Traveling electrical connector

The electrical connector (24) of the present invention includes a coupling (26, 26') for attaching the connector (24) to an equipment cabinet (10) that will permit a certain amount of movement of the connector along the mating axis (64) after mating with a mating connector (32). The coupling (26, 26') includes U-shaped channels (68) attached to the cabinet that receive rollers (88) attached to the connector. The rollers have a V-shaped groove (98) that receives a circular portion (112) of a spring (108) for holding the connector (24) in position during mating but will expand allowing the mated connector pair (24, 32) to move along the mating axis (64) after mating.

The present invention relates to electrical connectors for electrically 
interconnecting removable components such as circuit breakers with other 
equipment in an equipment cabinet and more particularly to such connectors 
that are mated when the component is first inserted into the equipment 
cabinet a specific distance to an intermediate position and then the mated 
connectors are arranged to move along with the component as the component 
is further inserted into the equipment cabinet to its final position. 
BACKGROUND OF THE INVENTION 
In the electrical power distribution industry, as well as other industries, 
large equipment cabinets are provided containing electrical components 
that are electrically interconnected to other equipment in the cabinet. 
Some of these components, such as large circuit breakers, must be able to 
be temporarily disconnected and removed or simply disconnected and left in 
place. Such components are usually arranged on rails within the equipment 
cabinet which permit the component to slide into the equipment cabinet for 
electrical mating and out of the equipment cabinet for removal. For 
example, low voltage circuit breakers which handle up to about 600 volts 
AC and up to about 4000 amperes, are arranged to slide along the rails and 
are positionable in three distinct positions. In the first position the 
circuit breaker is within the equipment cabinet but not electrically 
mated. In the second position secondary contacts, which are used for 
control functions, are mated but the primary power contacts are spaced 
from their mating contacts, in the present example, a distance of 1.625 
inches. And in the third position both the secondary and primary contact 
are mated. These three positions are known in the industry as the 
disconnect position, test position, and connect position, respectively. As 
the circuit breaker is moved along the rails from the second to third 
positions, The secondary contacts must remain mated. To accomplish this 
one half of the secondary contact connector which is attached to the 
equipment cabinet has elongated contacts that extend along the direction 
of travel a distance greater than the 1.625 inches so that when the 
circuit breaker is in the test position the contacts of the connector 
attached to the circuit breaker are in engagement with respective ones of 
the elongated contacts. As the circuit breaker is moved toward and into 
its connect position, these secondary contacts slide along the elongated 
contacts and remain mated. These secondary contacts must be able to carry 
electrical loads of up to 600 volts AC or DC and current levels of up to 
10 amperes. Therefore, the elongated secondary contacts are relatively 
large having long contacting surfaces which are usually silver plated. 
Such contacts are costly to manufacture and require substantial room 
within the equipment cabinet. 
What is needed is a secondary connector having conventional length 
secondary contacts that will mate when the circuit breaker is moved from 
its disconnect position into its test position, and will remain mated 
while the circuit breaker is further moved into its connect position. 
Conversely, the secondary contacts must remain mated while the connector 
is moved from its connect position back into its test position, and should 
break contact when the circuit breaker is further moved from its test 
position to its disconnect position. 
SUMMARY OF THE INVENTION 
An electrical connector is coupled to an equipment cabinet and arranged to 
mate with a mating connector attached to a component that is inserted into 
an opening in the cabinet. The connector includes a first housing having a 
plurality of first electrical contacts arranged therein and adapted for 
mating along a mating axis of the connector with respective ones of a 
plurality of second electrical contacts in a second housing of the mating 
connector. The connector is coupled to the equipment cabinet by means of a 
coupling having a mounting surface for securing it to the cabinet. The 
coupling is arranged so that the connector is movable with respect to the 
mounting surface along the mating axis from an extended position to a 
retracted position while remaining mated to the mating connector.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
There is shown in FIG. 1 an equipment cabinet 10 of the type used for 
holding power switchgear for low voltage power distribution. The cabinet 
10 includes an array of bays 12 for holding circuit breakers 14 which are 
arranged to slide along rails 16 into and out of the bays. Each bay 12 
includes a door 18 that is hinged to the cabinet 10 and completely covers 
the open end of the bay when closed. The door 18 may be opened to gain 
access to the circuit breaker within the bay for maintenance, for placing 
the circuit breaker in operation, or for removing it from operation. While 
power switchgear is used to describe the present invention, it will be 
understood that this is by way of example only and that the teachings of 
the present invention may be advantageously utilized with other types of 
equipment as well. 
As best seen in FIG. 2 the circuit breaker 14 is shown fully within the bay 
12 in a first position, known as the disconnect position, with the door 18 
open. A primary electrical connector 20 is attached to structure of the 
cabinet 10 within the bay 12, and carries the power that is to be 
protected by the circuit breaker 14. A mating primary connector 22 is 
attached to and carried by the circuit breaker 14 for mating with the 
connector 20 when the circuit breaker 14 is fully inserted into the bay 12 
in a third position, known as the connect position, as will be explained 
in further detail below. A secondary electrical connector 24 is coupled to 
the cabinet 10 within the bay 12 by means of right and left coupling 
assemblies 26 and 26', respectively, which have mounting surfaces 28 and 
28' that are secured to brackets 30 by screws or other suitable means. A 
mating secondary connector 32 is attached to and carried by the circuit 
breaker 14 for mating with the connector 24 when the circuit breaker is in 
a second position, known as the test position, as will be explained below. 
The secondary connector 24 with its attached right and left coupling 
assemblies 26 and 26', is shown mated to the mating secondary connector 32 
in FIG. 3, and is shown without the mating connector 32 in FIG. 4. Note 
that both of these views omit the cabinet 10 and circuit breaker 14. The 
major elements of the mated connector, as shown in FIG. 3, are shown in 
exploded format in FIG. 5. The secondary connector 24, as shown in FIG. 5, 
includes a first housing 40 having a plurality of openings 42, each of 
which contains a respective first electrical contact 44. The contacts 44 
include terminals 46 to which conductors may be attached in the usual 
manner, for electrically interconnecting the contacts 44 to circuitry 
within the cabinet 10. The secondary connector housing 40, as best seen in 
FIGS. 6, 7, and 8 has its contact openings 42 arranged in three rows. Each 
opening 42 extends through the housing and terminates in another opening 
38 that receives the terminal 46 of each contact 44. A protective cover 
48, having turned down edges 50, is arranged to slidingly engage two 
channels 52 formed in the housing 40 and to cover the terminals 42, as 
shown in FIGS. 3 and 4. The mating secondary connector 32 includes a 
second housing 54 having a plurality of second contacts 56 arrange to mate 
with respective ones of the contacts 44. The contacts 56 include terminals 
58 to which conductors may be attached in the usual manner, for 
electrically interconnecting the contacts 56 to circuitry within the 
circuit breaker 14. A pair of alignment pins 60 project from the second 
housing 54 and serve to align the two connectors during mating by entering 
respective alignment openings 62 formed in the first housing 40 as the 
mating connector 32 moves along a mating axis 64. 
In the following discussion the right coupling assembly 26 will be 
described, however, it will be understood that the left coupling assembly 
26' is substantially identical having similar parts. The right coupling 
assembly 26 includes a U-shaped channel 68 having an elongated opening 70 
formed parallel to the mating axis 64. The channel 68 includes flanges 72 
and 74 containing holes 76 for receiving screws for securing the mounting 
surface 28 of the flange 72 to the bracket 30, as shown in FIG. 2. 
Optionally, a mounting surface 28' of the flange 74 may be similarly 
secured to the bracket 30 or other structure attached to the cabinet 10. 
The right coupling assembly 26 includes a mounting bracket 78 that is 
attached to the end of the first housing 40 by screws 80 or by any other 
suitable means such as staking or adhesive. A pair of pins 82 project 
outwardly from the mounting bracket 78 and through the elongated opening 
70 in the channel 68. The pins 82 are secured to the bracket 78 by means 
of reduced diameters 84 that extend through spaced holes 86 formed in the 
bracket and are peened over or otherwise deformed. Optionally, the pins 82 
may be attached directly to the ends of the housing 40 thereby eliminating 
the need for the mounting brackets 78. The attachment may be by any 
suitable means such as insitu molding or pressing separate pins into holes 
in the housing. Each pin 82 includes a roller 88 journaled for rotation 
thereon and, in the present example, held in place by an enlarged head 90. 
The rollers 88 have outside diameters that are sized to be received 
between the opposing surfaces of the two flanges 72 and 74, as shown in 
FIGS. 3 and 4. Each of the rollers 88, as best seen in FIGS. 9 and 10 
includes a hole 92 that is a slip fit with its respective pin 82 and a 
counterbore 94 that receives the head 90 with clearance. A hub 96 is 
formed on the opposite side of the roller and extends through the 
elongated opening 70 in the channel 68. Additionally, each roller 88 
includes a V-shaped groove 98 formed in its peripheral surface having a 
radius 100 at its apex. A U-shaped spring, made of wire having a 
cross-sectional radius that is equal to or less than the radius 100, is 
arranged so that a partial circular portion 112 wraps around the roller 88 
and nestles into the radius 100 at the apex of the V-shaped groove. The 
circular portion 112 wraps around the roller 88 an angular amount 114 in 
excess of 180 degrees, in the present example the angular amount is about 
210 degrees. In its free state, as viewed in FIG. 11, the portion 112 has 
an inside radius 116 that is slightly smaller than the radius 118 of the 
bottom of the V-shaped groove 98, as shown in FIG. 9. This permits the 
partial circular portion 112 to tightly engage the bottom of the V-shaped 
groove 98 for the full angular amount 114 when in the position shown in 
FIG. 4. The spring 108 has relatively long legs 120 and 122 extending from 
junctions 124 and 126, respectively. The legs 120 and 122 terminate in 
outwardly turned stub ends 128 and 130 that extend through clearance holes 
132 and 134 formed in the flanges 72 and 74, respectively. The purpose of 
these stub ends is to retain the spring 108 in proper alignment as the 
circuit breaker 14 is moved between its first, second, and third 
positions, as will be explained in more detail below. It will be noted 
that only one of the two rollers 88 on each side of the secondary 
connector 24 is in engagement with a spring 108. The other roller on each 
side need not have the V-shaped groove 98, and instead may have a simple 
cylindrically shaped surface, as desired. An advantage in having the 
V-shaped groove in all rollers is that there are fewer different parts to 
manufacture and inventory. 
The operation of the secondary connector 24 and coupling assemblies 26 and 
26' will now be described with reference to FIGS. 2, and 9 through 14. As 
shown in solid lines in FIG. 2, the circuit breaker 14 is in its first or 
disconnect position within the bay 12 where both the primary connectors 
20, 22 and the secondary connectors 24, 32 are unmated. In this position 
the secondary connector 24 and mating connector 32 are separated by a 
distance of about 0.500 inch. As the circuit breaker 14 is moved toward 
the right along the rails 16 it moves into its second or test position, 
shown in phantom lines 136 in FIG. 2. During this movement of the circuit 
breaker the secondary mating connector 32 moves from the position shown in 
FIG. 12, toward and into engagement with the secondary connector 24, and 
finally into full mated engagement therewith as shown in FIG. 13. There 
are normally about 60 contacts 44 in the secondary connector 24, each 
having a maximum mating force of about one half pound, resulting in a 
total mating force for the secondary connector of about 30 pounds or less. 
However, in certain cases there may be as few as five or six contacts 44 
resulting in a total mating force for the secondary connector of about 3 
pounds or less. The two springs 108 resist this mating force by virtue of 
their circular portions 112 being in engagement with the V-shaped grooves 
98 of their respective rollers 88, as shown in FIG. 13. This prevents 
movement of the secondary connector 24 along the mating axis 64 during 
this mating with the mating connector 32. At this point the primary mating 
connector 22 is still spaced from the primary connector 20 by a distance 
138 that is equal to about 1.625 inches. As the circuit breaker 14 is 
further moved along the rails 16 toward the right, as viewed in FIG. 2, 
the right most rollers 88, as viewed in FIG. 13 are forced against the 
junctions 124 and 126 causing the circular portion 112 to expand so that 
the legs 120 and 122 move apart, the stub ends 128 and 130 simply 
extending further through their respective holes 132 and 134. When the 
circular portion 112 expands sufficiently far, the distance between the 
two junctions 124 and 126 is great enough to allow the roller 88 to pass 
and move toward the right to the position shown in FIG. 14, which is the 
third or connect position of the circuit breaker 14, as shown in phantom 
lines 140 in FIG. 2. As the roller 88 moves from the position in FIG. 13 
to the position in FIG. 14 the V-shaped groove 98 of the roller tracks 
along the legs 120 and 122 and maintains the spring 108 in proper 
alignment. Additionally, during this movement there is very little 
resistance offered by the spring 108 as the circuit breaker is moved from 
its test position to its connect position. It is important that the angle 
114 of the circular portion 112 be chosen so that the junctions 124 and 
126 are effective in inhibiting movement of the secondary connector 24 
along the mating axis 64 while the mating connector 32 is moved into 
mating engagement therewith, but will allow these junctions to separate 
sufficiently so that the circuit breaker 14 can be moved from its test 
position to its connect position without further substantial resistance 
from the couplings 26 and 26'. When the circuit breaker 14 is moved from 
its connect position shown in FIG. 14 and in phantom lines 140 in FIG. 2, 
to its test position shown in FIG. 13 and in phantom lines 136 in FIG. 2, 
the rollers 88 simply track along the legs 120 and 122 of the springs 108 
until they fully engage the circular portions 112, as best seen in FIG. 
13. Importantly, during this movement there is very little resistance 
offered by the spring 108 so that the secondary connector 24 is pulled 
along with the mating connector 32 without danger of unmating, even in the 
case where a low pin count results in a relatively low mating force. It 
will be appreciated that the spring 108 and associated roller 88 are 
uniquely arranged to provide a maximum of resistance in one direction and 
a minimum of resistance in the opposite direction. The maximum resistance 
is required when a 60 pin mating connector 32 is moved into mating 
engagement with a 60 pin connector 24. The minimum resistance is required 
during movement of the circuit breaker from the connect position to the 
test position when the connector has only 5 or 6 pins resulting in only 3 
pounds of mating force to hold the two connectors together. At this point 
the circuit breaker is in the test position with the secondary connectors 
24 and 32 still mated and the primary connectors 20 and 22 disconnected 
and spaced apart by the distance 138. When the circuit breaker 14 is moved 
from its test position to its disconnect position, shown in FIG. 12 and in 
solid lines in FIG. 2, the two springs 108 retain the secondary connector 
24 in position with respect to their respective U-shaped channels 68 so 
that the mating connector 32 must disengage during the last portion of the 
movement of the circuit breaker. 
An important advantage of the present invention is that the contacts of the 
secondary connector are of conventional length and will mate when the 
circuit breaker is moved from its disconnect position into its test 
position, and will remain mated while the circuit breaker is further moved 
into its connect position, or conversely when it is moved from its connect 
position to its test position. This substantially reduces the overall size 
of the secondary connector and importantly reduces its cost to manufacture 
and to maintain. Further, in the case where the total mating force is 
relatively low due to a low pin count, the mating force is still 
sufficient to overcome the resistance of the spring and roller to hold the 
mated secondary connectors in mated engagement while the circuit breaker 
is moved from its connect position to its test position.