JPH0422014B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a technique for preventing the formation of one electrical turn of a metallic coating provided on the surface of a coil of a surface-shielded resin molded transformer.

[Prior art]

In surface shield resin molded transformers,
The grounded metal coating provided on the surface of the coil has an insulating part that cuts off electrical connection in order to prevent voltage short circuits caused by electromagnetic induction from the primary winding of the transformer. It is necessary to prevent the formation of one turn. The voltage generated in this metal coating is equivalent to one turn of the winding, and is generally a low voltage. This can be achieved by blocking it.
However, sufficient consideration must be given to the possibility that a metallic conductor or the like accidentally comes into contact with the coil surface, or that metallic dust or the like adheres to the coil surface during long-term operation, causing a short circuit in the insulated portion. As a countermeasure for this, it becomes necessary to provide insulating parts at many places on the coil surface. However, in this structure, each gold metal coating partitioned by an insulating part must be grounded, which is cumbersome.

[Purpose of the invention]

The purpose of this project is to install the insulating part of the metal coating provided on the coil surface of a surface-shielded resin molded transformer in a safe and reliable location to interrupt electrical connection.

[Summary of the invention]

By covering the coil surface of a resin molded transformer with a metallic coating and grounding this coating, it is possible to maintain the potential of the coil surface at the ground potential. In the present invention, when the metallic coating is provided in an electrically continuous state over the entire surface of the coil, at least one insulating part is provided on the circuit formed of the metallic coating so as not to form one turn. The surface of the coil is located within the window of the iron core.

[Embodiments of the invention]

Figure 1 shows the main body of a three-phase inner iron type resin molded transformer. 1 is the iron core, 2, 3, and 4 are U, V, respectively.
This is a W-phase molded coil. 5 is an iron core fastener;
6 is a coil support inserted between the core fastener 5 and the end face of the coil. These transformer bodies are generally protected and used with a metal outer box or fence, but the oil-immersed transformer is completely housed in a metal outer case, making it impossible to touch the coils from the outside. In contrast, resin molded transformers have a structure that allows the coil surface to be easily touched.

Figure 2 shows the core of a three-phase internal iron transformer. The part indicated by 8 is the window of the iron core.

FIG. 3 shows an embodiment of the present invention of a three-phase transformer coil. An insulating part 9 is provided on the metallic coating applied over the entire surface of the coil except for the terminal part 10 so as to be outside the core window 8 when the coil and core are combined as shown in the figure. As a result, even if a conductor from the outside comes into contact with the coil surface, the insulating part 9 will not be short-circuited, so that the insulating part can be made highly safe against surface short-circuits.

[Effects of the Invention] The inside of the transformer core window 8 is a place where it is difficult for objects to enter. For example, a conductive object large enough to connect an insulating part that may short circuit the coil surface is generally difficult to enter unless it is intentionally pushed into the window 8. According to the present invention, a safe and highly reliable insulating part can be constructed by providing at least one insulating part of a metallic coating in the inside part of the transformer core window.

Although the above embodiment is applied to an inner iron type transformer, it can be similarly applied to an outer iron type transformer. In this case, the U and W phase coils can also be provided with insulating portions at two locations, similar to the V phase coil.

[Brief explanation of drawings]

Fig. 1a is a front view of a three-phase internal iron type resin molded transformer, Fig. 1b is a side view thereof, Fig. 2 is a perspective view showing the core structure of the three-phase internal iron type transformer, and Fig. 3 is a front view of a three-phase internal iron type resin molded transformer. The figure is a perspective view of an embodiment in which the present invention is applied to a surface-shielded coil of a three-phase inner iron type resin molded transformer. 1... Iron core, 2... U-phase coil, 3... V-phase coil, 4... W-phase coil, 8... Inside of iron core window, 9
...Insulating part facing inside the window core, 10...Terminal part.

Claims (1)

[Claims] 1. In a resin molded transformer where the coil surface is covered with a metallic coating and this metallic coating is grounded, the insulating part that interrupts the electrical connection of one turn along the coil surface of the metallic coating is faced into the window of the transformer core. A resin molded transformer with at least one location on the surface of the coil.