JP2001244128A - Static induction electrical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a static induction electrical apparatus in which mechanical resonance of a magnetic shield is suppressed from occurring. SOLUTION: In the static induction electrical apparatus (e/g. a transformer), a winding wound around a core is contained in a transformer tank. A magnetic shield 4 is mounted on the inner wall of the transformer tank 3, opposite to the winding. The magnetic shield 4 is formed into a band where thin silicon steel plates are laminated. Intervals L of a plurality of metals 5 for fixing the magnetic shield 4 to the transformer tank 3 are set, such that the natural frequency of the magnetic shield 4 is higher than the frequency of a magnetic attraction acting thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static induction device, such as a transformer or a reactor, provided with a magnetic shielding device.

[0002]

2. Description of the Related Art Generally, in a stationary induction device such as a transformer or a reactor, an eddy current flows into a tank due to invasion of leakage magnetic flux from a winding and a lead wire, thereby causing a loss. This loss increases as the capacity increases, and a magnetic shielding device is usually provided in the tank to reduce the loss. As this magnetic shielding device, a magnetic shield in which a nonmagnetic material such as copper or aluminum or a silicon steel plate is laminated is generally used.

Various methods have been proposed for fixing such a magnetic shield. For example, in Japanese Utility Model Laid-Open No. 55-77827, among the silicon steel sheets constituting the magnetic shield, the width of a predetermined number of silicon steel sheets located on the tank side is made narrower than the width of other silicon steel sheets. Reduces the area for mounting fixtures,
It has been proposed to increase the rate at which the tank is covered with a magnetic shield. Further, Japanese Utility Model Laid-Open No. 57-115225 proposes a metal fitting for fixing a magnetic shield by staggering metal fittings having two claws so that adjacent magnetic shields can be fixed. ing.

[0004]

However, in the above-mentioned prior art, the magnetic shield is liable to cause mechanical resonance because sufficient consideration has not been given to the mounting interval of the fixture for fixing the magnetic shield. There is a problem. In other words, since the magnetic flux leaks from the windings and the lead wires penetrate into the magnetic shield, the operating frequency of 2
A magnetic attraction force having twice the frequency acts, and when the frequency matches the natural frequency of the magnetic shield, the magnetic shield causes mechanical resonance, generating noise, damaging the fixture, and the like.

Further, in the above-mentioned conventional technology, there is a problem that the temperature of the tank is locally increased because sufficient consideration is not given to the cooling of the magnetic shield and the tank. In other words, the loss in the magnetic shield is generally small, but if a large loss occurs partially in the tank on the back, the magnetic shield hinders cooling,
The temperature of the tank rises partly greatly.

It is a first object of the present invention to provide a highly reliable static induction device in which the magnetic shield suppresses mechanical resonance.

It is a second object of the present invention to provide a static induction device capable of suppressing a local rise in temperature of a tank.

[0008]

In order to achieve the first object, a stationary induction device of the present invention comprises an iron core, a winding wound on the iron core, and a tank containing the winding. A plurality of magnetic shields arranged on the inner wall of the tank so as to face the windings, and a distance between the plurality of fixing members for fixing the magnetic shield to the inner wall of the tank is different from that of the magnetic shield. It is characterized in that the frequency is set to be higher than the frequency of the magnetic attractive force acting on the magnetic shield.

The natural frequency of the magnetic shield varies depending on the distance between the fixed members. According to the above configuration, the interval between the fixing members is set so that the natural frequency of the magnetic shield is higher than the frequency of the magnetic attractive force acting on the magnetic shield. It can be suppressed.

[0010] In constituting the above stationary induction device,
The following elements can be added: (1) The fixing member has a plate shape bent in a crank shape, and one end is fixed to the inner wall of the tank and the other end is fixed to the surface of the magnetic shield. (2) The fixing member includes a flat base and two elongated plate-shaped locking portions provided with the base interposed therebetween, and the plate-shaped locking portions are bent in a crank shape and their tips are mutually separated. The base is fixed outward to the inner wall of the tank, and the plate-shaped locking part is fixed to the surface of the magnetic shield disposed adjacent to the tank. (3) The fixing member is a bolt inserted into a plurality of holes formed in the magnetic shield to fix the magnetic shield to the inner wall of the tank.

In order to achieve the second object,
The stationary induction electric device according to the present invention includes an iron core, a winding wound around the iron core, a tank storing the winding, and a plurality of magnetic bodies disposed on an inner wall of the tank so as to face the winding. A gap between the plurality of fixing members for fixing the magnetic shield to the tank inner wall is set such that the natural frequency of the magnetic shield is higher than the frequency of the magnetic attraction force acting on the magnetic shield. And a gap is formed between the magnetic shield and the inner wall of the tank.

According to the above configuration, the magnetic shield can be prevented from causing mechanical resonance, and the oil in the tank enters the gap between the magnetic shield and the tank, so that the tank is sufficiently cooled. Local temperature rise can be suppressed.

[0013] In constituting the stationary induction device,
The following elements can be added: (1) The fixing member has a substantially U-shaped plate shape, one end of which is fixed to the inner wall of the tank, and the other end of which is fixed to the surface of the magnetic shield, and depending on the thickness of the fixing member. The gap is formed. (2) The fixing member is a bolt inserted into a plurality of holes formed in the magnetic shield to fix the magnetic shield to the tank inner wall, and the magnetic shield and the tank inner wall. And a plurality of strips are provided between them, and the gaps are formed by the strips. (3) The strip is provided in a lateral direction of the tank. (4) The band plate is provided in a height direction of the tank.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a plan view showing an arrangement of a magnetic shield in a three-phase transformer, and FIG. 2 is a partially enlarged view of a state where the magnetic shield is fixed as viewed from a winding side. 1 and 2
In FIG. 1, a winding 2 is wound around a main leg (not shown) of the iron core 1, and the winding 2 is housed in a transformer tank 3 together with the iron core 1. On the inner wall of the transformer tank 3, a magnetic shield 4 formed by laminating a thin silicon steel plate is fixed by a fixing bracket 5 at a position facing the winding 2. The magnetic shield 4 has a band shape, and a plurality of magnetic shields 4 are provided along the height direction of the transformer tank 3. Although not shown in the figure, a fixing bracket 5 is also provided at the bottom of the magnetic shield 4.

FIG. 3 is a perspective view showing a state where the magnetic shield 4 is fixed by the fixing fitting 5. The fixing bracket 5 has a plate shape bent in a crank shape, one end of which is welded to the inner wall of the transformer tank 3, and the other end of which fixes the surface of the magnetic shield 4 (the surface on the side of the winding 2). ing. An intermediate portion of the fixing member 5 locks a side portion of the magnetic shield 4.

FIGS. 4A and 4B show dimensional specifications for examining the behavior of the magnetic shield. FIG. 4A is a view of the magnetic shield viewed from above, and FIG. FIG. The width of the magnetic shield 4 is W, the thickness is t,
Let L be the distance between the fixtures 5. The vibration in the magnetic shield 4 is approximately equal to the width W, the thickness t, and the length L.
Can be treated as vibration of an elastic body. The natural frequency (first-order mode) f of the elastic body fixed at both ends and placed in oil
Is represented by the following equation.

[0017]

(Equation 1) Here, γ: frequency reduction ratio in oil λ: constant ρ: density of the magnetic shield E: Young's modulus of the magnetic shield

FIG. 5 is a graph showing the relationship between the spacing L between the fixtures and the natural frequency of the magnetic shield. In the figure, the broken line indicates the frequency of the magnetic attractive force acting on the magnetic shield. The natural frequency tends to decrease as the distance L increases and as the magnetic shield decreases.
Increasing the distance L between the fixtures can reduce the number of fixtures, so that the natural frequency of the magnetic shield is larger than the frequency of the magnetic attraction force acting on the magnetic shield. If the distance L is increased, the magnetic shield can be economically fixed without causing mechanical resonance. In the present embodiment,
The distance L between the fixing brackets is fixed, but L
It is also possible to change. In that case, the natural frequency may be evaluated for the maximum interval L.

(Embodiment 2) FIG. 6 shows Embodiment 2 of the present invention, and is a partially enlarged view of a state in which a magnetic shield is fixed as viewed from a winding side. In the present embodiment, 2
Using two fixed fittings 6 in which two fixing fittings are integrated,
Two adjacent magnetic shields 4 are fixed. 2
The interval L between the continuous fixtures 2 is selected such that the natural frequency of the magnetic shield 4 is maximized in a range larger than the frequency of the magnetic attractive force acting on the magnetic shield 4.

With this configuration, it is possible to suppress the occurrence of mechanical resonance in the magnetic shield 4 as in the first embodiment. Further, in the present embodiment, there is an effect that the number of fixing brackets can be reduced by almost half compared to the first embodiment.

(Embodiment 3) FIG. 7 shows Embodiment 3 of the present invention, and is a partially enlarged view of a state in which a magnetic shield is fixed as viewed from a winding side. In the present embodiment, bolts are used as fixing members. That is, a magnetic shield with holes 9 having a plurality of holes formed in advance in the longitudinal direction is arranged on the inner wall of the transformer tank 3, and the magnetic shield 9 with holes is formed by bolts 10 inserted through the holes.
Are fixed to the inner wall of the transformer tank 3. The distance between the holes formed in the magnetic shield 9 with holes is L, and the bolt 10
The distance between the bolt 10 is also L. The distance L between the bolts is selected such that the natural frequency of the magnetic shield 9 with holes is maximized in a range larger than the frequency of the magnetic attractive force acting on the magnetic shield 9 with holes.

With this configuration, it is possible to suppress the occurrence of mechanical resonance in the magnetic shield 9 having holes, as in the first embodiment.

(Embodiment 4) FIGS. 8A and 8B show Embodiment 4 of the present invention, and FIG. 8A is a partially enlarged view of a state in which a magnetic shield is fixed, viewed from the winding side, and FIG. () Is a cross-sectional view along the line AA in (a). In the present embodiment, the magnetic shield 4 is fixed to the inner wall of the transformer tank 3 by the fixing bracket 7 with a base. As shown in FIG. 9, the mounting bracket 7 with a pedestal has a substantially U-shaped plate shape, one end of which is welded to the inner wall of the transformer tank 3, and the other end of which is a surface ( (Surface on the winding 2 side). An intermediate portion of the mounting bracket 7 with the pedestal locks a side portion of the magnetic shield 4. The distance L between the pedestal-attached fixing members 7 is selected so that the natural frequency of the magnetic shield 4 is maximized in a range larger than the frequency of the magnetic attractive force acting on the magnetic shield 4.

With this configuration, it is possible to suppress the occurrence of mechanical resonance in the magnetic shield 4 as in the case of the first embodiment.

Further, since the oil gap 20 is formed between the inner wall of the transformer tank 3 and the magnetic shield 4 by the one end 7A of the mounting bracket 7 with the base, a large amount of heat is generated in a part of the transformer tank 3. Even in such a case, sufficient cooling becomes possible, and a rise in the temperature of the transformer tank 3 can be prevented.

(Embodiment 5) In the case where the magnetic shield is fixed by the mounting bracket with a base, as shown in FIG.
A series of fixtures can be used. That is, FIG.
As described above, the use of the pedestal-attached fixing bracket 8 in which two pedestal-attached fixing brackets are integrated makes it possible to fix adjacent magnetic shields.

As shown in FIG. 11, cuts 8B are provided on both sides of the flat plate 8A, and two pedestal units each having an elongated plate-shaped locking portion 8C formed by the cuts 8B and bent in an inverted L-shape. Even if the fixing bracket 8 'is used,
Adjacent magnetic shields can be fixed.

In the case where the above-mentioned pedestal-attached double mounting bracket 8 or 8 'is used, the distance L between the mounting brackets is determined by the natural frequency of the magnetic shield and the frequency of the magnetic attraction force acting on the magnetic shield. In the larger range, you need to choose the largest. Further, with this configuration, similarly to the first embodiment, it is possible to suppress the occurrence of mechanical resonance in the magnetic shield.

Further, a double fixture 8 or 8 'with a pedestal.
Accordingly, an oil gap is formed between the inner wall of the transformer tank and the magnetic shield, so that the transformer tank can be sufficiently cooled and a rise in the temperature of the transformer tank can be prevented. In addition, if the pedestal-attached double fixing bracket 8 or 8 ′ is provided, the number of fixing brackets can be reduced by almost half compared to the case of the fourth embodiment.

(Embodiment 6) FIG. 12 shows Embodiment 6 of the present invention, and is a partially enlarged view of a state in which a magnetic shield is fixed as viewed from a winding side. In the present embodiment,
A plurality of horizontal mounting seats 11 having screw holes formed in advance are welded at predetermined intervals along the lateral direction of the tank. A plurality of holes are formed in the magnetic shield 9 with holes, corresponding to the positions of the horizontally arranged mounting seats 11. Then, bolts 10 are inserted into the holes of the magnetic shield 9 with holes and the holes of the horizontal mounting seat 11, and the magnetic shield 9 with holes is fixed to the inner wall of the transformer tank with the horizontal mounting seat 11 sandwiched therebetween. ing.

Also in this embodiment, the distance L between the bolts 10 in the magnetic shield 9 with holes is determined by the fact that the natural frequency of the magnetic shield 9 with holes is equal to the frequency of the magnetic attractive force acting on the magnetic shield 9 with holes. It is chosen to be the largest in a large range.

With this configuration, it is possible to suppress the occurrence of mechanical resonance in the magnetic shield. further,
Since an oil gap is formed between the magnetic shield with holes 9 and the transformer tank 3, an increase in the temperature of the transformer tank 3 can be suppressed.

(Embodiment 7) FIG. 13 shows Embodiment 7 of the present invention, and is a partially enlarged view of a state in which a magnetic shield is fixed, as viewed from a winding side. In the present embodiment,
A plurality of vertically arranged mounting seats 12 each having a threaded hole are welded at predetermined intervals along the tank height direction. A magnetic shield 9 with holes is fixed to each of the vertically arranged mounting seats 12 with bolts 10.

The distance L between the bolts of the magnetic shield 9 with a hole is set to be the most within a range where the natural frequency of the magnetic shield 9 with a hole is larger than the frequency of the magnetic attraction force acting on the magnetic shield 9 with a hole. I chose to be bigger. According to the present embodiment, the same effect as in the case of the sixth embodiment can be obtained.

[0035]

As described above, according to the present invention,
Since the occurrence of mechanical resonance of the magnetic shield is suppressed, there is no generation of noise or damage to the fixed member, and a highly reliable stationary induction device can be realized.

Further, since an oil gap is formed between the magnetic shield and the tank, the tank is sufficiently cooled and a local rise in the temperature of the tank can be suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view of a stationary induction device.

FIG. 2 shows the first embodiment of the present invention and is a partially enlarged view of a state in which a magnetic shield is fixed, as viewed from a winding side.

FIG. 3 is a perspective view showing a magnetic shield fixed with a fixing bracket.

4A and 4B show a magnetic shield fixed by a fixing bracket, wherein FIG. 4A is a plan view and FIG. 4B is a side view as viewed from a winding side.

FIG. 5 is a diagram showing a relationship between a spacing between fixing brackets and a natural frequency of a magnetic shield.

FIG. 6 shows the second embodiment of the present invention and is a partially enlarged view of a state in which a magnetic shield is fixed, as viewed from a winding side.

FIG. 7 shows the third embodiment of the present invention, and is a partially enlarged view of a state where the magnetic shield is fixed, as viewed from the winding side.

8A and 8B show a fourth embodiment of the present invention, in which FIG. 8A is a partially enlarged view of a state in which a magnetic shield is fixed, viewed from the winding side, and FIG. 8B is an AA line of FIG. FIG.

FIG. 9 is a perspective view showing a magnetic shield fixed with a mounting bracket with a base.

FIG. 10 shows the fifth embodiment of the present invention, and is a perspective view showing an example of a double fixing bracket with a pedestal.

FIG. 11 is a perspective view showing another example of a double fixture with a pedestal.

FIG. 12 shows the sixth embodiment of the present invention, and is a perspective view of a main part when a state where a magnetic shield is fixed is viewed from a winding side.

FIG. 13 shows the seventh embodiment of the present invention, and is a perspective view of a main part in a state where a magnetic shield is fixed, as viewed from a winding side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron core 2 Winding 3 Transformer tank 4 Magnetic shield 5 Fixing bracket 6 Double fixing bracket 7 Pedestal fixing bracket 8, 8 'Double fixing bracket with pedestal 9 Magnetic shield with hole 10 Bolt 11 Horizontal mounting seat 12 Vertical mounting seat

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Noriyuki Uchiyama 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Power & Electric Development Laboratory, Hitachi, Ltd. (72) Inventor Masanori Mitsui Kokubu, Hitachi City, Ibaraki Prefecture 1-1-1, Machi, Kokubu Office, Hitachi, Ltd. (72) Inventor Shoichi Yamamoto 1-1-1, Kokubuncho, Hitachi, Ibaraki, Japan 1-1-1 Kokubuncho, Hitachi City F-term in Kokubu Office, Hitachi, Ltd. F-term (reference) 5E043 AA02 AB01 EA05 EA08 5E058 CC23 CC25 CC29

Claims (9)

[Claims] 1. An iron core, a winding wound around the iron core, a tank storing the winding, and a plurality of magnetic shields disposed on an inner wall of the tank so as to face the winding. The distance between the plurality of fixing members for fixing the magnetic shield to the tank inner wall is set such that the natural frequency of the magnetic shield is higher than the frequency of the magnetic attraction force acting on the magnetic shield. A static induction device characterized by the following. 2. The stationary induction device according to claim 1, wherein the fixing member has a plate shape bent in a crank shape, and one end is on the inner wall of the tank and the other end is on the surface of the magnetic shield. A stationary induction device characterized by being fixed. 3. The stationary induction device according to claim 2, wherein the fixing member includes a flat base and two elongated flat locking portions provided on both sides of the flat base. The locking portion is bent in a crank shape and the tips are formed outwardly from each other, the base portion is on the inner wall of the tank, and the plate-shaped locking portion is on the surface of the magnetic shield, which is disposed adjacent to the tank. A stationary induction device characterized by being fixed respectively. 4. The stationary induction device according to claim 1, wherein the fixing member is inserted through a plurality of holes formed in the magnetic shield to fix the magnetic shield to an inner wall of the tank. A static induction device characterized in that it is a bolt. 5. An iron core, a winding wound around the iron core, a tank storing the winding, and a plurality of magnetic shields disposed on an inner wall of the tank so as to face the winding. The interval between the plurality of fixing members for fixing the magnetic shield to the tank inner wall is set such that the natural frequency of the magnetic shield is higher than the frequency of magnetic attraction acting on the magnetic shield, and And a gap is formed between the magnetic shield and the inner wall of the tank. 6. The stationary induction electric device according to claim 5, wherein the fixing member has a substantially U-shaped bent plate shape, one end of which is on the inner wall of the tank, and the other end of which is a surface of the magnetic shield. Wherein the gap is formed by the thickness of the fixing member. 7. The stationary induction device according to claim 5, wherein the fixing member is inserted through a plurality of holes formed in the magnetic shield to fix the magnetic shield to the inner wall of the tank. The stationary induction electric appliance, wherein a plurality of strips are provided between the magnetic shield and the inner wall of the tank in addition to the bolts, and the gaps are formed by the strips. 8. The static induction device according to claim 7, wherein the strip is provided in a lateral direction of the tank. 9. The static induction device according to claim 7, wherein the strip is provided in a height direction of the tank.