JPH0449325B2 - - Google Patents

Description

Detailed Description of the Invention A. Purpose of the Invention [Field of Industrial Application] The present invention provides a three-phase, four-wire circuit power supply for a dimmer, particularly a thyristor dimmer used for dimming stage lighting or studio lighting. This invention relates to a bus duct electrical circuit constructed of a close-contact type insulated bus duct.

[Conventional technology]

Dimmers using thyristors are commonly used for stage and studio lighting. As the power supply system, a 3-phase 4-wire electric circuit using a close-contact insulated bus duct is adopted in consideration of economic efficiency.

In a circuit using a thyristor dimmer, when the thyristor conducts and a current with a steep rise flows through the electrical circuit, the current of each of the three phases becomes a distorted waveform in which the sine wave is cut due to the dimming action. Each distorted waveform is accumulated in the neutral line, and the neutral line current increases, and the distorted waveform becomes completely different from a sine wave.

Due to the appearance of the above-mentioned abnormal distortion waveform, third, fifth, seventh, etc. odd harmonics are generated and give a shock to the electric circuit,
It is known that this shock wave induces magnetic and electrical vibrations, and as a result, the electric circuit itself vibrates and generates beats.

When a large current capacity bus duct is used as a circuit power source for a thyristor dimmer with the above characteristics, the bus duct is a 3-phase 4-wire closely-contact type insulated bus duct unit. The insulated conductor, which becomes the neutral wire among the four wires, is located outside the other three phase conductors R, S, and T, as indicated by the symbol N in Fig. 6, that is, the outermost one, and is It is in direct contact with the duct housing, which consists of other materials, and has a large capacitance with the ground.

Therefore, in addition to the characteristics of the thyristor dimmer, it also induces a distorted waveform, and the neutral line insulated conductor N
As the current accumulated in the conductor increases, the vibration of the conductor itself may generate violent beats (shock waves), causing a pollution problem.

Moreover, the load current consumed as the above-mentioned beat energy is large, and therefore the load current of each phase R, S, and T increases, creating a vicious cycle in which the voltage drop increases.

Measures to prevent the above-mentioned buzzing include (a) increasing the thickness of the duct housing to increase its mechanical strength;

(b) Narrow the support spacing of bus ducts to buildings, etc. and increase the number of fixing points.

(c) Make the duct housing of non-magnetic material such as aluminum.

(d) As shown in Figure 7, the length of the electrical circuit is divided into sections that are integral multiples of 3, and the conductors of the r, s, and t phases are swapped between the inside and outside for each appropriate section. The phases are twisted so that the lengths of the phase circuits are approximately equal.

We are taking measures such as:

[Problem that the invention seeks to solve]

In the conventional beat prevention measures mentioned above, (a) and
There are limits to the means for increasing the mechanical strength in item (b), and the following method (c) is not very effective considering that the beat is generated by the vibration of the conductor itself. In addition, each phase twisted frame in (d) has each phase r, s, and t.
The difference in inductance and capacitance of is eliminated, and 3
Although it is possible to prevent electrical unbalance such as voltage drop in each phase, as shown in Figure 7, the neutral conductor n is located at the outermost side in contact with the duct housing without being rearranged. ing.

Therefore, the electrical unbalance regarding the neutral conductor cannot be resolved by the conventional phase twisting system.

In view of the above problems, the present invention reduces the ground capacitance of the neutral line conductor to suppress the aftereffects of the load current on the neutral line conductor, and equalizes the load current of each phase conductor and the neutral line conductor. This prevents a significant voltage drop and suppresses humming. Furthermore, by suppressing the ground capacitance in each phase conductor, the purpose is to suppress beats that may occur from those conductors as well.

B. Structure of the Invention [Means for Solving Problems] In order to achieve the above object, the bus duct circuit of the present invention is a three-phase, four-wire, close-contact type insulated bus duct in which rectangular cross-section conductors each having an insulating coating are stacked on top of each other. In bus duct circuits that connect electrical equipment to each other through unit connections, the neutral wire insulated conductor in the intermediate bus duct circuit, except near the end where one end is connected to the electrical equipment, is separated from the duct housing. In this case, the insulated conductors of other phases are rearranged.

The present invention is also characterized in that an electrical insulator with a high dielectric constant is interposed between the duct housing and the outermost insulated conductor in the bus duct electrical path, and between each insulated conductor.

[Effect]

Because the neutral wire insulated conductor in the middle bus duct circuit, excluding the vicinity of both ends where the bus duct circuit is directly connected to electrical equipment, is separated from the duct housing, static electricity builds up between the neutral conductor and the ground. Capacity is significantly reduced.

Further, by interposing an electrical insulator with a high dielectric constant between the duct housing and the outermost insulated conductor and between each insulated conductor, the ground capacitance is further reduced.

〔Example〕

FIG. 1 shows the end face of a three-phase, four-wire, close-contact type insulated bus duct unit located in the middle of the bus duct circuit of the present invention. T) rectangular cross-section conductors 2, 3, 4 and a neutral wire N which is also insulated
The rectangular cross-sectional conductors 5 are stacked one on top of the other and are tightly housed in the duct housing 6.

Normally, the neutral conductor N of a 3-phase 4-wire close-contact type insulated bus duct unit is connected to the other 3-phase conductors R, S,
Although the bus duct unit is located outside the T, the bus duct unit located in the middle of the electric circuit of the present invention is located at the first
As shown in the figure, the neutral line conductor 5 is connected to conductor 2 and conductor 3.
By arranging the neutral line conductor 5 between the duct housing 6 and the duct housing 6, the neutral line conductor 5 is separated from the duct housing 6.

FIGS. 2 to 4 are circuit diagrams showing the bus duct electrical circuit of the present invention. Both ends of the electrical circuit formed by connecting any number of closely-contact type insulated bus duct units are
It is connected to each device on the power source (for example, main switchboard) side A and the load (for example, stage lighting panel) side B.

In the case of the example in Figure 2, the phase order of devices A and B connected to both ends of the bus duct circuit is the same,
In the bus duct units near both ends of the bus duct circuit (1st to 3rd from the equipment), by changing the positions of all the insulated conductors in the unit, the insulated conductor for the neutral line is moved away from the duct housing and moved inside. It is placed.

In the example in Figure 3, the phase order of devices A and B at both ends of the bus duct circuit is the same as in the example in Figure 2, and near both ends of the bus duct circuit (1 to 3 from the device)
In this bus duct unit, the R phase and S phase, and the T phase and neutral wire N are swapped, and the insulated conductor for the neutral wire is moved inside.
In this case, the R phase and the S phase may not be interchanged.

The example in Figure 4 shows equipment A and equipment at both ends of the bus duct electrical circuit.
If the phase order of B is reversed, change the positions of all insulated conductors in the bus duct unit near both ends of the bus duct circuit (1st to 3rd from the equipment) to match the phase order. By replacing them, the insulated conductor for the neutral wire is moved inside.

In each of the above embodiments, except for the vicinity of both ends of the bus duct circuit, the neutral line insulated conductor 5 (shown in the first diagram) located in the middle of the bus duct circuit is located inside the duct housing 6 without contacting it. ing.

FIG. 5 shows another embodiment of the close-contact type insulated bus duct unit used in the bus duct circuit of the present invention. An electrical insulator 7 having a high dielectric constant is interposed between the conductors 2, 3, 4, and 5, respectively.

As the high dielectric constant electric insulator 7, a synthetic resin film or sheet such as polypropylene, heat-resistant vinyl chloride, or polyimide is suitable.

C. Effects of the Invention In the bus duct electrical circuit of the present invention, the neutral line insulated conductor in the intermediate bus duct electrical circuit, excluding the vicinity of both ends directly connected to electrical equipment, is placed inside and away from the duct housing. The ground capacitance of the neutral line insulated conductor is significantly reduced, and the beat generated from the neutral line conductor is reduced. Therefore, the load current to the neutral conductor, which is consumed as beat energy, is reduced, and the voltage drop in each phase conductor is reduced.

In addition, high dielectric constant electrical insulators are interposed between the duct housing and the outermost insulated conductor, and between each insulated conductor, which further reduces the ground capacitance of each conductor and reduces the vibration of the conductor. This acts as a buffer material that absorbs the noise, further improving the effects of reducing the beat and voltage drop.

[Brief explanation of drawings]

FIG. 1 is an end view of a bus duct unit used in the intermediate portion of the bus duct electrical circuit according to the present invention, and FIGS. 2 to 4 are circuit diagrams of each embodiment of the electrical circuit according to the present invention.
FIG. 5 is an end view of a modification of the bus duct unit used in the electrical circuit of the present invention, and FIGS. 6 and 7 are circuit diagrams of conventional bus duct electrical circuits. 1 is an insulating coating, 2, 3, and 4 are R, S, and T phase conductors, 5 is a neutral line conductor, 6 is a duct housing, and 7 is a high dielectric constant electric insulator.

Claims (1)

[Scope of Claims] 1. In a bus duct circuit that connects electrical devices to each other by connecting three-phase, four-wire, close-contact type insulated bus duct units in which conductors with rectangular cross-sections each having an insulating coating are superimposed, one end is connected to the electrical device. A bus duct circuit characterized in that a neutral line insulated conductor in the intermediate bus duct circuit except near the end connected to the bus duct circuit is separated from the duct housing and rearranged between the insulated conductors of other phases. 2 In a bus duct circuit that connects electrical equipment to each other by connecting three-phase, four-wire, close-contact type insulated bus duct units in which conductors with rectangular cross-sections each having an insulating coating are stacked on top of each other, one end is connected to the electrical equipment. The neutral wire insulated conductor in the intermediate bus duct circuit except near the duct housing is relocated between the insulated conductors of the other phases, and the duct housing and the outermost insulated conductor in the bus duct circuit are separated from the duct housing. A bus duct electrical circuit characterized by interposing an electrical insulator with a high dielectric constant between the conductor and each insulated conductor.