JPH043656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-core reactor.

For example, an AC filter used in a power system is composed of a reactor, a capacitor, and a resistor. In these configurations, not only the inductance but also the resistance of the reactor itself may be used as the resistance for the filter described above, and therefore, the reactor may be designated with an effective resistance. Therefore, in order to obtain this resistance, a conventional air-core reactor of an electromagnetic shielding air-core type in which an air-core coil is surrounded by a shield is shown in FIG. That is, 1 is an air-core coil, and 2 is a conductive shield made of copper, aluminum, etc., which has a pipe shape, for example, and is arranged around the coil 1. This is usually stored in a steel tank. Furthermore, in this air-core reactor, in order to adjust the inductance value, a tap coil 3 is provided in the center of the coil 1, and by changing the tap connection, the tap coil 3 can be inserted into or removed from the coil 1, and the total number of turns of the coil 1 can be changed. , that is, the inductance is changed. To change this tap connection, a voltageless tap changer is used, as in a transformer.

However, in this air-core reactor, when the tap coil 3 is wound around the center of the main coil 1, it requires time and skill to pull out the tap lead in the tap coil 3, which causes a significant decrease in the winding work efficiency. Also, depending on the connection state of the taps, all the tap coils 3 may be disconnected from the energized circuit, but in this case, the ampere turns for all the tap coils will be disconnected at the center of the coil 1, and therefore the magnetic flux will be at the center of the coil as shown in the figure. bending occurs. The solid line 4 in the figure shows the flow of magnetic flux when the tap coil 3 is connected, and the dotted line 4' shows the flow when the tap coil 3 is disconnected. As a result of the disturbance of the magnetic flux passing through the coil 1, stray loss within the coil 1 and circulating current loss between the parallel wires of the coil 1 increase, degrading the characteristics and quality of the reactor.

Furthermore, since a tap changer is equivalent to a coil in terms of insulation, it requires a fairly large size and insulation space in the case of high voltage, which has been an obstacle to making the device more compact.

Therefore, an object of the present invention is to provide an air-core reactor that does not complicate the winding work, reduces the insulation of the tap changer, and allows the inductance to be adjusted without deteriorating the quality. .

An embodiment of this invention is shown in FIGS. 2 and 3. In other words, this air core reactor has coil 1
A non-magnetic conductive shield 2 is arranged around the outer periphery of the shield 2, and a plurality of tap coils 5 are arranged concentrically with the shield 2 near the inside of the shield 2. One end of each tap coil 5 is grounded, and a short circuit switch 6 is connected to each end of the tap coil 5. Connected.

With this configuration, when the short circuit switch 6 is closed, the tap coil 5 is short-circuited and grounded, and when it is open, it becomes an open circuit with one end grounded. and,
The inductance is adjusted by shorting the tap coil 5. That is, when the tap coil 5 is short-circuited, an induced current flows through the tap coil 5 due to the electromagnetic coupling effect with the coil 1, and this current pushes the magnetic flux of the coil 1 to the inside of the short-circuited tap coil 5, so that the shield appears to be localized. This is the same as approaching the coil 1 to the position of the short-circuited tap coil 5, and the inductance decreases. On the other hand, when the switch 6 is open, no current flows, so there is no effect on the inductance.

In the case of the embodiment, there are three tap coils 5, which are arranged at different intervals in the axial direction. This is to make the change in inductance caused by a short circuit of the tap coil 5 different from each other, and by doing this, eight types of inductance values can be obtained. That is, all tap coils 5a~
One type when 5c is open, tap coils 5a to 5
There are three types when any one of c is closed (short circuit),
There are three types when any two of the tap coils 5a to 5c are closed, and one type when all tap coils 5a to 5c are closed.

As a result, this air-core reactor has the following effects. That is, (1) Since the tap coil is not wound around the center of the coil 1, the winding work becomes easier and efficiency increases.

(2) Due to the connected state of the tap coil 5, the magnetic flux within the coil 1 is not disturbed, leading to improvements in the characteristics and quality of the reactor.

(3) Since the tap coil 5 is placed near the grounded shield 2 and one end is grounded,
It can be made separately from the insulation of the coil 1 and made of a material with low insulation strength.

(4) The conventional tap changer required a switch suitable for the insulation class of the coil 1, but due to the reason (3) above, the switch 6 with low insulation strength can be used and the switch can be downsized.

(5) Since the tap coil 5 to be shorted can be freely selected, three tap coils 5 can be short-circuited.
Eight combinations can be easily obtained from a to 5c.
In this respect, in the conventional type, seven tap coils were required to obtain eight types of inductance.

(6) Since the tap coil 5 is not provided in the main coil 1, the main coil 1 is not limited by the number of turns, and more precise inductance can be obtained.

As described above, the air-core coil of the present invention has a grounded tap coil inside the shield, and this tap coil is short-circuited by a short-circuit switch, so that the inductance can be adjusted, and the work is easy and efficient. This has the effect of reducing insulation, making it more compact, and improving the characteristics and quality of the reactor.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view of a conventional example, FIG. 2 is a half-sectional view of an embodiment of the present invention, and FIG. 3 is a partial plan view thereof. 1...air core coil, 2...shield, 5...tap coil, 6...short circuit switch.

Claims (1)

[Claims] 1. An air-core coil, a non-magnetic conductive shield placed around this coil, an inductance adjustment tap coil placed in a coaxial cylindrical shape near the inside of this shield and grounded at one end, and a tap coil placed at both ends of this tap coil. Air core reactor with connected short-circuit switch.