined gap around the periphery in the magnetic path direction of the iron core, a winding of the divided winding is arranged near the center of each of the divided windings. A first leakage flux reducing winding wound in the opposite direction, and both of the first leakage flux reducing winding (1) 1 HA part in the same direction as the winding direction of the split winding. A current transformer comprising a secondary winding having a first leakage flux reducing winding and a second leakage flux reducing winding formed of the same number of turns as the first leakage flux reducing winding. 2. The current transformer according to claim 1, further comprising a shielding container made of a non-magnetic electrically conductive material such as RAM.