Method and quick-disconnect apparatus for a three-phase motor

The present invention provides a method and quick-disconnect apparatus for disconnecting power to a three-phase motor. The present invention provides a quick-disconnect apparatus for efficiently and easily disconnecting three-phase power to a motor having a receptacle terminal box with a first plurality of quick-disconnect receptacles, a second plurality, half of the first plurality in number, of bus bars connecting pairs of the quick-disconnect receptacles, and the second plurality of power cables individually connected to the bus bars for providing current to the three-phase motor.

BACKGROUND OF THE INVENTION 
The present invention is directed generally to a three-phase motor and, 
more specifically, to a method and a quick-disconnect apparatus for 
disconnecting and reconnecting power to a three-phase motor. 
Much of today's heavy duty machinery requires three-phase power. Examples 
include motor-driven pumps, motors and generators in power plants, 
refineries and steel mills. In addition, the cables necessary for 
providing adequate power to the machinery must be extremely large to 
accommodate the massive currents used in some of the three-phase motors. 
As a result, many three-phase motors used to operate heavy duty machinery 
require a number of very bulky, large and inflexible cables. 
Several problems are known when dealing with such a large number Of missive 
power cables in a large heavy industry plant especially when several 
three-phase motors are in use. For example, large cable trays are used to 
guide the cables between pieces of equipment and the main power supply for 
the equipment in the plaint. While these cable trays are able to keep a 
large number of power cables neatly organized from the power supply to the 
individual motors and other pieces of equipment using three-phase power, 
other problems are commonplace. 
For example, it is a known problem at the actual motor itself, where the 
cables leave the cable tray and are loose, to provide an acceptable 
solution for organizing and connecting the cables. The large cables are 
bulky and less flexible and as a result cause difficulties in organizing 
and connecting the cables at the three-phase motor. In addition, to 
complicate matters, some heavy duty motors require very large currents 
that are beyond the capability of the standard power cables. Thus, in 
these instances, a particular motor will require a parallel feed of 
three-phase power. Thus, the number of power cables is at least doubled to 
provide the adequate current needed for the three-phase motor. 
In addition, some of these motors can be as large as a tanker trailer on a 
semi and have horsepower ratings of several thousand horsepower. As a 
result, typically many heavy-duty motors require connections to several 
bulky power cables at a junction box for the motor. These cables are often 
spliced together (known as "bugging") with heavy-duty rubber tape and PVC 
tape. However, these spliced cables form an unwieldy bundle at the motor 
that is difficult to work with and cumbersome to disconnect (i.e., 
"un-bug"). For example, if a motor needs to be replaced, a time consuming 
disconnection of the spliced together massive power cables 
("un-bugging"and "re-bugging") greatly increases the time needed to 
replace the motor. For example, a typical "un-bugging" procedure requires 
a full shift for two skilled workers. In addition, a typical "re-bugging" 
procedure requires a shift and a half for two workers. 
Thus, a method and apparatus for providing quick-disconnects for 
efficiently and neatly disconnecting power to a three-phase motor 
(un-bugging and re-bugging) is needed in the field of heavy industry. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a method 
and apparatus for quick-disconnecting power to a three-phase motor 
(un-bugging and re-bugging) requiring greatly reduced effort and time. 
The present invention provides a method and quick-disconnect apparatus for 
disconnecting and reconnecting power to a three-phase motor. The method 
provides for quickly disconnecting the power to a three-phase motor 
without using extraneous tools. The method has steps of providing a power 
junction box with a plurality of electrical receptacles and a plurality of 
power cables connected to the receptacles. For example, three power cables 
are connected at one end to a bus bar. The bus bar is connected to the 
power cables of the receptacles, and the other end of the three power 
cables is connected to the three-phase motor itself. 
The present invention also provides a quick-disconnect apparatus for a 
three-phase motor having a receptacle terminal box with a first plurality 
of quick-disconnect receptacles. The apparatus also has a second plurality 
(half of the first plurality) of bus bars for connecting pairs of the 
quick-disconnect receptacles to each other. Also, the quick-disconnect 
apparatus provides a plurality of power cables individually connected to 
the bus bars for providing current to the motor. 
The present invention provides, in an embodiment, a quick disconnect 
apparatus for a high voltage, high current three phase motor, to be 
positioned between electrical motor power cables connected to the motor 
for supplying electrical power thereto and electrical power cables 
connected to a source of electricity, having a junction box having at 
least one exposed wall, a plurality of quick disconnect connectors; one 
half of each of the connectors being mounted through the exposed wall of 
the junction box so as to be accessible from both an interior and an 
exterior of the junction box and a second half of each of the connectors 
being mounted on an end of each of the electrical power cables, and means 
for mechanically connecting each of the motor power cables from the motor 
to an appropriate one of the quick disconnect receptacles within the 
junction box.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures, FIG.1 illustrates a quick-disconnect for a 
apparatus for a three-phase motor of the present invention. The 
quick-disconnect apparatus 10 is shown mounted to a three-phase motor 11. 
The type of motor contemplated to be used with the present invention 
ranges from 480 volts to 550 volts, all the way to 5 kilovolts and up. The 
motors can be three-phase with delta connections. The electrical currents 
involved in the motors of this size can be up to 1000 amperes. As 
illustrated, the quick-disconnected apparatus 10 has a junction box 12 
with a cover 13. The cover 13 is affixed to the junction box 12 for 
example, by screws 14. The junction box 12 has a connector panel 15 having 
a plurality of quick-disconnect receptacles 16 (see FIG. 2). Connected to 
these receptacles 16 are a plurality of power cables 17. The power cables 
17 have quick-disconnect plugs 18 at one end for connecting to the 
quick-disconnect receptacles 16 of the present invention. The 
quick-disconnect plugs 18 are of the type commonly used in temporary 
situations for welding, lighting and related uses. The other ends of the 
power cables 17 are usually routed through cable trays (not shown) to the 
supply of electrical power. Typical sizes for the power cables 
contemplated for use with the present invention are 500/750/1000 Thousand 
Circular Mils, (MCM). These cables have diameters on the order of one and 
a half inches and larger. 
Referring now to FIG. 2, the quick-disconnect apparatus 10 is illustrated 
in a front cutaway view. The junction box 12 is shown with a cut-away of 
the cover 13 affixed by screws 14. Also illustrated in FIG. 2 are the 
quick-disconnect receptacles 16 shown mounted to the connector panel 15 of 
the quick-disconnect apparatus 10. Also illustrated is a connector end 19 
of the quick-disconnect receptacle 16. At the other end of the 
quick-disconnect receptacle 16 is a bus bar 20 which is secured to the 
quick-disconnect receptacle 16 by nuts 21. The bus bar 20 electrically 
Connects pairs of the quick-disconnect receptacles 16. 
In a preferred embodiment, six quick-disconnect receptacles 16 are provided 
in the quick-disconnect apparatus 10. Also, three bus bars 20 connect the 
six quick-disconnect receptacles 16 into three pairs. Also, illustrated in 
FIG. 2 are three motor power cables 22. A connector 24 is located at one 
end of each of the motor power cables 22. This connector 24 electrically 
connects to the bus bar 20 which is connecting the pair of 
quick-disconnect receptacles 16 and is secured thereto by the nuts 21. As 
illustrated, three motor power cables 22 are shown connected to the three 
pairs of quick-disconnect receptacles 16. The other end of each of the 
three motor power cables 22 connects to the three phase motor 11. In an 
embodiment, the three motor power cables 22 feed through an exposed wall 
or a cut-out 25 of a back parcel 26 of the junction box 12. 
Referring now to FIG. 3, the bus bars 20 are illustrated in a sectional 
view taken along line III--III of FIG. 2 of the present invention. As 
illustrated, the bus bars 20 are secured to a threaded stud 27 of the 
quick-disconnect receptacle 16 by the nuts 21 and a washer 28. In the 
embodiment shown, three bus bars 20 are shown connecting six 
quick-disconnect receptacles 16 to form three pairs of quick-disconnect 
receptacles 16. However, more are possible to satisfy increased current 
draws needed for motors having greater demands. 
Also, illustrated in FIG. 2, are the three motor power cables 22. These 
motor power cables 22 are connected via the connector 24 to the threaded 
stud 27 and the bus bar 20 of each pair of quick-disconnect receptacles 
16. The motor power cables 22 are shown exiting the cut-out 25 of the 
junction box 12. 
FIG. 4 illustrates a side sectional view taken along line IV--IV of FIG. 3 
of the present invention. A pair of quick-disconnect receptacles 16 are 
shown connected via the bus bar 20 and secured by the nuts 21. Also 
illustrated are quick-disconnect plugs 18 which insert into the connector 
end 19 of the quick disconnect receptacle 16. The quick-disconnect plugs 
18 are each individually connected to a power cable 17. Each power cable 
17 is provided with a grasping means 29 for a user to pull on when 
disconnecting the plug 18 from the quick-disconnect receptacle 16 of the 
present invention. Once a user has separated the quick-disconnect plug 18 
from the quick-disconnect receptacle 16, the power cable 17 becomes free 
as shown by the dashed version 30 of the power cable 17. At this point, 
the remaining connected power cables 17 can be similarly disconnected to 
replace a motor. 
To operate the quick-disconnect apparatus 10; a user simply separates the 
power cable 17 from the quick-disconnect apparatus 10 by separating the 
quick-disconnect plug 18 from the quick-disconnect receptacle 16 for each 
power cable 17. This operation can be carried out in any number of 
different ways depending on the type of connectors used. For example, the 
present invention can be embodied using 500 MCM size E1017 Series 
CAM-LOK.RTM. plugs and receptacles, which require only a third of a turn 
to disconnect the plugs 18 from the receptacles 16. 
The power cables 17 can be easily reconnected after a motor has been 
replaced by basically reversing the disconnecting process. In this manner, 
the present invention provides a quick and efficient method and apparatus 
for disconnecting and reconnecting power cables when a motor needs 
replacing, for instance. 
Although the invention has been described with respect to preferred 
embodiments, it is not to be so limited as changes and modifications can 
be made therein which are within the full intended scope as defined by the 
appended claims.