JP2007142341A - Heat radiating structure of thunder resistance reinforcing type insulation transformer for low voltage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiating structure capable of easily reducing the size, weight and thickness of a thunder resistance reinforcing type insulation transformer for a low voltage. <P>SOLUTION: A lead leading-out section 13 for leading out primary lead wires 3a, 3b of a primary winding 3 to the outside of the case is formed on an insulation case 10 for covering the entire surface of a ring body 4 in which the primary winding 3 is wound around a ring-like winding iron core 1 via a second insulator 2, and a heat radiating cylinder 16 and an ambient air intake cylinder 18 are formed in an axial direction on the external interference of the insulation case 10. A heat radiating port 15 of the heat radiating cylinder 16 and an ambient air intake port 17 of the ambient air intake cylinder 18 are allowed to communicate with a gap G between the ring body 4 and the insulation case 10, heat generated from the ring body 4 is radiated to the outside of the case to suppress the temperature rise of the primary winding 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat dissipation structure in a lightning proof strengthening type low voltage insulation transformer used for power supply systems of various electric facilities and electric devices.

  Lightning-proof enhanced low-voltage insulation transformers (lightning-resistant transformers) are required to have high performance through low loss, high withstand voltage, and improved surge attenuation. The demand for this is increasing year by year. There is a contradictory relationship between the high-voltage withstand voltage and surge attenuation in this insulated transformer and the small size and light weight of the transformer itself, and it is technically difficult to realize both at the same time. .

For example, a ring core type insulation transformer in which a primary winding is wound around a ring-shaped iron core, the primary winding is covered with an insulating case and electrostatic shielding is performed, and then the secondary winding is wound around the insulating case Is known as a small power transformer (see, for example, Patent Document 1).
Japanese Patent Application Laid-Open No. 06-5437

  In the above ring core type insulation transformer, the primary winding wound around the iron core is covered with an insulation case, so heat is trapped inside the case and the temperature rise of the primary winding becomes a problem. The amount of current used is extremely small, and the temperature rise of the primary winding is small, so that there is almost no problem. However, when used as an insulation transformer for lightning protection type low voltage, the temperature rise of the primary winding increases, so use a winding with a large wire diameter to keep the current density low and the temperature rise of the primary winding low. It is designed to be. However, this causes a problem that the transformer itself becomes large and increases in weight, and it is difficult to reduce the size and weight of the lightning proof type low voltage insulation transformer. In addition, lightning strengthened low-voltage insulation transformers are highly demanded to be thin enough to be wall-mounted and pillar-mounted, but at present they cannot meet the demand for thinness due to the increase in size. is there.

  An object of the present invention is to provide a heat dissipation structure that facilitates reduction in size and weight of a lightning proof strengthening low-voltage insulation transformer.

  The present invention relates to a ring body in which a primary winding is wound on a ring-shaped wound core through a first insulator attached to the entire surface of the wound core, and a high-voltage insulation covering the entire surface of the ring body. A ring-shaped insulating case having a lead lead-out portion for partially leading the primary lead wire of the primary winding to the outside, and a secondary winding wound around the insulating case. A heat dissipation structure for a lightning proof type low-voltage insulation transformer, and the insulation case is provided with a heat release port that communicates with the gap between the insulation case and the ring body to release the heat generated by the ring body outside the case. It is characterized by.

  Here, as the wound iron core, a directional silicon steel sheet having a small magnetic resistance and a high magnetic flux density wound in multiple layers can be used. The first insulator deposited on the entire surface of the wound core is a thin coating film or insulating tape that does not damage the first winding. A small ring body is formed by further winding a primary winding around a wound iron core. The insulating case that covers the entire surface of the ring body is a resin molded product or rubber case that facilitates high-voltage insulation, and specifically, a pair of ring shapes that are detachably fitted from both axial end surfaces of the ring body. It is composed of a first case and a ring-shaped second case, and when it is put on the ring body, a gap mainly composed of a line gap of the primary winding is formed between the case inner surface and the ring body. The outer surface of the insulating case is subjected to electrostatic shielding treatment, and the secondary winding is wound on the outer surface of the insulating case excluding the lead lead-out portion. On the outer surface including the lead lead-out portion of the insulating case, a heat radiation port is formed at a single portion or a plurality of locations on the outer surface where the secondary winding is not wound. The heat radiation port communicates with a gap between the inner surface of the insulating case and the ring body, and radiates heat generated in the ring body to the outside of the case. Although the formation position of the heat radiation port in the insulating case is not limited, it is selected at a position where the heat radiation performance is not impaired by being blocked by a transformer mounting member or the like. The temperature rise of the primary winding is suppressed by heat dissipation in the insulating case, and it becomes easy to reduce the wire diameter of the primary winding to make the ring body and the transformer itself small.

  The heat radiating port of the insulating case can be a heat radiating tube protruding in the radial direction from the outer periphery of the ring-shaped insulating case. Such a radiating cylinder makes it easy to reduce the thickness of the transformer itself by reducing the axial height of the ring-shaped insulating case. Further, the heat radiating port of the insulating case may be a heat radiating tube protruding in the axial direction from one end surface of both end surfaces in the axial direction of the ring-shaped insulating case. In this case, the insulating case is arranged so that the one end surface from which the heat radiating tube of the insulating case protrudes becomes the upper surface, so that the heat dissipation from the upper surface is enhanced.

  In the present invention, the primary lead wire led out from the tip of the lead lead-out portion of the insulating case is covered with a flexible insulating cylinder, and communicates with the heat radiation port between the insulating cylinder and the primary lead wire. It can be set as the structure which formed the thermal radiation gap. The flexible insulating cylinder here may be a rubber tube having a length from the tip of the lead lead-out portion to the terminal conductor portion formed at the tip of the primary lead wire. The insulating cylinder and the leading end of the lead lead-out portion are insulatively coated with an insulating tape or the like as necessary. Such an insulating cylinder is bent together with the primary lead wire to facilitate wiring connection of the primary lead wire and the heat radiation gap between the insulating cylinder and the primary lead wire enhances the heat dissipation in the insulating case. Further, when the lead lead-out portion is formed to protrude in the radial direction from the outer periphery of the ring-shaped insulating case, the protruding length can be shortened by the amount of the insulating cylinder.

  Moreover, in this invention, it can be set as the structure which has the lead | lead derivation | leading-out heat radiation cylinder part which has both the insertion hole of a primary lead wire, and a heat radiating port in the lead | lead lead-out part of an insulation case. In this case, the lead lead-out portion also serves as the heat radiating port and the heat radiating cylinder. In other words, the heat radiating port and the heat radiating cylinder provided in the insulating case also serve as the lead derivation portion. By doing so, the lead lead-out portion of the insulating case, the heat radiating port, and the heat radiating tube can be formed at the same place, and the design and manufacture of the insulating case becomes easy. Also, by projecting the lead lead-out and heat radiating cylinder part of the lead lead-out part radially from the outer periphery of the insulating case, this heat radiating cylinder part is connected to the primary lead wire, the primary winding, and the secondary winding around the insulating case. Insulate to make it easy to secure the insulation distance between the two windings.

Moreover, in this invention, the external air intake port connected to a heat radiating port can be formed in the part away from the heat radiating port of the insulation case. The outside air intake port may be an outside air intake cylinder that protrudes in the radial direction from the outer periphery of the ring-shaped insulating case.

  Here, the outside air intake can be formed at any single location or multiple locations of the insulating case. By forming the outside air intake port and the outside air intake tube together with the heat radiating port together with the heat radiating port in the insulating case, the air flow in the insulating case is smoothed and the heat radiation is improved.

  According to the present invention, the heat radiating port and the heat radiating tube provided in the insulating case covering the primary winding wound around the wound iron core act so as to suppress the temperature rise in the case to a low level. Winding resistance and copper loss can be reduced, and the outer diameter of the ring body is reduced by reducing the wire diameter of the winding, miniaturizing the transformer itself, and suppressing the temperature rise and high performance The excellent effect that it can be made can be produced.

  In addition, by projecting the heat radiating cylinder and lead lead-out portion in the radial direction from the outer periphery of the ring-shaped insulating case, the insulating case and the transformer itself in which the secondary winding is wound around the insulating case can be thinned. It is possible to provide a lightning proof strengthening type low-voltage insulation transformer that has a high practical value as a wall-mounted type or a column type.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  1 and 2, the lightning strengthened low-voltage insulation transformer covers the entire surface of a ring-shaped wound core 1 with a first insulator 2, and the primary winding is wound around the wound core 1 through the first insulator 2. A ring body 4 around which the wire 3 is wound, a ring-shaped insulating case 10 that covers the entire surface of the ring body 4 to construct high-voltage insulation, an electrostatic shielding structure 20 formed on the outer surface of the insulating case 10, A secondary winding 30 wound around the outer surface of the insulating case 10 via the electric shielding structure 20 is provided. A hollow lead lead-out portion 13 for leading out the primary lead wires 3a and 3b of the primary winding 3 to the outside of the case is integrally formed in a part of the insulating case 10. Further, a minute gap G is formed between the inner surface of the insulating case 10 and the ring body 4, and the heat radiating port 15 and the outside air intake port 17 are partially formed in the insulating case 10 in communication with the gap G.

  As shown in FIG. 5, the wound core 1 is obtained by winding a long band-shaped directional silicon steel sheet 1 a in multiple layers, and increasing the magnetic flux density to reduce the core cross-sectional area. A first insulator 2 made of an insulating coating film is applied to the entire surface of both ends in the axial direction and the inner and outer peripheral surfaces of the wound core 1. The first insulator 2 may be a resin layer formed by immersing the wound iron core 1 in a molten resin, or an insulating tape (not shown) wound around the wound iron core 1. The wound core 1 whose entire surface is covered with the first insulator 2 is used without being grounded. A primary winding 3 is wound around the wound iron core 1 via a first insulator 2 to form a ring body 4 as shown in FIG. The first insulator 2 may be of a low voltage insulation of about 1500 V because the wound core 1 is used without being grounded. Lead wires 3 a and 3 b at the beginning and end of winding of the wound core 1 are drawn out to one end face side of both axial end faces of the wound core 1. Such a ring body 4 is reduced in size and weight for the following reason.

  One means for reducing the size and weight of the transformer itself is how to reduce the amount of iron cores and windings used. As means for reducing the iron core, the cross-sectional area is reduced as the wound core 1 of the grain-oriented silicon steel sheet, and the iron loss is reduced. As a means for reducing the number of windings, the temperature rise is kept low, the current density of the windings is increased, and as a result, the primary winding 3 is thinned to reduce the amount of use even with the same number of turns. To do. By reducing the cross-sectional area of the wound core 1, the length of the winding wound around the wound core 1 can be shortened, and the entire winding length can be shortened. The temperature can be suppressed to a small level, and the temperature rise can be suppressed. Further, the wound core 1 with less iron loss has a small temperature rise in the iron core itself, and is less affected by the temperature rise on the primary winding 3. Further, since the wound core 1 is not grounded, the first insulator 2 may be low-voltage insulated so that the primary winding 3 is not damaged at the corners of the wound core 1. Therefore, the primary winding 3 is wound directly and tightly around the wound iron core 1 to suppress the substantial outer dimension of the ring body 4. Further, since the ring-shaped wound core 1 can be uniformly wound over the entire magnetic path length, the winding layer is minimized and the outer dimension of the ring body 4 is minimized. Further, since the average winding length per turn of the primary winding 3 is short and the winding resistance is small, the ring body 4 can be manufactured with a small temperature rise and can be made sufficiently small. Since the ring body 4 is covered with the insulating case 10, the temperature is likely to rise. However, by providing the insulating case 10 with a heat dissipation function as described later, the temperature rise is sufficiently suppressed and sufficient. Small and lightweight. As the ring body 4 is reduced in size and weight, the insulating case 10 is reduced in size, and the electrostatic capacity can be easily reduced by the electrostatic shielding structure 20 formed on the outer surface thereof, and the performance of the transformer itself is improved.

  FIG. 4 shows a specific example of the insulating case 10. The insulating case 10 includes a first case 11 and a second case 12 that are resin molded products. When the ring body 4 is divided into an upper and lower lower ring region 4a and an upper ring region 4b, the first case 11 is fitted in the lower ring region 4a so as to be detachable from below, and is attached to the upper ring region 4b. The second case 12 is fitted so as to be detachable from above. The first case 11 integrally includes a ring-shaped bottom plate portion 11a, an inner cylinder portion 11b rising from the inner periphery of the bottom plate portion 11a, and an outer cylinder portion 11c rising from the outer periphery of the bottom plate portion 11a. The lower ring region 4a of the ring body 4 is fitted into the upper opening ring-shaped groove portion surrounded by the bottom plate portion 11a, the inner tube portion 11b, and the outer tube portion 11c. The second case 12 integrally includes a ring-shaped top plate portion 12a, an inner tube portion 12b that falls from the inner periphery of the top plate portion 12a, and an outer tube portion 12c that falls from the outer periphery of the top plate portion 12a. The upper ring region 4a of the ring body 4 is fitted into a ring-shaped groove portion at the lower end opening surrounded by the top plate portion 12a, the inner cylinder portion 12b, and the outer cylinder portion 12c. The open ends of the inner cylindrical portions 11b and 12b of both cases 11 and 12 fitted to the inner periphery of the ring body 4 are thinned so as to overlap each other. Similarly, the open end portions of the outer cylindrical portions 11c and 12c of both the cases 11 and 12 are also thinned so as to overlap each other.

  As shown in FIG. 6, the electrostatic shield 20 formed on the outer surface of the insulating case 10 includes a first electrostatic shield 21 formed almost entirely on the outer surface of the first case 11 and the second case 12. The second electrostatic shield 22 formed almost entirely on the outer surface is divided into two. The inner peripheral upper edge portion 11'b of the inner cylindrical portion 11b and the outer peripheral upper edge portion 11'c of the outer cylindrical portion 11c, which are open ends of the first case 11, are creeping insulation portions without an electrostatic shield. The inner peripheral lower edge portion 12'b of the inner cylindrical portion 12b and the outer peripheral lower edge portion 12'c of the outer cylindrical portion 12c, which are open ends of the second case 12, are creeping insulation portions without an electrostatic shield. When the thinned opening ends of the first case 11 and the second case 12 are overlapped with each other inside and outside, the open ends of the electrostatic shields 21 and 22 of both cases face each other at this overlapped portion, Electrostatic shielding is performed at the polymerized portion. In addition, creeping insulation portions such as the inner peripheral upper edge portion 11′b of the overlapped portion separate the first electrostatic shield 21 and the second electrostatic shield 22, and the first electrostatic shield 21 and the second static shield 21 are separated. A short-circuit current flow (one turn short-circuit) due to the induced voltage between the electric shields 22 is blocked.

  The lead lead-out portion 13 and the heat radiation port 15 are formed in the second case 12 of the insulating case 10 described above, and the outside air intake port 17 is formed in the first case 11. The lead lead-out part 13 is a cylindrical inner lead-out part 13a formed integrally with the top plate part 12a of the second case 12, and a cylindrical shape extending radially outward from the outer peripheral upper part of the outer cylinder part 12c. The outer derivation | leading-out part 13b is provided. A heat radiation port 15 is formed in a heat radiation tube 16 that is integrally extended radially outward from a part of the outer periphery of the outer tube portion 12 b of the second case 12. The heat radiating cylinder 16 is a rectangular tube having a vertically long rectangular cross section, and is formed at a fixed position directly below the outer lead-out portion 12 b of the lead lead-out portion 13. An outside air intake port 17 is formed in an outside air intake cylinder 18 that is integrally extended radially outward from a part of the outer periphery of the outer cylinder portion 11 b of the first case 11. The outside air intake cylinder 18 is a rectangular tube with a vertically long cross-sectional rectangle. The outside air intake cylinder 18 may be a round cylinder. Both the heat radiation port 15 and the outside air intake port 17 communicate with a gap G formed between the ring body 4 and the insulating case 10.

  As shown in FIG. 4, when the ring case 4 is covered with the first case 11 and the second case 12, the pair of lead wires 3 a and 3 b on the ring body 4 are inserted into the lead lead-out portion 13 of the second case 12. Derived outside the case. The outside air intake cylinder 18 of the first case 11 is positioned directly below the heat radiating cylinder 16 of the second case 12. The secondary winding 30 is wound in one layer except for the region where the lead lead-out portion 13, the heat radiating cylinder 16, and the outside air intake cylinder 18 are arranged vertically on the entire surface of the ring-shaped insulating case 10 including the first case 11 and the second case 12. By winding, a lightning strengthening type low voltage insulation transformer as shown in FIG. 2 is manufactured. By arranging the lead lead-out portion 13, the heat radiating cylinder 16, and the outside air intake cylinder 18 in a line in the axial direction on the outer periphery of the insulating case 10, it is easy to wind the secondary winding 30 while avoiding this line of protrusions. . Further, by forming the lead lead-out portion 13, the heat radiating cylinder 16, and the outside air intake cylinder 18 in the empty space between the winding start and the winding end of the secondary winding 30, it is possible to effectively use the empty space. It is possible to secure an insulation distance from the secondary winding 30 in space.

  As shown in FIG. 1, when using a lightning proof type low-voltage insulation transformer with the lead lead-out portion 13 facing upward, when the primary winding 3 generates heat by energization, the hot air rises through the gap G and enters the heat radiating tube 16. Enters and is discharged from the heat radiation port 15. At this time, outside air (cold air) is actively taken into the gap G from the outside air intake port 17 of the outside air intake cylinder 18, heat dissipation is promoted, and temperature rise of the primary winding 3 is suppressed. By increasing the length of the heat radiating cylinder 16 and the outside air intake cylinder 18, a tunnel effect is obtained and heat dissipation is increased. In addition, by making the outer lead-out portion 13b of the lead lead-out portion 13 long, an insulation distance between the primary lead wires 3a and 3b and the secondary winding 30 is ensured, and high-voltage insulation between the windings is stably performed.

  Moreover, the axial height of the insulating case 10 can be set to a minimum by extending the outer lead-out portion 13b, the heat radiating cylinder 16, and the outside air intake cylinder 18 from the outer periphery of the ring-shaped insulating case 10 in the radially outward direction. Thus, the lightning-proof low-voltage insulation transformer can be made thinner. Such a thin transformer is suitable for a wall-mounted or pillar-type lightning resistant transformer. This also applies to the other embodiments shown in FIGS.

  7 and FIG. 8, the lightning strengthening type low voltage insulation transformer of the embodiment is configured such that the primary lead wires 3a and 3b led out from the tip of the outer lead-out portion 13b of the lead lead-out portion 13 are connected to the flexible insulating cylinder 19. It is covered with. The insulating cylinder 19 is a cylinder having a large opening cross-sectional area into which the two primary lead wires 3a and 3b are inserted with a margin. In FIG. It is crimping | bonding to the outer periphery of 13b. The insulating cylinder 19 has a length that extends to the vicinity of the terminal conductor portions 3c and 3d formed at the tips of the primary lead wires 3a and 3b, and forms a heat radiation gap G 'with the primary lead wires 3a and 3b. . The heat radiating gap G ′ is opened at the tip of the insulating cylinder 19, and the heat in the insulating case 10 is released like the heat radiating port 15. With this heat dissipation, the temperature rise of the primary winding 3 is further suppressed.

  In addition, since the rubber insulating cylinder 19 has flexibility to bend together with the primary lead wires 3a and 3b, it is possible to facilitate the connection of the primary lead wires 3a and 3b to other devices. Further, since the insulating cylinder 19 covers the terminal conductor portions 3c and 3d at the tips of the primary lead wires 3a and 3b to secure an insulation distance from the secondary winding 30, the outer lead-out portion 13b of the lead lead-out portion 13 is secured. The substantial protrusion length L can be made sufficiently shorter than in the case of FIG.

  Next, the embodiment shown in FIGS. 9 and 10 will be described. The lead lead-out portion 13 in this embodiment corresponds to a combination of the lead lead-out portion 13 and the heat radiating cylinder 16 in FIG. The lead lead-out portion 13 shown in FIG. 9 has an inner lead-out portion 13a and an outer lead-out portion 13b. The outer lead-out portion 13b is formed in a vertically long rectangular tube as shown in FIG. An insertion port 15 ′ through which the wires 3 a and 3 b are inserted is used, and a lower part of the internal space is a heat radiation port 15. The outer lead-out portion 13b is a lead lead-out and heat radiating tube portion. By using this lead lead-out and heat radiating tube portion, the substantial opening cross-sectional area of the heat radiating port 15 is increased by the amount of the insertion port 15 ', and the heat radiation performance is increased.

  Further, the insulating case 10 having the lead lead-out portion 13 in FIG. 9 having a structure in which the lead lead-out portion 13 and the heat radiation cylinder 16 in FIG. 1 are combined is simpler than the insulating case 10 in FIG. 1 and FIG. Easy to manufacture. Furthermore, by making the outer lead-out portion 13b of the lead lead-out portion 13 of FIG. 9 long as the heat radiating tube 16, the insulation distance between the primary lead wires 3a and 3b and the secondary winding 30 is ensured similarly to the case of FIG. High voltage insulation between windings is performed stably.

  In the embodiment shown in FIG. 11, a pair of lead lead-out portions 13 ′ and 13 ′ into which two primary lead wires 3 a and 3 b are inserted one by one in the insulating case 10 are provided, and the top plate portion of the second case 12 is provided. A cylindrical heat radiating cylinder 16 ′ is projected from 12 a. The hollow of the heat radiating cylinder 16 ′ is a heat radiating port 15. By forming a single heat radiating tube 16 ′ between the pair of lead lead-out portions 13 ′ and 13 ′ on the top plate portion 12 a, the heat dissipation in the insulating case 10 is improved.

  In addition, the lightning strengthening type low voltage insulation transformer of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

It is sectional drawing of the lightning-proof reinforced type low voltage | pressure insulation transformer which shows embodiment of this invention. It is a perspective view of the insulation transformer of FIG. It is a partial side view of the insulation transformer of FIG. It is a disassembled perspective view of the ring body and insulation case in the middle of manufacture of the insulation transformer of FIG. It is a perspective view before winding the primary winding of the ring body of FIG. It is the elements on larger scale of the 1st case and the 2nd case which comprise the insulation case of FIG. It is a fragmentary sectional view of the lightning proof strengthening type low voltage insulation transformer which shows other embodiments. It is a partial side view of the insulation transformer of FIG. It is a fragmentary sectional view of the lightning strengthening type low voltage insulation transformer which shows other embodiments. FIG. 10 is a partial side view of the insulation transformer of FIG. 9. It is a perspective view of the lightning proof strengthening type low voltage insulation transformer which shows other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Iron core 2 1st insulator 3 Primary winding 3a, 3b Primary lead wire 4 Ring body 10 Ring-shaped insulation case 11 First case 12 Second case 13 Lead lead-out part 13 'Lead lead-out part 13a Inner lead-out part 13b Outer lead-out Part 15 Radiation port 16 Radiation tube 16 'Radiation tube 17 Outside air intake 18 Outside air intake tube 19 Flexible insulating cylinder 20 Electrostatic shield 21 First electrostatic shield 22 Second electrostatic shield 30 Secondary winding G gap G 'Heat radiation gap

Claims (9)

A ring body in which a primary winding is wound on a ring-shaped wound iron core via a first insulator attached to the entire surface of the wound core, and a high-voltage insulation covering the entire surface of the ring body. A ring-shaped insulation case having a lead lead-out portion for leading the primary lead wire of the primary winding to the outside and a secondary winding wound around the insulation case; A heat dissipation structure for an insulation transformer,
A lightning strengthening type low-voltage insulation transformer characterized in that the insulation case is provided with a heat radiation port that communicates with a gap between the insulation case and the ring body and discharges heat generated by the ring body to the outside of the case. Heat dissipation structure.   The heat radiation structure of a lightning proof strengthening type low voltage insulation transformer according to claim 1, wherein the heat radiation port is a heat radiation cylinder protruding in a radial direction from an outer periphery of the ring-shaped insulation case.   2. The heat dissipation structure of a lightning proof strengthening type low-voltage insulation transformer according to claim 1, wherein the heat radiation port is a heat radiation cylinder protruding in an axial direction from one end surface of both end surfaces in the axial direction of the ring-shaped insulating case. .   The primary lead wire led out from the tip of the lead lead-out portion of the insulating case is covered with a flexible insulating cylinder, and a heat radiation gap communicating with the heat radiation port is formed between the insulating cylinder and the primary lead wire. The heat dissipation structure for a lightning proof strengthening type low voltage insulation transformer according to any one of claims 1 to 3.   The lead lead-out portion of the insulating case has a lead lead-out / radiation tube portion that has both the insertion port for the primary lead wire and the heat radiation port. Heat dissipation structure for lightning strengthened low-voltage insulation transformer.   6. The heat dissipation structure for a lightning proof strengthening type low voltage insulation transformer according to claim 5, wherein the lead lead-out and heat radiating cylinder portion extends in a radial direction from an outer periphery of the ring-shaped insulating case.   The lightning strengthening type low voltage insulation transformer according to any one of claims 1 to 6, wherein an outside air intake port communicating with the heat radiation port is formed in a portion of the insulation case away from the heat radiation port. Heat dissipation structure.   8. The heat dissipation structure for a lightning proof strengthening type low voltage insulation transformer according to claim 7, wherein the outside air intake port is an outside air intake tube protruding radially from the outer periphery of the ring-shaped insulating case.   9. The heat dissipation structure for a lightning proof strengthening type low-voltage insulation transformer according to claim 8, wherein the outside air intake cylinder, the lead lead-out portion, and the radiation cylinder are arranged in a line in the axial direction on the outer periphery of the ring-shaped insulation case. .

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