JPS6018165B2 - multiphase power transport conductor - Google Patents

Description

[Detailed description of the invention] The present invention relates to multiphase power transport conductors.

Power transport conductors (such as phase-separated buses in multiphase power transport equipment)
A conductor (hereinafter abbreviated as "conductor") is covered with a metal jacket, the ends of each jacket are short-circuited between the jackets, a current of equal magnitude and opposite direction is induced in the conductor, the magnetic flux generated by the conductor is canceled out, and the magnetic flux generated by the conductor is canceled out. The configuration that eliminates leakage magnetic flux is called a mini-flux device, and this is shown in the diagrams: the oblique view of the three-phase separation bus in Figure 1, the explanatory diagrams of the mini-flux end in different states in Figures 2 and 3, and Figure 4. A front view cut along line A-A in FIG. 2 will be described. In the figure, 1 is a phase-separated bus bar, and conductors 2a, 2b,
2c are respectively covered with metal jackets 3a, 3b, 3c, and the three-phase jackets 3a, 3b, 3c are short-circuited at both ends by metal three-phase shorting plates 4, 4'.

When the three-phase conductors 2a, 2b, 2c transport symmetrical three-phase power, the jackets 3a, 3b, 3c are provided with shorting plates 4 at both ends.
, 4', the three phases are short-circuited, and a current almost equal to and opposite to that of the covering in-phase conductor is generated, and the conductor 2a
, 2b, 2c are canceled out. To further explain this, Fig. 2 shows the connecting part of the opposing mini-flux parts in a simplified side view when it is used mainly to cut off the vibration system or to escape thermal expansion and contraction in the phase separation bus, and 5a , 5b, 5c are boots with non-conductive potential, and the outer coverings 3a and 3a of the opposing mini-flux parts are
', 3b and 3b', and 3c and 3c', and there is no mini-flux between the mini-flux parts connected by boots 5a, 5b, and 5c.

Next, Figure 3 is a simplified side view of a phase-separated busbar used mainly for connection with connected equipment (transformers, generators, etc.), showing the mini-flux part and the connection part of devices and things using the mini-flux part. 2, 3a, 3b, and 3c are mini-flux parts as in FIG. 2, and 6a, 6b, and 6c are outer sheaths in which the three phases are not short-circuited.

FIG. 4 is a front view cut along the line A-A of FIG. 2 (or FIG. 3), which is used conventionally. 2a, 2b, 2c are conductors, 4 is a three-phase shorting plate, and 5 is a non-conductor. (However, in the case of FIG. 3, the jacket is not short-circuited in three phases when the mini-flux part M and the non-mini-flux part N are connected).

Although the conductors 2a, 2b, and 2c are shown as circles in the figure, they may be channels, a combination thereof, or square pipes, but the conductors generally have a uniform cross-section and a constant thickness.
However, as mentioned above, by short-circuiting the outside of each phase at the end phase, the current flowing in the jacket induces a current that is almost equal in magnitude and in the opposite direction to the conductor. Near the three-phase short-circuit plate, when the sheath current flows into or out of the three-phase short-circuit plate, it is biased toward the interphase side so that it flows over the shortest distance. In addition, the conductor current is given over to the bias of the sheathing current, and furthermore, when it comes off from the mini-flux part, it is induced by a pond phase (proximity effect).The situation at the moment is shown in Figures 2 and 3. The part shown by the solid line is the deviation of the jacket current, and the part shown by the broken line is the deviation of the conductor current. However, since the conductor in the aforementioned portion has a uniform current carrying cross-sectional area, the current density will be higher on the interphase side where the current is unbalanced than in other parts, and thermally
Due to the heat loss, a large thermal imbalance occurs, resulting in local overheating, and this phenomenon becomes more pronounced as the current increases.

As power transportation equipment increases in capacity, it is cooled by forced air cooling to suppress temperature rises, and when determining the cooling capacity, there are local overheating areas, and matching to these local overheating areas is difficult for other areas. Therefore, it is uneconomical. Furthermore, even in the case of self-cooling, providing a uniform cross-sectional area to suppress local heat generation is uneconomical since there is a large margin in areas where the current density is low. In consideration of these points, the present invention makes the cross-sectional area of the conductor non-uniform so that local overheating caused by current imbalance at the end of the mini-flux and the part outside the mini-flux can be prevented from occurring in other parts with a large margin. It is something that can be suppressed. FIG. 5 is a cross-sectional view of one embodiment of the conductor according to the present invention in a phase-separated bus bar, where 4 is a three-phase shorting plate as in FIGS. 1 to 4, and in the case of FIG. There is a non-conductive flexible boot jacket 5 in the case of partial connections, and in the case of FIG. 3 there is a jacket 6 connecting the mini-flux and non-mini-flux parts.
None of them are short-circuited. 11 is the opposing mini-flux connection part and the part removed from the mini-flux,
It is a conductor in which the plate thickness is partially thickened on the interphase side, that is, on the middle phase side at the end phase, and on the both end phase sides in the middle phase.

In this way, by increasing the plate thickness on the interphase side where the conductor current is biased, the cross-sectional area increases and local heat generation can be suppressed.

The polarity of the current varies depending on the shape of the conductor, the arrangement of equipment, etc., but it is most effective if the current density is kept constant depending on the polarity. In this case, a round conductor is shown, but the same applies to a channel, a combination thereof, or a square pipe conductor. A cutaway front view of another embodiment of the conductor according to the present invention is shown in FIG.

In this case, the interphase direction and the end phase are also provided with a conductor 12 partially cut out at the opposing mini-flux connection portion and the portion away from the mini-flux. Also, in the case of Figure 5, the thickness of the plate in the direction where the current is biased is increased to lower the current density, but in Figure 6, the conductive part in the direction where the current is biased is eliminated to scatter the current distribution. The thickness of the notched part needs to be thicker than that of the round conductor in the mini-flux part. In FIG. 6, both sides of the end phase are cut out, but only the middle phase side may be cut out. The three-phase phase separation bus bar has been described above as an example of the present invention.
It can also be effectively applied to multi-phase power transport equipment using a mini-flux structure, such as gas insulated switchyard (GIS) busbars.

Thus, when using the non-uniform cross-sectional conductor of the present invention, there is no need to pay attention to local overheating at the ends, and when increasing the capacity, forced cooling capacity can be determined by local overheating, or even in the case of self-cooling, it is not necessary to pay attention to local overheating at the ends. It is possible to eliminate the irrationality of having too much leeway. In the present invention, making the cross-sectional area at the end of the conductor non-uniform means changing the plate thickness of the conductor according to the current distribution so that the current density is constant in order to prevent local overheating due to unbalanced current. However, the thickness of the conductor plate is increased in areas where current is concentrated, the conductor is locally eliminated in areas where current concentration occurs, the current distribution is dispersed, and the thickness of the conductor plate is changed in multiple stages according to the current distribution. .

[Brief explanation of the drawing]

Figure 1 is a slope view of a three-phase phase separation bus, Figures 2 and 3 are explanatory diagrams showing the current flowing through the jacket and conductor under different usage conditions, and Figure 4 is the conventional diagram of Figure 2. FIGS. 5 and 6 are front views cut along the line A-A, and FIGS. 5 and 6 are front views cut along the line A-A of FIG. 2 of different embodiments of the present invention. In the figure, 2a, 2b, 2c are conductors, 3a, 3b, 3c, 3'
a, 3'b, 3'c are mini-flux jackets, 4 is a short circuit plate, 5a, 5b, 5c are boots without mini-flux jackets, 6a, 6b, 6c are 3-phase non-short circuit boards, 1
1 is the conductor part of the plate thickness, and 12 is the conductor part of the notch. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 In a multiphase power transport conductor covered with a metal jacket and short-circuited between each jacket, the cross-sectional area at the end of the conductor is made non-uniform, and the cross-sectional area of the conductor is made equal to that of the phase separation bus bar. A multiphase power transport conductor made by thickening the plates at the parts where current is concentrated, such as the middle phase side for the end phase and both end phase sides for the middle phase.