Adjustable contact jaw spacing for circuit breaker plug-in base

The present invention relates to adapting a circuit breaker plug-in base to various circuit breaker frame sizes and more particularly to adjusting the spacing of contact jaws of a circuit breaker plug-in base.

Conventionally, a plug-in base for a circuit breaker is mounted on a panel board or other base structure and is wired to circuitry on the base structure. A circuit breaker unit is installed in the plug-in base by inserting stabs protruding from the circuit breaker unit into jaws fixed to the plug-in base. The jaw/stab connection provides the primary electrical connection between the circuit breaker unit and the plug-in base. This connection may also mechanically retain the circuit breaker in the plug-in base.

Conventionally, a plug-in base is configured for a specific circuit breaker frame size. Thus, there is a need to be able to adapt a plug-in base so as to be used with different circuit breaker frame sizes.

An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by a method of adjusting spacing between first and second jaw structures of a plug-in base for receiving a circuit breaker. The method includes providing a plug-in base having first and second jaw structures constructed and arranged to receive stabs of a circuit breaker. The first jaw structure is disposed in a first housing and the second jaw structure is disposed in a second housing. Each of the first and second housings has an upper surface and an opposing lower surface. A first spacer is placed between the first jaw structure and the upper or lower surface of the first housing and a second spacer is placed between the second jaw structure and the upper or lower surface of the second housing to define a certain spacing between the first and second jaw structures. The spacers are movable to different positions to change the spacing between the jaw structures.

In accordance with another aspect of the invention, a plug-in base for a receiving a circuit breaker is provided. The plug-in base includes a main body portion having first and second jaw structures constructed and arranged to receive stabs of a circuit breaker. The first jaw structure is disposed in a first housing and the second jaw structure is disposed in a second housing. Each of the first and second housings has an upper surface and an opposing lower surface. A first spacer is disposed between the first jaw structure and the upper or lower surface of the first housing. A second spacer is disposed between the second jaw structure and the upper or lower surface of the second housing. The spacers define a certain spacing between the first and second jaw structures.

Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.

Preferred embodiments of the invention are described in greater detail herein below with reference to the drawings wherein:

FIG. 1 is a side view, partially in section of a plug-in base for a circuit breaker, having spacers to space the jaw structure in a first position in accordance with the principles of the present invention;

FIG. 2 is a side view, partially in section of a plug-in base for a circuit breaker, having spacers to space the jaw structure in a second position in accordance with the principles of the present invention;

FIG. 3 is a side view, partially in section of a plug-in base similar to FIG. 2 but having a rear connecting style bus;

FIG. 4 is a side view, partially in section of a plug-in base similar to FIG. 3 but having a rear connecting style bus;

FIG. 5 is a plan view of a bus of the plug-in base of FIG. 1;

FIG. 6 is a side view of the bus of FIG. 5; and

FIG. 7 is a perspective view of a jaw structure of FIG. 1 - 4 .

With reference to FIG. 1, a circuit breaker plug-in base, generally indicated at 10 , is provided in accordance with the principles of the present invention. The plug-in base 10 is constructed and arranged for mounting at least two different frame size circuit breakers (not shown) thereto. The plug-in base 10 includes a main body portion 12 defining first and second jaw structures 14 and 16 , respectively. Each jaw structure 14 and 16 has a common height A, and pairs of three fingers 15 (FIG. 7) to receive stabs of a circuit breaker in the conventional manner to electrically connect the circuit breaker to the plug-in base 10 . The circuit breaker and stabs or studs may be of the type disclosed in U.S. Pat. No. 5,837,949, the content of which is hereby incorporated into the present specification by reference.

The first jaw structure 14 is disposed in a first housing 18 and the second jaw structure is disposed in a second housing 20 . Each of the first and second housings 18 and 20 has an upper surface 22 and an opposing lower surface 24 . To define the spacing between the jaw structures 14 and 16 to align with stabs of a first frame size circuit breaker, a first spacer 26 is placed between the first jaw structure 14 and the upper surface 22 of the first housing 18 with the first jaw structure 14 contacting the lower surface 24 of the first housing. In addition, a second spacer 28 is placed between the second jaw structure 16 and the lower surface 24 of the second housing 20 with the second jaw structure 16 contacting the upper surface 22 of the second housing 20 . A mounting fastener 30 couples a bus 32 to the associated jaw structure 14 and 16 via bore 31 therein (FIG. 7) to complete the assembly. Thus, the spacers 26 and 28 define a first spacing between the jaw structures 14 and 16 to align with, for example, stabs of a 125 Amp circuit breaker frame. The spacers 26 and 28 are comprised of electrically insulating material such as a thermosetting plastic.

To adjust the jaw structure spacing to align with, for example, stabs of a 160 Amp or 250 Amp circuit breaker frame, the mounting fastener 30 which couples a bus 32 to an associated jaw structure 14 and 16 is removed from each jaw structure. In the embodiment of FIG. 1, the bus is of the front connecting type. Each bus 32 is then slid-out from the associated receiving slot 34 in the plug-in base 10 to gain access to the rear of the associated housing 18 or 20 . The spacers 26 and 28 are removed from the associated housing. The first jaw structure 14 is positioned against the upper surface 22 of the first housing 18 while the spacer 26 is positioned against the lower surface 24 of the first housing 18 (FIG. 2 ). In addition and as shown in FIG. 2, the second jaw structure 16 is positioned against the lower surface 24 of the second housing 20 while the spacer 28 is positioned against the upper surface 22 of the second housing 20 . Thus, a second position of the jaw structures is provided.

Each connecting bus 32 has a slotted hole 36 which provides multiple connecting positions with respect to the associated jaw structure. With reference to FIGS. 1, 2 , 5 and 6 , each bus 32 includes a protrusion 38 which engages surface 39 of the plug-in base 10 to ensure the proper location of the bus 32 for alignment with mounting holes 40 in the jaw structures 14 and 16 . Thus, bus 32 is simply slid into a receiving slot 34 as far as it will go and the slotted hole 36 will be aligned with the mounting hole in the associated jaw structure. The protrusions are preferably formed by stamping.

FIGS. 3 and 4 show a second embodiment of a plug-in unit 10 ′ which is identical to that of FIGS. 1 and 2, except for a rear connecting style bus 32 ′. FIG. 3 shows the jaw structures 14 and 16 spaced by spacers 26 and 28 in position to receive a 160 Amp or 250 Amp frame circuit breaker frame, and FIG. 4 shows the spacers in position to receive a 125 Amp circuit breaker frame. The shape of the bus 32 ′ defines a stop surface 42 that engages an inner surface 44 of the plug in base 10 ′ to properly align the bus 32 ′ for mounting with respect to the associated jaw structure 14 or 16 .

The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.