Multi-pole molded case circuit breaker with a common contact operating crossbar member

A multipole molded case circuit breaker has a single handle assembly contained in a first pole along with a movable contact arm assembly. A second pole has a movable contact arm assembly connected to the first contact arm assembly by a crossbar member so that the arms move in unison during normal operation. Each pole contains a tripping mechanism for tripping the breaker pole. The breaker mechanisms are connected for uniform tripping of all poles.

CROSS REFERENCE TO RELATED APPLICATIONS 
The subject matter described in this application is related to the material 
disclosed in co-filed patent applications SN 656,236 "A Molded Case 
Circuit Breaker Having A Reinforced Housing"--B. DiMarco and C. W. 
Stanford; SN 656,150 "Circuit Breaker Contact Arm Assembly Having A 
Magnetic Carrier"--B. DiMarco and C. W. Stanford, and SX1 656,230 
"Magnetic Structure For Calibrating A Circuit Breaker"--W. Young. 
BACKGROUND OF THE INVENTION 
This invention relates to molded case circuit breakers and more 
particularly to a circuit breaker which has a common crossbar member for 
operation of all poles of a multi-pole circuit breaker simultaneously. 
A circuit breaker normally serves the dual function of opening and closing 
a circuit. Where the circuit breaker consists of two or more poles, it is 
desirable to open or close all poles of the breaker at the same time under 
normal tripping conditions or normal overcurrent conditions. To accomplish 
this, there have been arrangements wherein the operating handles for each 
pole have been mechanically tied together externally so that operation of 
one handle would operate all handles. More modern circuit breakers are 
single-handle devices, that is, for a multi-pole arrangement there is but 
one operating handle. In this arrangement, the tripping mechanisms are 
internally mechanically linked by a common shaft so that operation of the 
handle opens or closes all poles. It can be understood, that these 
arrangements require more parts and are thus most costly than more simple 
arrangements. However, it is desirable to gang operate the poles of a 
multi-pole circuit breaker. 
U.S. Pat. No. 4,409,573 which issued on Oct. 11, 1983 to Bernard DiMarco 
and Andrew J. Kralik disclose a circuit breaker which has a contact arm 
which is pivotable about a cross bar. In the three-pole version, the other 
two poles of the circuit breaker are also connected to the crossbar to 
facilitate opening and closing of all three poles of the circuit breaker 
in unison under normal operating conditions. However, the tripping 
mechanisms are connected by a shaft extending through all three poles. 
Accordingly, it can be appreciated that it would be highly desirable to 
provide a simple mechanism for operating the contact arms of all poles of 
a multi-pole circuit breaker in unison under normal conditions which is 
simple and can be changed in the field. 
Because many circuit breakers are used in control panels and other 
apparatus where space is limited and at a premium, there is a tendency to 
minimize the size of circuit breakers where possible. Thus, it can be 
appreciated that it would be highly desirable to provide a compact circuit 
breaker arrangement for a multi-pole circuit breaker in which the contacts 
of the poles operate in unison during normal conditions. 
Accordingly, it is an object of this invention to provide a compact 
multi-pole circuit breaker arrangement. 
Another object of this invention is to provide a circuit breaker 
arrangement which has the contact arms operating in unison during normal 
conditions. 
Another object of this invention is to provide a compact circuit breaker 
arrangement which is simple to assemble. 
SUMMARY OF THE INVENTION 
Briefly stated, in accordance with one aspect of the invention, the 
foregoing objects are achieved by providing a multi-pole molded case 
circuit breaker in which the tripping mechanisms for the poles are 
connected by a tongue and groove arrangement and the contact arms for the 
poles are tied together with a cross bar for operation in unison between 
the open and closed positions. By tieing the contact arm assemblies of the 
poles together, the operating handle mechanism of only one pole is 
required for the multi-pole configuration. This yields a compact 
arrangement which uses a minimum of components. By connecting the tripping 
mechanisms with a tongue and groove connection, it is simple to assemble 
the circuit breaker and to add poles.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring first to FIG. 4, there is shown a multi-pole circuit breaker 10 
which has two poles. It has a center or first pole 12 and a left or second 
pole 14. Each pole is packaged in its own molded housing. The two houses 
are connected together to form a single molded case circuit breaker 10. 
While the embodiment of FIG. 4 basically shows a two-pole arrangement, a 
three-pole arrangement can also be used. To form a three-pole arrangement, 
a right pole is added to the two poles shown in FIG. 4. The left pole and 
the right pole are similar. 
Referring to FIGS. 1 and 2, the center pole is equipped with an operating 
handle assembly 16 which has an operating handle 18 which is operable 
between an ON position and an OFF position. The operating handle assembly 
16 is unique to the center pole. Where left and right poles are used, 
these poles do not have an operating handle assembly as does the center 
pole. Thus, the multi-pole circuit breaker has but one operating handle 
assembly. 
The center pole also contains a contact arm assembly 20 which has blow open 
contacts which are movable between a closed position and an open position. 
A linkage assembly 22 connects the handle assembly 16 and the contact arm 
assembly 20 so that the contacts may be opened and closed by moving the 
operating handle 18 between the closed and opened positions. 
The center pole 12 contains a tripping mechanism 23C which is mounted in 
the housing and operable to trip the breaker 10. Movement of the handle 18 
from the OFF position to the ON position closes the contacts and stores 
energy mechanically for tripping the breaker. In response to rotation of 
the tripping mechanism 23, the tripping energy is released opening the 
contacts. As mentioned, only the center pole contains the operating handle 
assembly 16 which stores the tripping energy. Where a left pole 14 is 
used, its tripping mechanism 23L engages the tripping mechanism 23C of the 
center pole 23 so that either pole can release the tripping energy. The 
tripping mechanisms 23L and 23C may interconnect by means of a tongue and 
groove connection or other convenient manner, such as a splined 
connection, for example. In this manner, operation of one tripping 
mechanism for any reason automatically and simultaneously operates the 
other tripping mechanisms thereby releasing the tripping energy. 
The contact arm assembly 20 is equipped with a bracket 24 through which 
extends a crossbar member 26. The crossbar member is constructed of a very 
strong insulative material, such as glass epoxy, for example. The crossbar 
26 may be a single piece or may consist of one piece per pole wherein the 
pieces are joined using a splined joint or other simple, secure joint. It 
has been found economically advantageous to form the crossbar 26 in a 
single piece. The crossbar fits in the bracket and is preferably secured 
therein by deforming the bracket about the crossbar. This may take the 
form of dimples or other indentations or a screw or fastener may be used. 
It has been found simple and efficient to use a slight indentation or 
dimple to secure the crossbar member to the bracket. By this construction, 
the crossbar member moves with the contact arm assembly. The crossbar 
member 26 moves with the bracket whether the contacts open because of 
severe over current or fault conditions or whether the motion is due to 
operation of handle 18 or the normal over current circuit interrupting 
function of the circuit breaker. 
Referring to FIG. 3, the second or left pole 14 is similar to the main pole 
12 except that the left pole does not have an operating handle assembly. 
The left pole does contain a contact arm assembly 28 which has a bracket 
30 attached thereto. The bracket 30 simply slides onto the crossbar 26 so 
that adding a pole is a simple matter. The left pole 14 also contains a 
means 32 for adjusting the opening current and a means 34 for manually 
tripping the pole. The first and second poles also have tripping 
mechanisms 23C, 23L which interconnect so that when one pole trips, the 
other pole trips also. 
Referring to FIGS. 1-4, the crossbar member 26 extends from the first pole 
12 to the second pole 14. The crossbar member 26 extends from the bracket 
24 of the main pole through an opening in the housing of the main pole 12 
through an opening in the housing of the second pole 14 and into the 
bracket 30 of the contact arm assembly 28 of the second pole 14. By this 
construction, the operation of either contact arm is transmitted to the 
other contact arm assembly by the crossbar 26. This forces the contact arm 
assemblies to operate in unison. For example, pushing the trip button 34 
releases the contact arm assembly 28 so that the contacts open. Because 
the contact arm assembly 20 is joined with contact arm assembly 28 by the 
crossbar member 26, the contact arm assembly 20 also opens. Similarly, 
when one of the contact arm assemblies contacts are opened due to an 
overcurrent condition, the opening force is transmitted through the 
crossbar member to the other contact arm assembly thereby opening its 
contacts simultaneously. Similarly, operation of handle 18 will also cause 
both contact arm assemblies to open or close simultaneously because of 
their connection by the crossbar member 26. The contact arm assemblies, 
because they are tied by the crossbar member 26, must operate in unison. 
As will be evident from the foregoing description, certain aspects of the 
invention are not limited to the particular details of the examples 
illustrated, and it is therefore contemplated that other modifications or 
applications will occur to those skilled in the art. It is accordingly 
intended that the claims shall cover all such modifications and 
applications as do not depart from the true script and spirit of the 
invention.