U.S. patent number 3,806,846 [Application Number 05/376,459] was granted by the patent office on 1974-04-23 for pushbutton reset undervoltage release device.
This patent grant is currently assigned to General Electric Company. Invention is credited to David B. Powell.
United States Patent |
3,806,846 |
Powell |
April 23, 1974 |
PUSHBUTTON RESET UNDERVOLTAGE RELEASE DEVICE
Abstract
An electric circuit breaker is provided with an undervoltage
release having a manual reset button independent of the handle used
for manually opening and closing the circuits controlled by the
circuit breaker. The undervoltage release device includes a
solenoid plunger movable between a seated position and a released
position and a tripping member movable into and out of a tripping
position in response to the movement of the plunger. The reset
button operates on an actuator lever operatively associated with
the separate tripping member and plunger so that upon actuation of
the button the tripping member is urged toward a tripping position
and the plunger is urged toward the seated position.
Inventors: |
Powell; David B. (Bristol,
CT) |
Assignee: |
General Electric Company (New
York, NY)
|
Family
ID: |
23485113 |
Appl.
No.: |
05/376,459 |
Filed: |
July 5, 1973 |
Current U.S.
Class: |
335/20;
335/166 |
Current CPC
Class: |
H01H
83/12 (20130101) |
Current International
Class: |
H01H
83/00 (20060101); H01H 83/12 (20060101); H01h
083/12 () |
Field of
Search: |
;335/20,27,26,166 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: Cahill; Robert A. Schlamp; Philip
L. Neuhauser; Frank L.
Claims
I claim:
1. An electric circuit breaker comprising a casing, a handle
extending through the casing for manually opening and closing the
circuits controlled by the circuit breaker, a trip unit in the
casing operable to effect automatic opening of said circuits, a
trip control unit adjacent the trip unit for controlling the
tripping operation of the trip unit including a tripping member
movable toward a tripping position for tripping the trip unit, an
automatic trip actuator movable between an electrically responsive
seated position and a released position and operable upon movement
toward its released position to cause movement of the tripping
member toward its tripping position, said trip actuator in its
released position being operative to prevent movement of the
tripping member out of its tripping position, and a reset operator
independent of the handle and movable between a reset position and
an operating position and operative upon movement toward said
operating position to urge the tripping member toward its tripping
position and the actuator toward its seated position.
2. The circuit breaker of claim 1 wherein the trip control unit
includes a solenoid operative upon energization to a predetermined
level to retain the trip actuator in its seated position and
actuator drive means effective upon a predetermined reduction in
the level of said energization to drive the actuator out of its
seated position toward its released position to trip the circuit
breaker.
3. The circuit breaker of claim 1 wherein the reset operator
includes a reset button operative upon actuation to prevent
movement of the tripping member out of its tripping position and to
drive the trip actuator into its seated position to effect
resetting of the trip control unit.
4. The circuit breaker of claim 1 wherein the reset operator
includes a reset button operative upon actuation to drive the
tripping member toward its tripping position while the trip
actuator is in its seated position.
5. The circuit breaker of claim 1 including actuator drive means
operative on the trip actuator for driving the actuator toward its
released position and tripping member drive means interconnecting
the tripping member and the actuator for driving the tripping
member out of its tripping position toward a retracted position
upon movement of the actuator to its seated position.
6. The circuit breaker of claim 1 including a reset lever
operatively connected with the reset operator and responsive to
movement of the trip actuator toward its released position to
change the position of the reset operator for indicating the
tripped condition of the circuit breaker.
7. The circuit breaker of claim 1 including a reset lever in
driving engagement with the trip actuator, an actuating lever
interconnecting the reset operator with the reset lever and the
tripping member, and spring means biasing the tripping member
toward the trip actuator, said actuating lever being operative to
restrain movement of the tripping member out of its tripping
position upon movement of the reset operator toward its operating
position and to impart a driving force to the reset lever to cause
the reset lever to drive the trip actuator toward its seated
position against the bias of said spring means to effect resetting
of the trip control unit.
8. The circuit breaker of claim 1 wherein the tripping member is in
axial alignment with the trip actuator and is operable between a
tripping position and a retracted position, said actuator being
operative during movement toward its released position to drivably
engage said tripping member and drive said member toward its
tripping position, said unit including a tripping lever connected
to said tripping member for driving said member toward its tripping
position independently of said actuator.
9. The circuit breaker of claim 8 including an actuating lever
operatively interconnecting the reset operator and the tripping
lever for driving the tripping lever to effect tripping upon
movement of the reset operator to its operating position.
10. The circuit breaker of claim 1 wherein the reset operator is a
manually operated member protruding through the casing at a
location spaced from the handle.
11. For use with an electric circuit breaker having an ON/OFF
handle for opening and closing the circuits controlled by the
circuit breaker and a trip unit for effecting automatic opening of
said circuits, an electrically responsive trip control unit for
controlling the tripping operation of the trip unit including a
tripping member movable toward a tripping position for tripping the
trip unit, an automatic trip actuator including a plunger movable
between an electrically responsive seated position and a released
position and operable upon movement toward its released position to
cause movement of the tripping member toward its tripping position,
said plunger in its released position being operative to prevent
movement of the tripping member out of its tripping position, and a
reset operator independent of the handle and movable between a
reset position and an operating position and operative upon
movement toward said operating position to urge the tripping member
toward its tripping position and the plunger toward its seated
position.
12. The trip control unit of claim 11 wherein the automatic trip
actuator includes drive means for driving the plunger toward its
released position, and a solenoid operative on said plunger for
retaining said plunger in its seated position against the driving
action of said drive means, said solenoid being ineffective in
retaining said plunger upon the occurrence of a predetermined drop
in the voltage applied to the solenoid.
13. The trip control unit of claim 11 including a reset lever
operatively connecting the plunger and the reset operator and a
plunger drive spring for driving the plunger toward its released
position, said reset lever being responsive to movement of the
reset operator toward its operating position to drive the plunger
toward its seated position against the bias of the plunger drive
spring for resetting the trip control unit.
14. The trip control unit of claim 11 including a tripping lever
connected to the tripping member for movement therewith, an
actuating lever drivably connecting the tripping lever and the
reset operator and a tripping member return spring biasing the
tripping member toward the plunger, said actuating lever being
responsive to movement of the reset operator toward its operating
position to drive the tripping lever and tripping member away from
the plunger against the bias of said return spring.
15. The trip control unit of claim 11 wherein the reset operator is
a manually operated button accessable from the exterior of the
circuit breaker and spaced from the ON/OFF handle.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates generally to electric circuit
breakers. More particularly is is concerned with a new and improved
electric circuit breaker having an undervoltage release type device
responsive to a decrease in line voltage within a circuit
controlled by the breaker.
Undervoltage release type devices utilized heretofore have commonly
employed a solenoid retained actuator or plunger that is held by
the solenoid during normal operation and is released in response to
a predetermined drop in the line voltage. Typically the plunger is
reseated or reset by the opening or tripping movement of some part
of the breaker mechanism. As a result a common problem has existed
with undervoltage release devices; namely, the reversal of this
tripping motion or a release of the reseated plunger must take
place before the undervoltage release device can trip the breaker
latch. Consequently, if an undervoltage condition persists and the
circuit breaker is moved to its ON position, a race occurs between
latch release by the undervoltage release device and movement of
the contacts toward their closed circuit positions. This becomes
particularly critical in mining use applications. Under such use it
is extremely important for safety reasons that there be no
re-energization of the cable which originally signaled the
undervoltage release device until that cable has been repaired.
Although many different approaches have been used in solving this
problem, none has been completely satisfactory. According to one
approach, a fine adjustment of the mechanism makes it possible to
cause latch release and therefore tripping early enough to prevent
the contacts from re-energizing the line. However, such an
adjustment puts a heavy strain on the mechanism since maximum
energy is imparted to the links and pivots of the mechanism by such
an adjustment.
According to another method, the reset motion of the breaker handle
between the OFF and RESET positions is utilized to provide the work
necessary to reset or reseat the solenoid plunger. While this is
more practical in some breakers than others, it also requires
accurate parts and fine controls and further requires interphase
mechanical connections. Additionally, electrical reset schemes have
been tried with or without switching but these techniques have also
encountered difficulty for various reasons.
Accordingly, it is an object of the present invention to provide a
new and improved electric circuit breaker having an undervoltage
tripping device that prevents resetting or reseating of the
undervoltage release while the undervoltage condition persists.
Included in this object is the provision for a new and improved
undervoltage trip control device that requires a separate and
distinct resetting action not associated with the main ON/OFF
handle of the circuit breaker.
Another object of the present invention is to provide a new and
improved electric circuit breaker of the type described including
an undervoltage trip control device constructed so as to make it
impossible to reset the trip latch of the circuit breaker while the
solenoid is in a low voltage or de-energized condition.
Still, another object of the present invention is to provide an
undervoltage trip control device that requires the operator of the
breaker to supply a separate resetting force while at the same time
preventing any attempts to defeat the undervoltage release function
of the unit.
A further object of the present invention is to provide a new and
improved circuit breaker of the type described including an
undervoltage trip control device that has no interphase mechanical
connections yet permits tripping of the breaker from the ON or OFF
positions with the solenoid energized.
A still further object of the present invention is to provide a new
and improved electric circuit breaker and undervoltage trip control
device of the type described that indicates a breaker tripping
condition by means of a separate button position.
Still another object of the present invention is to provide a new
and improved electric circuit breaker and undervoltage trip control
device of the type described which is compact, efficient, simple
and relatively trouble free.
Other objects will be in part obvious and in part pointed out in
more detail hereinafter.
These and related objects are accomplished in accordance with the
present invention by providing an electric circuit breaker of the
type described having a casing, a handle extending through the
casing for manually opening and closing the circuit controlled by
the circuit breaker, a trip unit in the casing operable to effect
automatic opening of the circuits and a trip control unit adjacent
the trip unit for controlling the tripping operation of the trip
unit. The trip control unit includes a tripping member movable
toward a tripping position for tripping the trip unit. An automatic
trip actuator is movable between an electrically responsive seated
position and a released position and is operable upon movement
toward its released position to cause movement of the tripping
member toward its tripping position. The actuator in its released
position is operative to prevent movement of the tripping member
out of its tripping position. A manual reset operator extends
through the casing independent of the handle and is movable between
a rest position and an operating position and is operative upon
movement toward said operating position to urge the tripping member
toward its tripping position and the actuator towards its seated
position.
A better understanding of the invention will be obtained from the
following detailed description and the accompanying drawings which
set forth an illustrative embodiment indicative of the way in which
the principles of the invention are employed.
A BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
FIG. 1 is a side elevation view partially broken away and partially
in section of a molded case circuit breaker incorporating the
undervoltage release device of the present invention;
FIG 2 is a partial top view of the circuit breaker of FIG. 1
showing the location of the independent reset button for manual
actuation of the release device;
FIG. 3 is an enlarged top view of the undervoltage release device
of the present invention;
FIG. 4 is a side view of the undervoltage release device of FIG. 3
showing the device during normal closed circuit operation of the
breaker;
FIG. 5 is a view similar to FIG. 4 showing the undervoltage trip
control device in its fully tripped condition in response to a low
voltage or no voltage condition; and
FIG. 6 is a view similar to FIG. 4 showing the undervoltage trip
control device upon manual actuation of the device's reset
button.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawing in greater detail wherein like
reference numerals indicate like parts throughout the several
figures, the invention is shown as incorporated in an electric
circuit breaker including a generally rectangular insulating case
comprised of a base portion 10 and a cover portion 12. The
particular circuit breaker illustrated is a three pole circuit
breaker and comprises three elongated chambers or current paths
each of which contain separable contacts (not shown) of a
conventional type. The operating mechanism which controls movement
of the separable contacts between open and closed circuit positions
is controlled by a manually operated handle 14 projecting centrally
from the top of cover 12 for movement between its ON and OFF
positions. The operating mechanism includes a trip unit 16 such as
that described and illustrated in U.S. Pat. No. 3,162,740, the
disclosure of which is incorporated herein by reference, and a
normally restrained but releasable member (not shown) which is
adapted to be releasably held by a trip bar 18 housed within unit
16. The bar 18 extends fully across the circuit breaker and is
mounted for pivotal movement between a latched position and a
tripped position where it effects simultaneous opening of all three
current paths controlled by the circuit breaker.
For the purpose of initiating a tripping operation of the trip unit
upon the occurence of a predetermined decrease in voltage in a
selected circuit controlled by the breaker, an undervoltage trip
control device is provided as indicated generally in FIG. 1 by the
numeral 20. The undervoltage release device 20 is enclosed within
the casing and is operatively associated with a reset button 22
that projects upwardly through an aperture 24 in the casing cover
12 intermediate the manual handle 14 and the side of the casing. In
the embodiment illustrated the protruding portion of button 22 is
enclosed by a deformable dust cap 26 attached to a cylindrical
sleeve or guide 28 secured to the cover 12 at the aperture 24.
Referring now to FIGS. 3-6, the undervoltage trip control or
release device is shown as comprised of a generally flat sheet
metal supporting frame having a central planar portion 30 with an
enlarged circular aperture 32 adjacent one end thereof for registry
with the reset button aperture 24 in the cover of the circuit
breaker's casing. The support includes front and rear end walls 34,
36 respectively that are bent in opposite directions at
approximately 90.degree. to the central planar portion 30 and
provide appropriate means for mounting the entire undervoltage trip
control unit within the circuit breaker. In this connection, the
front bent-up end wall 34 is preferably mounted on the trip unit 16
of the circuit breaker and secured thereto by means of a suitable
threaded connector 38. Side flanges 42, 44 depend downwardly from
the central planar portion 30 of the support and provide means for
mounting the movable components of the trip control unit.
A tripping lever 46 is pivotally mounted on the depending side
flange 42 adjacent the upstanding front wall 34 by means of fixed
pin 48 and in turn is pivotally connected by pin 50 to a flat sheet
metal slide member 52. In the embodiment illustrated the member 52
is provided with an elongated tripping plunger portion 54 adapted
to extend into the trip unit 16 for tripping contact with the trip
bar 18. As best shown in FIGS. 4-6, the tripping lever 46 is a
generally triangular member with the aforementioned pivotal
connections at two of its three corners and the free corner 56
thereof positioned remotely from front wall 34 in such a manner
that pivotal movement of the tripping lever 46 about the fixed
pivot pin 48 in a counterclockwise direction as viewed in FIG. 4
will drive the slide member 52 to the left as viewed in FIG. 4 so
as to bring the plunger portion 52 into engagement with the trip
bar 18. As shown, the slide member 52 is also provided with a
linear elongated slot or guideway 58 within which is positioned a
laterally extending guide tab 60 located generally within the plane
of the main body portion 30 of the support and extending laterally
therefrom. In this manner, the slide 52 is restrained to travel
along a reciprocally linear path during movement between its
retracted and advanced positions in response to the pivotal
movement of the tripping lever 46.
A solenoid 62 is positioned in operative alignment with the
elongated slide member 52 and is rigidly mounted on the support
adjacent the rear depending wall 36 by threaded connectors 64. The
solenoid is provided with a generally cylindrical plunger 66
fixedly mounting a flat guide plate 68 on its free end for
restrainably confining a plunger drive spring 70 coiled around the
plunger between the plate 68 and the solenoid 62. The guide plate
68 is provided with top and bottom notches 72 and the reciprocating
slide member 52 is provided with an enlarged recess 74 adjacent its
rearward end and above guideway 58 so that the slide 52 and the
plate 68 on the solenoid plunger interfit for relative sliding
movement while cooperating to provide coaxial alignment
therebetween.
A tripping plunger return spring 76 is connected at one end to the
guide plate 68 and at its opposite end to the pivot pin 50
interconnecting the guide plate 68 with the slide member 52. Thus,
as will be appreciated, the slide member and the solenoid plunger
may move independently or in unison between their respective
extended or retracted positions. However, when the solenoid plunger
is in its retracted or seated position and the slide member is in
its extended or tripping position, the tripping plunger return
spring 76 will be in its extended or loaded condition. Accordingly,
unless the slide 52 is restrained, the return spring 76 will bias
the slide toward the solenoid plunger after the latter has moved to
its seated position. Therefore, as the solenoid plunger is moved
under the influence of its drive spring 70 out of its seated
position toward its extended position, the guide plate 68 will
drivably move the slide member 52 to the left as viewed in FIG. 4
toward its extended or tripping position shown in FIG. 5.
Also pivotably mounted on the support is the mechanism employed in
resetting or reseating the solenoid plunger 66 after it has been
released by an undervoltage condition. As mentioned hereinbefore,
the resetting mechanism includes a reset button 22 extending
through a reset aperture 24 in the cover 12 of the casing
intermediate the manual ON/OFF lever 14 and side wall of the
casing. The aperture 24 in the cover is preferably provided with a
tubular guideway 28 supportably mounted on the cover 12 and
enclosed by a resilient dust cover or cap 26 that lockably
interfits over the tubular guideway 28. The reset button 22 of
rod-like construction is slideably mounted within the guide 28 and
extends into the interior of the circuit breaker so as to pass
through the circular opening 32 in the central planar portion 30 of
the support for the undervoltage trip device.
The reset mechanism of the trip control device includes a sheet
metal accelerator plate 80 pivotably mounted on a pin 82 extending
between the depending flanges 42, 44 of the support so that the
free end of the plate underlies the aperture 32 and is engaged by
the reset button 22. A flat sheet metal resetting lever 84 is also
mounted on the pin 82 for pivotable movement and includes a first
uppermost leg portion 86 which extends upwardly from the pin 82 for
engagement by its free end with the guide plate 68. A second leg
portion 88 of the resetting lever 84 extends downwardly at an angle
slightly greater than 90.degree. relative to the first leg portion
and is pivotably connected by pin 90 at its end to a spaced
actuating lever 92 having an elongated slot 94 therein through
which passes the mounting pin 82. The flat sheet actuator lever 92
is disposed so as to be contacted by the free end of the
accelerator plate 80 at the end 96 of the actuator remote from the
elongated slot 94. The opposite end of the actuator lever, that is,
the end adjacent the elongated slot 94 and remote from the pin 90
is provided with a drive dog 98 adapted to contact the free corner
56 of the triangular tripping lever 46 to effect counterclockwise
pivotable movement of the tripping lever toward its tripping
position.
In FIG. 4 the parts are shown in the positions which they occupy
during normal operation of the circuit breaker. In this condition
the solenoid plunger 66 is held in its retracted or seated position
within the solenoid 62 while it is energized by the operating
referenced voltage. The slide member 52 and its associated
elongated tripping plunger portion 54 is held in its retracted
position by the biasing action of the trip return spring 76 and the
tripping lever 46 is positioned so that the free corner 56 thereof
bears against the dog 98 of the actuating lever 92. Additionally in
this condition the reset button 22 rests on accelerator plate 80
and tends to hold the leg 86 of reset lever 84 against guide plate
68.
If the voltage applied to the solenoid decreases a predetermined
amount, such as to a level of about 60 percent of its referenced
voltage, the plunger 66 will "fall out," that is, will be driven
outwardly from its seated position by the driving action of the
drive spring 70. The guide plate 68 will bear against the coaxially
aligned slide member 52, driving the member 52 to the left as
viewed in FIG. 4 and simultaneously rotating the tripping lever 46
counterclockwise as viewed in FIG. 4 causing the tripping plunger
54 to operate against the trip bar 18 and effect tripping of the
circuit breaker. At the same time, the guide plate 68 drives the
arm 86 of the reset lever 84 counterclockwise as viewed in FIG. 4
about its fixed pivot pin 82. The simultaneous pivotal movement of
the tripping lever 46 and reset lever 84 elevates the actuator
lever 92 as well as the accelerator plate 80 and reset button 22.
As a result, the undervoltage trip control device 20 assumes the
position shown in FIG. 5 when the circuit breaker is in its trip
condition and the reset button indicates the tripped condition by
its elevated position. Since the solenoid plunger drive spring 70
will continue to urge the tripping plunger 54 toward its tripped
position until the plunger 66 is reseated, movement of the manually
operated handle 14 between its ON and OFF positions will be
ineffective to close the contacts of the circuit breaker. Thus the
operator is required to perform the positive act of pushing the
reset button in order to reset or reseat the plunger prior to
turning the manual handle 14 of the circuit breaker to its ON
position.
The separate and distinct reset action required in the circuit
breaker of the present invention can be effected by depressing the
reset button 22 to drive the accelerator plate 80 clockwise about
its pivot pin 82 thereby simultaneously driving the free end 96 of
the actuating lever 92 downwardly or clockwise as viewed in FIG. 5.
As will be appreciated, the dog 98 on the end of the actuating
lever 92 firmly engages the free corner 56 of the tripping lever 46
to assure that the tripping plunger 54 is held in its tripping
position during the resetting operation. Additionally, the
clockwise movement of the actuator lever 92 will impart clockwise
movement to the resetting lever 84 causing the uppermost leg 86
thereof to bear against the guide plate 68 driving it rearwardly
against the bias of its drive spring 70 toward its seated position.
This will also load the slide member return spring 76 since the dog
end 98 of the actuator lever 92 will continue to retain the
tripping plunger 54 and pin 50 in their tripped position.
So long as the undervoltage condition persists, the solenoid will
be ineffective in retaining the plunger 66 in its seated position
and release of the reset button 22 will permit the plunger drive
spring 70 to drivably return the plunger to its extended position.
Once the undervoltage condition is corrected, the trip control unit
20 can be reset by depressing the reset button 22 to drive the
plunger to its reset or reseated position and load the tripping
plunger return spring 76. This condition of the device is shown in
FIG. 6.
The correction of the undervoltage condition permits the solenoid
to retain the plunger in its seated position so that the release of
the reset button 22 permits clockwise movement of the tripping
lever 46 as the slide member 52 is drawn to the right as viewed in
FIG. 6 under the driving action of the loaded tripping plunger
return spring 76. The withdrawal of the tripping plunger 54 will
permit resetting of the trip bar 18 thereby enabling the operator
to manually operate the ON/OFF handle 14 to the ON position.
It is an advantageous feature of the present invention that the
separate reset button described herein will permit tripping of the
circuit breaker from either an ON or OFF position with the solenoid
energized. Thus, if the undervoltage trip control device is in the
position shown in FIG. 4 with the solenoid in an energized
condition and the plunger 66 held in its seated position, an
operator may trip the circuit breaker by simply depressing the
reset button 22. Since the reset lever 84 is restrained against
clockwise movement by the contact of its upper leg 86 with the
guide plate 68, the actuator lever 92 will pivot about the pivotal
connection 90 so that the dog end 98 of the actuator lever may
travel clockwise bearing against the free corner 56 of the tripping
lever 46 to move the tripping lever counterclockwise against the
bias of the tripping plunger return spring 76. This in turn will
drive the slide member 52 to the left as viewed in FIG. 4 until it
reaches its tripping position and the mechanism assumes the
position shown in FIG. 6. In this connection it will be noted that
this positioning of the parts of the device is substantially the
same as during the resetting operation. Thereafter, release of the
reset button 22 will permit the slide member return spring 76 to
return the tripping plunger 54 to its retracted position in
substantially the same manner as it returns after a resetting
operation.
As can be seen from the foregoing detailed description the
undervoltage release device of the present invention advantageously
prevents resetting of the device while an undervoltage condition
persists or while the solenoid actuator is in a de-energized
condition. Additionally, the device requires a separate and
distinct resetting action not associated with the main ON/OFF
handle of the circuit breaker, requiring the operator of the
breaker to supply a said independent resetting force thereto. At
the same time the independent undervoltage tripping device of the
present invention prevents any attempt to defeat the undervoltage
release function of the unit. An added feature of the device is its
ability to permit the operator to trip the circuit breaker from an
ON or OFF position with the solenoid energized and further permits
an operator familiar with the device to detect a breaker trip
condition by means of the position of the reset button. Further, as
is evident from the drawing and description, all of these
advantages are achieved within a device that is compact, efficient,
simple and relatively trouble free.
As will be apparent to persons skilled in the art, various
modifications, adaptations and variations of the foregoing specific
disclosure can be made without departing from the teachings of the
present invention.
* * * * *