Current transformer mounting mechanism for circuit breaker

Abstract: Current transformer mounting mechanism which mounts a current transformer having a core on a circuit breaker to diminish impact caused by switching operation comprising: at least one substantially U-shaped fitting board having curved portions at both ends thereof; at least one setscrew for mounting said fitting board to the core of the current transformer; and a current transformer mounting portion having opposing walls, each wall being provided with a shoulder where the fitting board being fixed; the current transformer being mounted to the current transformer mounting portion by inserting the fitting board to the current transformer mounting portion. The fitting board is preferably provided with embossed tabs at curved portions thereof.

Description: The present invention relates to a current transformer mounting mechanism according to the preamble of claim 1. Figures 4 and 5 show a current transformer mounting mechanism conventionally used for a circuit breaker This circuit breaker corresponds to the circuit breaker which is sold under the trademark "Super Scrum" by the Firm Mitsubishi, Japan. In the figures, denoted 1 is a circuit breaker body and 1a is a current transformer mounting portion, 2 a main circuit conductor, 3 a current transformer cover, and 4 a current transformer. The current transformer 4 comprises winding portions 4a, a core 4b, and core setscrews 4c. Next, a mounting method will be described. The current transformer is mounted by fixing the core 4b with a shoulder 1a of the current transformer mounting portion at four points arranged up and down, and from side to side. With the conventional circuit breaker thus far described, since the current transformer is mounted by the above method, impact caused by switching operation is directly transmitted to the current transformer 4, leading to a possibility of deterioration of parts constituting the current transformer. Further, since the core 4b is formed by accumulated thin sheets, there is a problem that insertion of the core 4b becomes difficult due to slips in the thin sheets in assembly. It is therefore the object of the present invention to provide a current transformer mounting mechanism for circuit breaker which diminishes the impact caused by the switching operation, makes it easy to insert the current transformer to the mounting portion, and accurately fixes the current transformer. This object is solved by the measures indicated in claim 1. In the present invention, a fitting board contacts with a current transformer fitting portion to diminish impact caused by switching operation and the fitting board makes it possible to mount and dismount a current transformer with ease. The above features and advantages of the invention and manner of realizing them will become more apparent from a study of the following description with reference to the attached drawing showing a preferred embodiment of the invention. In the drawings : Figure 1 is a front elevation of a principal part of the circuit breaker according to one embodiment of the present invention; Figure. 2 shows a cross-sectional view taken along the line II-II of Fig. 1; Figure 3 illustrates a perspective view of the current transformer described in Fig. 2; Figure 4 shows a front elevation of a principal part of a conventional circuit breaker; and Figure 5 is a cross-sectional view taken along the line V-V of Fig. 4. One embodiment of the present invention will be described with reference to Figs. 1 to 3. Figure 1 is a front elevation of a principal part of the circuit breaker according to the embodiment of the present invention. Figure. 2 shows a cross sectional view taken along the line II-II of Fig. 1. Figure 3 illustrates a perspective view of the current transformer shown in Fig. 2. The component parts identical with or equivalent to the conventional transformer are designated by the same symbols. In the figures, denoted 5 is a U-shaped fitting board having curved portions 5a and being symmetrically mounted to a core 4b with setscrews 4c. Reference numeral 6 shows embossed tabs provided to the curved portions 5a of the fitting board 5. Denoted 4d is an outgoing portion of the current transformer 4. In the current transformer as described above, impact in switching operation is not directly transmitted to the core 4b and the winding portions 4a, and force transmitted from the embossed tabs 6 is diminished by resilience of the curved portion 5a. Meanwhile, the design in which the distance between the embossed tabs is slightly longer than the diameter of the mounting portion 1a is able to diminish looseness of the current transformer. Further, by virtue of the existence of rounded portions at the curved portions of the fitting board 5, there is another advantage that mounting or dismounting of the current transformer becomes easier without being caught by the current transformer mounting portion in assembly. While in the aforementioned embodiment, the case where the present invention is applied to a circuit breakers has been described, it is to be noted that the present invention may be applied to other parts of circuit breakers or equipment other than circuit breakers and similar effect will be obtained. As described above, the present invention provides a current transformer mounting mechanism for a circuit breaker in which impact in switching operation is less apt to be transmitted and a current transformer is inserted to and accurately mounted to its mounting portion with ease.

Claims: Current transformer mounting mechanism, wherein a current transformer (4) having a core (4b) is mounted on shoulders (1b) which are provided on opposing walls of a current transformer mounting portion (1a), characterized in that at least one substantially U-shaped fitting board (5) having curved portions (5a) at both ends thereof and at least one setscrew (4c) for mounting said fitting board (5) to said core (4b) of said current transformer (4) are provided, and in that said current transformer (4) is mounted to said current transformer mounting portion (1a) by inserting said fitting board (5) between said shoulders (1b) of said opposing walls of said current transformer mounting portion (1a). Current transformer mounting mechanism according to claim 1, characterized in that said fitting board (5) is provided with embossed tabs (6) at curved portions (5a) thereof.

Inventors: HIROTSUNE KOJI C O MITSUBISHI, HIROTSUNE, KOJI, C/O MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1991
Main classification: H01H83
IPC codes: H01F27, H01H71, H01H83