JPH0727828B2 - Oil-filled transformer with power factor correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to an oil-filled transformer incorporating a power factor correction device.

BACKGROUND OF THE INVENTION When an inductive load such as a motor is applied, the power factor of the load may deteriorate and the effective power supply capacity may decrease. Therefore, the transformer capacity needs to be larger than the load capacity, which is uneconomical for transformer customers. As a power factor improvement measure, it is common to insert a phase-advancing capacitor in parallel with the load to increase the capacity, but if the transformer and the phase-advancing capacitor are separated, the installation area will be large, and the conventional off-the-shelf transformer will be used. There is a problem that the direction of the terminals is improper because the device is used and the wiring work becomes complicated. Furthermore, there were problems in electrical safety due to the wiring lines and insulation reliability due to dust adhesion and the like. As a related one, there is a utility model No. 57-31834, which is one in which a delta-connected or star-connected phase-advancing capacitor is housed inside a transformer container and directly connected to the secondary side of the transformer. Is. There is no description in this prior art about determining the power factor of the load to obtain an appropriate phase advancing capacitor capacity.

[Object of the Invention]

An object of the present invention is to appropriately control the capacity of the phase-advancing capacitor according to the power factor of the load and to improve the power factor excellently.
An object of the present invention is to provide an oil-filled transformer with a power factor correction device, which has excellent operation reliability of the power factor correction device.

[Outline of Invention]

The present invention relates to a transformer main body including a primary winding that is star-connected, a secondary winding that is delta-connected, and an iron core, and a delta connection that is connected in parallel with the secondary winding of the transformer main body. In an oil-filled transformer with a power factor correction device having a phase-advancing capacitor, a transformer body, and a tank that stores the phase-advancing capacitor in a state of being immersed in insulating oil, a first capacitor, a first reactor, and a first thyristor. A first delta connection circuit in which the first power factor correction element configured in a series circuit of delta connection is connected in a delta connection, and a second capacitor formed of a series circuit of a second capacitor, a second reactor, and a second thyristor. A second delta connection circuit in which power factor correction elements are connected in delta connection, and a third delta connection circuit in which a third power factor correction element configured by a series circuit of a third capacitor, a third reactor, and a third thyristor is connected in delta connection. Dell Supplying ON / OFF signals to the gates of the first thyristor, second thyristor and third thyristor by determining the power factor of the load by detecting the voltage and current on the secondary side of the transformer and the transformer main body. Equipped with a reactive power relay to
The delta connection circuit, the second delta connection circuit, and the third delta connection circuit are respectively connected in parallel with the secondary winding of the transformer main body, and are connected to the lower side of the transformer main body together with the phase advancing capacitor in the tank. The reactive power relay is provided outside the tank.

Example of Invention

FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, in which 1 is a three-phase transformer main body including a three-leg iron core 1a and three coils 1b to 1d wound around each leg, and 2 is the above-mentioned transformer. A power factor correction device arranged at the bottom of the tank below the base 1e of the main body 1 of the reactor, a phase-advancing capacitor 3 as a power factor correction element, a series reactor (composed of an iron core and a coil) 4, and a thyristor as a switching element. 5 and a frame 2a supporting them,
It is immersed in the insulating oil 8 in the tank 9 together with the transformer body 1. The transformer main body 1 has a primary side configured by a star connection and a secondary side delta connection, and an output on the secondary side is connected via a bushing 10 to an external load. 6 turns on the thyristor 5
・ A reactive power relay that gives an OFF signal.
A current signal and a voltage signal are respectively received from the current transformer 7 wound around one of the secondary output lines and the signal line connected to the other two secondary output lines. This relay 6 is arranged outside the tank 9 and constitutes a power factor correction device together with the above-mentioned elements 3, 4 and 5.

FIG. 2 is a circuit configuration diagram of the embodiment, and the same parts as those in FIG. 1 are designated by the same reference numerals. The power factor correction device 2 is composed of four delta connection circuits connected in parallel to the secondary side output line so as to be surrounded by a broken line. The load generally has an inductive reactance, which needs to be compensated. The delta connection circuit configured by the phase advancing capacitor 3a is provided as a basic circuit for this compensation, and is fixedly connected without an opening / closing element such as a thyristor. A reactor having a fixed value may be connected in series to the capacitor 3a.

A first delta connection circuit, a second delta connection circuit and a third
The thyristor 5 is connected in series to the circuit elements on each side, for example, 31 in the other three delta connection circuits as the delta connection circuit. The thyristor 5 is
The ON signal from the relay 6 is closed by being supplied to the base terminal, and the delta connection circuit having the element 31 as the first power factor correction element is connected in parallel to the basic delta connection circuit. Compensating circuit with appropriate phase advancing capacitor capacity. Thyristors are also connected in series for the second delta connection circuit and the third delta connection circuit, each of which is composed of the element 32 as the second power factor improving element and the element 33 as the third power factor improving element. , Compensation circuit is connected in parallel to the base delta connection circuit according to the power factor of the load and has a capacitor and a reactor value suitable for the load.

The relay 6 judges the state of the power factor of the load based on the current signal and the voltage signal from the secondary side output line and the phase difference between the current and the voltage, and the delta connection circuit composed of the elements 31, 32, 33. Apply a pulsed ON / OFF signal to the gate terminal of the thyristor. Therefore, three types of ON / OFF signals are required for each side in one delta connection circuit. In the example of FIG. 2, there are nine types of S1 to S9.
Is required.

Capacitor 3, reactor 4 and thyristor 5 shown in FIG. 1 include the corresponding elements shown in FIG.

In the above-described embodiment, as is clear from the figure, since the electric circuit portion in the tank 9 is almost entirely immersed in the insulating oil 8, the electric insulation and heat dissipation between the circuits are excellent, and the parts are arranged close to each other. And can be made compact. Further, since the wiring between the electric circuits is carried out in the tank, the work of connecting the lead wires when assembled in the cubicle becomes easy. Further, although the transformer main body serves as a heat source, since it is arranged above the tank, it is possible to reduce the thermal influence on the power factor correction device 2, and the operation reliability of the device 2 is improved.

FIG. 3 shows another embodiment. In this example, frame 2a
The phase-advancing capacitor 3 is vertically arranged therein, and the thyristor 5 is arranged at the bottom of the frame 2a.

According to this embodiment, the convection of the insulating oil between the capacitors 3 is improved, and the heat-sensitive thyristor 5 can be provided at the bottom of the tank where the temperature is the lowest, so that the operation of the power factor correction device 2 is stable. The property can be further improved.

The location and the orientation of the series reactor 4 shall be selected so as not to be magnetically affected by the transformer body.

According to the above examples, since the main part of the power factor correction device is installed together with the transformer body in the tank in a state of being immersed in insulating oil, it is possible to configure the transformer with excellent insulation and to make the transformer compact. Wiring work can be facilitated when incorporating into a cubicle.

〔The invention's effect〕

According to the present invention, an excellent power factor can be improved by appropriately controlling the capacity of the phase advancing capacitor according to the power factor of the load.
It is possible to obtain an oil-filled transformer with a power factor correction device, which can effectively prevent the heat of the transformer from being transmitted to the power factor correction device and which has excellent operation reliability of the power factor correction device.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention, FIG. 2 is a circuit configuration diagram of the same, and FIG. 3 is a vertical sectional view of another embodiment. 1: Transformer body, 2: Power factor correction device, 3: Phase advancing capacitor,
4: Series reactor, 3.4: Power factor improving element, 5: Switching element,
8: Insulating oil, 9: Tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shozo Inakami 2-31 Tenma, Kita-ku, Osaka City, Osaka Prefecture Matsumura Gumi (share company) (72) Inventor Yasufumi Yuno 2-chome, Tenma, Kita-ku, Osaka-shi, Osaka No. 1-33 Matsumura-gumi, a stock company (56) References

Claims (1)

[Claims] 1. A transformer body comprising a star-connected primary winding, a delta-connected secondary winding and an iron core, and a delta connection connected in parallel with the secondary winding of the transformer body. In the oil-filled transformer with a power factor correction device having a phase advancing capacitor, a transformer main body and a tank for accommodating the phase advancing capacitor in a state of being immersed in insulating oil, a first capacitor, a first reactor, and a A first delta connection circuit in which the first power factor correction element is connected in a delta connection, which is formed by a series circuit of one thyristor, and a series circuit of a second capacitor, a second reactor, and a second thyristor. Second
The second delta connection circuit in which the power factor correction element of delta connection is connected, and the third power factor correction element configured by the series circuit of the third capacitor, the third reactor, and the third thyristor is connected in delta connection. Turn on the gates of the first thyristor, second thyristor and third thyristor by determining the power factor of the load by detecting the voltage and current on the secondary side of the transformer body and the delta connection circuit of 3 , A reactive power relay that supplies an OFF signal is provided, and the first delta connection circuit, the second delta connection circuit, and the third delta connection circuit are respectively connected in parallel with the secondary winding of the transformer body. In addition, the oil-filled transformer with a power factor improving device is arranged in the tank below the transformer body together with the phase-advancing capacitor, and the reactive power relay is arranged outside the tank. vessel.