JPH0211781Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Technical field of invention] The present invention relates to an isolation transformer.

[Technical background of the invention and its problems]
For example, an isolation transformer is used to supply the electrical power. In such an isolation transformer, an electric field concentrates at the end of the secondary winding to which a high DC voltage is applied, which may cause dielectric breakdown.

Therefore, as shown in FIG. A curved portion 4a is formed in the annular solid insulator 4, and a layer 5 of conductive paint is formed on the outer peripheral surface of the annular solid insulator 4, and a layer 6 of conductive paint is formed on the inner peripheral surface of the annular solid insulator 4, thereby forming the secondary windings 3, 1.
Electric field concentration at the end of the secondary winding 2 is alleviated, and the secondary winding 3 is covered with a solid insulator 7 to prevent creeping flash between the two windings 2 and 3.

However, in the above-mentioned insulation transformer, in addition to the molding process of the annular solid insulator 4 between the primary winding 2 and the secondary winding 3, an annular solid insulator is also added to prevent creeping flash. Another solid insulator 7 must be molded to cover the material 4 and the secondary winding 3, and the insulation resistance against high DC voltages is still insufficient. Also, by molding the solid insulator 7, the weight of the high voltage device increases,
Material costs are extra.

Furthermore, since the size of the transformer container or the transformer body is limited, a sufficient distance must be maintained between the members made of angular metal material such as the channel 8 for holding down the core 1, as shown in FIG. Therefore, electric field concentration may occur, which may reduce the withstand voltage of the transformer.

[Purpose of the invention] The present invention was made based on the above circumstances, and it alleviates the electric field concentration at the winding ends, has insulation resistance against higher DC high voltages, and reduces the processing required. Iron core is less labor-intensive and inexpensive.
The aim is to obtain an insulating transformer that does not have a drop in withstand voltage due to electric field concentration between the channels that hold down the iron core.

[Summary of the invention] The isolation transformer of the invention includes a core, a primary winding and a secondary winding provided outside the core, and a primary winding and a secondary winding provided between the primary winding and the secondary winding. and a ring-shaped solid insulator having a conductive layer formed on its inner and outer peripheral surfaces, wherein both ends of the ring-shaped solid insulator project outward from each of the ends of the secondary winding, and the projecting portion has the A flange having a diameter larger than that of the secondary winding is provided, each end of the two conductive layers is located outside of each end of the primary winding and the secondary winding, and at least one of the two conductive layers one of the two ends is disposed in a circumferential groove having a semicircular arc cross section formed over the entire circumference on the inner periphery of the protrusion or on the surface of the flange facing the secondary winding;
A shielding plate convex upward is attached to the upper end of the flange on the side of the transformer body of the channel that presses and supports the core, and an insulating plate is attached to the shielding plate and the surface of the flange on the side of the transformer body. do.

[Embodiment of the invention] Fig. 3, in which the same parts as in Figs. 1 and 2 are denoted by the same reference numerals, shows a main part of an embodiment of the invention. In the present invention, an upwardly convex arc-shaped shielding plate 10 is attached to the upper end of the flange 8a of the channel 8 on the side closer to the transformer body 9, and the surfaces of the shielding plate 10 and the flange 8a on the transformer body 9 side are It is covered with an insulating plate 11 made of , rubber, plastic, or the like.

The shielding plate 10 alleviates the electric field concentration at the protrusion of the channel 8, and the insulating plate 11 stops the electrons that are still emitted even though the electric field concentration is alleviated by the shielding plate 10. Therefore, the insulation transformer is made small. However, there is no risk that the withstand voltage will decrease.

FIG. 4 is a sectional view showing a part of the isolation transformer of the present invention, and the same parts as in FIG. 1 are designated by the same symbols.
As shown in the figure, a primary winding 2 is placed on the outside of the core 1.
and a secondary winding 3 are provided, and an annular solid insulator 12 is provided between the primary winding 2 and the secondary winding 3.

The annular solid insulator 12 has protruding portions 12 a that protrude outward from both ends of the secondary winding 3 . A flange 13 having a flat portion perpendicular to the core axis on the side of the secondary winding 3 and having a diameter larger than the outer diameter of the secondary winding 3 is formed on the protruding portion 12a. Furthermore, a layer 5 of conductive paint is applied onto the outer peripheral surface of the annular solid insulator 12, and a layer 6 of conductive paint is applied onto the inner peripheral surface. Layers 5 and 6 of both conductive paints
The ends of each of the windings 2 and 3 are located outside of the ends of the windings 2 and 3. Both ends of each of the conductive paint layers 5 and 6 are arranged on grooves 14 and 15 each having a semicircular arc cross section formed on the inner periphery of the protruding portion 12a and the inner portion of the flange 13 over the entire periphery thereof. has been done. The ends of the conductive paint layer 5 thus face the ends of the opposing secondary windings 3 and the ends of the conductive paint layer 6 face the axis of the core 1.

Since the insulating transformer of the present invention is constructed as described above, the ends of both windings 2 and 3 are coated with conductive paint layers 5 and 6 applied on the inner and outer peripheral surfaces of the annular solid insulator 12. The electric field concentration at is alleviated. Moreover, each end of the conductive paint layers 5 and 6 has a semicircular arc shape in cross section, and one end of each of the conductive paint layers 5 and 6 is located at the end of the opposing secondary winding 3, and the other end is located at the axis of the core 1. As a result, the creepage distance between the primary winding 2 and the secondary winding 3 is substantially increased, and the risk of creepage flash is extremely small.

In addition, by increasing the thickness (axial dimension) of the flange 13 in FIG. 4, the risk of creeping flash is further reduced.

FIG. 5A shows the core and winding portion of a conventional isolation transformer, and FIGS. 5B to 5D show modified examples of the core and winding portion in the present invention. The creepage distance increases from B to D in FIG. 5, and the risk of creepage flash decreases in this order.

[Effects of the invention] As explained above, according to the invention, it is possible to obtain an insulating transformer that can withstand extremely high DC voltages, and since the insulator molding is only required once, the processing time is reduced. It is possible to obtain an isolation transformer that is small in size, lightweight, and inexpensive. Further, the withstand voltage is further increased by the shielding plate and the insulating plate attached to it.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a part of a conventional isolation transformer, Fig. 2 is a front view of a part of a conventional isolation transformer in cross-section, and Fig. 3 is a cross-section of a part of an embodiment of the present invention. 4 is a sectional view of the core and winding portion, FIG. 5A is a sectional view of the conventional core and winding portion, and FIGS. 5B to 5D are the cross-sectional views of the conventional core and winding portion. core,
It is a sectional view of a modification of a winding part. DESCRIPTION OF SYMBOLS 1... Core, 2... Primary winding, 3... Secondary winding, 5, 6... Layer of conductive paint, 12... Annular solid insulator, 8a... Protruding portion, 14, 15... groove.

Claims (1)

[Scope of utility model registration request] A core, a primary winding and a secondary winding provided on the outside of the core, and conductive layers provided between the primary winding and the secondary winding and formed on the inner and outer circumferential surfaces thereof, respectively. and an annular solid insulator, wherein both ends of the annular solid insulator protrude outward from each of both ends of the secondary winding, and this protrusion includes the two ends of the annular solid insulator.
A flange having a larger diameter than the secondary winding is provided, and each end of the two conductive layers is connected to the primary winding and the secondary winding.
located outside each end of the secondary winding, and both ends of at least one of the two conductive layers are formed on the inner periphery of the protrusion or on the surface of the flange facing the secondary winding over its entire periphery. A shielding plate convex upward is attached to the upper end of the flange on the side of the transformer body of the channel that presses and supports the core. An insulating transformer characterized by having an insulating plate attached to the main body side.