JPS5818274Y2 - Denki Kiki no Reiki Yakusouchi - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a cooling device for electrical equipment that can effectively cool a tank housing the electrical equipment.

Figure 1 shows a conventional cooling system for electrical equipment, where 1 indicates electrical equipment 2.
3 is a circulation device that circulates the cooling oil 4 in the tank 2 through a connecting pipe 5 and a cooler 6, and 7 is a bushing that electrically connects the electric equipment 2 and the outside of the tank 1.

When the electrical equipment 2 becomes energized and current flows through the bushing 1, the bushing 1 is placed near the bushing 7 of the tank 1.
An eddy current flows under the influence of the generated magnetic field, and when the amount of current in the bushing 7 increases, heat is generated in the vicinity of the bushing 7 of the tank 1.

For this reason, in the conventional type, as shown in the figure, a circulation port 8 for the cooling oil 4 is provided near the bushing 7, and the flow rate of the cooling oil 4 near the bushing is increased to enhance the cooling effect.

However, in such a structure, there is a large amount of cooling oil 4 that moves directly from the center of the tank 1 toward the circulation port 8, and a sufficient flow rate cannot be obtained, especially on the opposite side of the bushing 7 from the circulation port 8. There was a risk of overheating.

This idea was made in view of the above points, and by arranging a partition wall inside the tank near the bushing to increase the flow velocity of the cooling medium near the bushing, and forming this partition wall with a good conductor, the above-mentioned The object is to provide a cooling device for electrical equipment that is free from drawbacks.

An embodiment of this invention shown in FIGS. 2 to 4 will be described below.

In the figure, since 1 to 8 are the same as the conventional one, explanations thereof will be omitted.

Reference numeral 9 denotes a wall surface formed in a convex shape near the penetration portion of the bushing 7 of the tank 1, and 10 a partition wall made of a good conductor, forming an oil passage 11 between the partition wall 9 and the wall surface 9.

12 is a gap formed between the partition wall 10 and the bushing 1, and 13 is an opening provided in the partition wall 10.

When the circulation device 3 operates, the cooling oil 4 in the tank 1 is circulated from the gap 12 or opening 13 to the oil path 11 - circulation port 8 - connection pipe 5 - cooling device 6 - circulation device 3 - connection pipe 5 - tank 1. do.

The cooling oil 4 flows as indicated by the arrow, and the flow velocity near the bushing is high even on the opposite side of the circulation port 8.

The flow rate of the cooling oil 4 can be arbitrarily adjusted by selecting the width of the gap 12 or the distance between the wall surface 9 and the partition wall 10.

On the other hand, looking at the problem of heat generation in the tank 1, eddy currents flow in the tank 1 due to the influence of the magnetic field generated by the current flowing through the bushing 7, causing heat generation, but this is because the partition wall 10 is made of a good conductor. , an eddy current that generates a reaction magnetic flux in a direction that cancels the magnetic flux generated by the current flowing through the bushing 7 flows through the partition wall 10, and works to cancel the influence of the magnetic field generated by the bushing current on the tank 1. , the amount of heat generated near the bushing 7 of the tank 1 decreases.

That is, by decomposing the current vector as shown in Fig. 5, the symmetrical three-phase currents ■U, ■■, ■W4 flowing through the bushing 1 shown in Figs. A set of reciprocating currents that circulates as IURIIWR, and an IUI that reciprocates between both end phases with a phase difference of 90° from these.
It can be decomposed into two sets of reciprocating currents: a set of reciprocating currents in the tIW process.

Then, the magnetic field created by each set of these reciprocating currents (
When the opening part is viewed from above, if there is no partition wall 10, φR2φ■ (which can also be called magnetic flux) would be perpendicular to the vertical plane of the convex tank wall surface 9, as shown in FIG. It will pass through.

Note that FIG. 6a shows the magnetic field generated by the reciprocating current IV IURjIWR, and FIG. 6 shows the generation of the magnetic field due to the reciprocating current IUIjIWI.

Therefore, eddy current and resulting eddy current loss occur on the tank wall surface a.

Therefore, it is often difficult to sufficiently suppress the temperature rise simply by providing a convex portion on the outlet portion and, for example, a partition made of an insulating material to improve the oil flow.

By the way, since the partition wall 10 of the present invention, which is a good conductor, is placed inside the tank wall 9, the magnetic flux due to the bushing current penetrates the partition wall 10 of the present invention, and an eddy current flows therethrough, as described above.

The magnetic flux distribution of each phase is different due to the difference in magnetic flux distribution, but the most severe phase will be described.

As shown in FIG. 6, the magnetic flux φR originally has a large component along the partition wall and a small component penetrating the partition wall.

Therefore, the eddy currents ■R and ■8 caused by this
The reaction magnetic flux φR caused by is relatively small as shown in FIG. 7a.

On the other hand, the component of the magnetic flux φ■ in the direction penetrating the partition wall 10 ceases, and a thick eddy current ■■ flows as shown in FIG. 7, generating a reaction magnetic flux φ1.

Therefore, it can be said that the magnitude of the eddy current and the generated loss are determined by the magnetic flux φI.

The current due to this φ1 is larger than the current flowing through the tank wall 9 when the partition wall 10 is not present, but since the resistance of the material of the partition wall 10 is sufficiently lower than that of the material used for the tank wall a, the generated loss is small. .

In other words, the loss caused by eddy current is II=E/IZI (
1) Z=r+jx, 1Z1=JITmer ---
[2) W = rI■2 = rE2/(r2+x2) −
...C3) However, ■■: Eddy current, Z: Impedance of the circuit through which the eddy current flows, r: Resistance of the circuit, X: Reactance due to inductance of the circuit, W: Generated loss.

Since the resistance of the barrier 10, which is a good conductor, is generally small and r<x, the loss in equation (2) is calculated by ignoring r with respect to
From, W=rE2/(r2+x”)”: rE2/
x2ocr - [4,], and the smaller the resistance r, the smaller the generated loss.

The case where the current value is almost determined by the actance of the circuit is called a reactance limited circuit, and the present invention corresponds to such a case.

Therefore, even though a large current flows through the bulkhead 10, the loss generated therein is small, and a large reaction magnetic flux φ■/ is effectively generated. The magnetic field will also become smaller and losses will be drastically reduced.

In addition, the eddy current distribution is as shown in Figure 7.
A and brim 10b are effectively used to construct an effective loop circuit.

Further, the top plate 10a and the collar 10b also have the role of improving oil flow distribution.

The above explanation has been made for the case where the tank wall surface 9 of the bushing 7 penetration part is formed in a convex shape, but it is not necessary to form it in a convex shape. If the tank wall is provided with a wall through which the conductor passes, it can be expected to prevent heat generation in the tank and improve the cooling effect, as in the case described above.

Furthermore, as shown in FIGS. 8 to 10, it goes without saying that the same effect can be obtained even if a partition wall in which three phases are integrated is provided.

That is, even in the case of the tank wall 9 having three-phase convex portions, the magnetic flux produced by the bushing 7 is the same as in the case of FIGS. 2 to 4, and is as shown in FIG. 11.

Note that FIG. 11a shows the magnetic field generated by the reciprocating currents ■■-■U□ and ■wR, and FIG.

However, in this case, since the tank wall 9 and the good conductor partition wall 10 inside it surround the three-phase body, not only the magnetic flux φ□ but also most of the magnetic flux φ□ penetrates them, causing a large eddy current. will occur.

As a result, reaction magnetic fluxes φ,', φ□' are generated in the same way as in the previous case.

If this is shown in a schematic diagram, it will be as shown in FIGS. 12a and 12b.

In this case, although the magnetic flux orthogonal to the partition wall 10 is large, since the partition wall 10 is in one piece, the eddy current path is determined to be distributed in a manner that effectively generates a reaction magnetic velocity.

This is due to electromagnetic properties.

Therefore, the reduction in orthogonal magnetic flux and loss due to the provision of the partition wall 10 becomes even more remarkable.

13 to 16 are analytical data for explaining the effects of the present invention, and under the following conditions, the convex tank wall 9
And the distribution of the orthogonal magnetic flux density and the generated loss density of the partition wall 10 is obtained.

Tank protrusion material Non-magnetic steel SUS 304 Partition wall material
Dimension between aluminum phases: 1200 mm Frequency: 60 Hz Figures 13 and 14 show the magnetic flux density distribution and loss density distribution at the individual protrusion of each phase shown in Figures 2 to 4, and Figures 15 and 16 show the The magnetic flux density distribution and loss density distribution in the three-phase convex portion shown in FIGS. 8 to 10 are shown.

13 and 15, the solid line shows the magnetic flux density distribution of the protruding tank wall 9 without the aluminum partition 10, and the broken line shows the magnetic flux density distribution of the protruding tank wall 9 with the aluminum partition 10. ing.

In addition, in FIGS. 14 and 16, the solid line indicates the partition wall 10.
In the case where there is no partition wall 10, the broken line shows the loss density distribution in the tank wall 9 when there is the partition wall 10, and the dashed line shows the loss density distribution in the partition wall 10.

Moreover, the horizontal axis of each figure is shown in correspondence with the position of each part of the tank wall 9 and the partition wall 10 shown in the upper part of each figure.

Note that the magnetic flux density and loss density are scaled using the same scale in both cases.

If you look at each graph, it is obvious that the effect of partition walls made of good conductors on both the orthogonal magnetic flux density distribution and the loss density distribution is obvious. However, to add a few points, the orthogonal magnetic flux density distribution and the loss density distribution are ,
The reason why the U phase and W phase are asymmetric is that the phase order is U.

The reason for this is that the bushing current is a three-phase symmetrical current, whereas the bulkhead current flows in unison with the magnetic field of each phase depending on its inductance and resistance. This is a phenomenon that occurs.

2. Although the analysis correctly takes into account the phase as described above, for convenience, the graph of the magnetic flux distribution shows only the absolute value.

In the above explanation, we have explained the case of a three-phase transformer, but since a single-phase transformer usually has a reciprocating through-hole configuration, the generated magnetic flux φ has a large distribution in the middle between the U and V terminals. Although eddy currents are generated in the tank walls, providing a partition wall with good conductivity can have a significant loss reduction effect in this case as well.

In addition, the distribution of magnetic flux φ in this case is the same as the magnetic field due to the reciprocating current ■U□−■Y in Figure 6, and there is only a penetrating part in the part corresponding to the ■phase, and the U phase and W As mentioned above, partition walls made of good conductor have a great effect on phase penetration parts.

As described above, the cooling device for electrical equipment of this invention has the effect that the flow rate of the cooling medium near the bushing is high and the heat generation of the tank 1 is suppressed by the partition wall, so there is little risk of the tank overheating. It is the same as the magnetic field due to the reciprocating current IUI-I in Figure 6, and there is no penetration part in the part corresponding to the ■ phase, but the U phase,
As described above, a partition wall made of a good conductor has a great effect on the W-phase penetration portion.

[Brief explanation of the drawing]

Figure 1 is a simplified cross-sectional view of a conventional cooling device for electrical equipment;
Figures 4 to 4 show a cooling device for electrical equipment according to an embodiment of this invention, with Figure 2 being a plan view thereof, and Figure 3 being a simplified vertical sectional view thereof.
Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3, Figure 5 is a vector diagram of symmetrical three-phase current, Figure 6 a, b is a distribution diagram of the magnetic field due to bushing current, Figure 1 a, t). is a distribution diagram of a thin current in the partition wall, FIGS. 8 to 10 show other embodiments of this invention, FIG. 8 is a plan view, FIG. 9 is a longitudinal sectional view, and FIG. Cross-sectional view along line X-X, Figure 11a
, b are distribution diagrams of the magnetic field due to the bushing current in Figures 8 to 10, Figures 12a and b are distribution diagrams of the eddy current of the partition wall in Figures 8 to 10, and Figures 13 and 15 are Figures 14 and 16 are loss density distribution diagrams of the tank wall. In the figure, 1 is a tank, 2 is an electric device, 3 is a circulation system, 4 is a cooling oil, 6 is a cooler, 7 is a bushing, 9 is a wall surface, and 10 is a partition wall. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A tank that stores electrical equipment and a cooling medium for cooling the electrical equipment, a conductor that passes through the tank and is connected to the electrical equipment, and a conductor that passes through the tank and is arranged opposite to the inside of the wall near the conductor of the tank. 1. A cooling device for electrical equipment, comprising a partition wall provided therein, a cooling medium circulation device for circulating the cooling medium between the partition wall and the wall surface, and the partition wall is made of a good conductor.