U.S. patent number 3,594,668 [Application Number 05/000,473] was granted by the patent office on 1971-07-20 for remote control circuit breaker.
This patent grant is currently assigned to Texas Instruments Incorporated. Invention is credited to David E. Clarke, William G. Foley.
United States Patent |
3,594,668 |
Clarke , et al. |
July 20, 1971 |
REMOTE CONTROL CIRCUIT BREAKER
Abstract
A miniature remote control circuit breaker in which a movable
contact member including a movable contact is engageable with a
fixed contact. Motor means, such as a solenoid and an armature
actuated thereby, move the contact member from a contacts-open
position to a contacts-closed position when the solenoid is
energized by remote switch means. Preferably a linkage including
two resiliently connected driving members is employed to couple the
motor means to the contact member. Condition-sensing (e.g.
current-sensing) latch means retain the contact member in its
contacts-closed position until the condition sensed varies beyond a
predetermined value whereupon the latch means releases the contact
member, thereby opening the contacts independently of the
energization of the motor means. Further latch means are provided
to retain the contact member in its closed position. The latter
latch means are responsive to further actuation of the remote
switch means thereby to release the contact member and separate
said contacts. A further solenoid and armature are preferably
provided to effect the release of the further latch means in
response to further actuation of the remote switch means.
Inventors: |
Clarke; David E. (Attleboro,
MA), Foley; William G. (Dorchester, MA) |
Assignee: |
Texas Instruments Incorporated
(Dallas, TX)
|
Family
ID: |
21691662 |
Appl.
No.: |
05/000,473 |
Filed: |
January 2, 1970 |
Current U.S.
Class: |
335/13;
335/38 |
Current CPC
Class: |
H01H
9/38 (20130101); H01H 71/40 (20130101); H01H
71/68 (20130101) |
Current International
Class: |
H01H
71/12 (20060101); H01H 9/30 (20060101); H01H
71/40 (20060101); H01H 71/10 (20060101); H01H
71/68 (20060101); H01H 9/38 (20060101); H01h
077/02 () |
Field of
Search: |
;335/13,38,43,15,19,73,174,177 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Claims
What we claim is:
1. A circuit breaker comprising:
a fixed contact;
a movable contact member including a movable contact adapted for
engagement with the fixed contact, said member being movable
between a first position in which said contacts are separated and a
second position in which said contacts are in conductive
engagement;
motor means and a linkage extending from said means to said contact
member for moving said contact member from its first position to
its second position when the motor means is actuated;
biasing means urging said contact member toward said first
position; and
condition-sensing latch means for retaining said contact member in
its second position until the condition sensed varies beyond a
predetermined value whereupon said latch means releases said
contact member to open said contacts independently of the actuation
of said motor means;
said linkage including a first driving member, an attachment
between said first driving member and the motor means, a second
driving member engageable with the movable contact member, a
resilient connection between said first and second driving members
to effect resilient engagement between the second driving member
and the contact member as the latter is driven to contact-closing
position and to effect lost motion between said driving members
after contact engagement.
2. A circuit breaker comprising:
a fixed contact;
a movable contact member including a movable contact adapted for
engagement with the fixed contact, said member being movable
between a first position in which said contacts are in conductive
engagement;
means comprising a solenoid and an armature, a linkage extending
from said armature to said contact member for moving said contact
member from its first position to its second position when the
solenoid is energized;
biasing means urging said contact member toward said first
position;
current-sensing latch means for retaining said contact member in
its second position until the current sensed exceeds a
predetermined value whereupon said latch means releases said
contact member to open said contacts independently of the
energization of said solenoid;
said linkage including a first driving member, an attachment
between said first driving member and the armature, a second
driving member engageable with the movable contact member, a
resilient connection between said first and second driving members
to effect resilient engagement between the second driving member
and the contact member as the latter is driven to contact-closing
position and to effect lost motion between said driving members
after contact engagement.
3. A circuit breaker according to claim 2 including further latch
means operative in connection with said first driving means for
retaining said contact member in its second position.
4. A circuit breaker according to claim 2 wherein said
current-sensing latch means comprises a catch, a finger extending
from said movable contact member and supported by said catch in
said second position, said engagement between the second driving
member and said movable contact member being in the form of a loose
rocking connection to permit rotary movement of the movable contact
member in movements between its various positions.
5. A circuit breaker according to claim 2 wherein said first
driving member is in the form of a first plate having a window from
opposite sides of which extend tongues for the reception of a
compression coil spring, and said second driving member is in the
form of a second plate slidable on one side of the first plate and
having a tongue portion within the coils of the spring and
shoulders engaging one of its ends.
6. A circuit breaker according to claim 5 which includes a third
plate on the opposite side of the first plate, said third plate
having a window for reception of the spring and from one side of
which extends a tongue portion within the coils of the spring to
hold it axially straight.
7. A circuit breaker according to claim 6 wherein said engagement
between the second driving member and said movable contact member
is in the form of a loose rocking connection to permit rotary
movement of the movable contact member in movement between its
various positions.
8. A circuit breaker according to claim 7 wherein the loose rocking
connection comprises a tongue on that end of the second driving
member which engages said contact member, and a slot in the contact
member into which said tongue projects.
9. A circuit breaker according to claim 2 which includes further
latch means operative in connection with said first driving means
for retaining said contact member in its second position, a second
solenoid and a second armature, switch means for energizing the
second solenoid, a second linkage connecting said second armature
with said second latch means to release it when the switch means is
actuated, said switch means being actuated upon movement of the
contact member to a third position in response to release of the
contact member by the current-sensing latch means.
10. A circuit breaker according to claim 9 including a fulcrum
engageable by the contact member to rotate it in moving from its
third to its first position so as to deactuate the switch
means.
11. A circuit breaker according to claim 9 which includes second
switch means for deenergizing the first said solenoid upon
actuation thereof, said second switch means being actuated by said
further latch means while it is retaining said contact member in
its second position.
12. A circuit breaker according to claim 2 in which the solenoid is
energizable by switch means remote from said circuit breaker.
13. A circuit breaker according to claim 9 in which said first and
second solenoids are alternatively energizable by switch means
remote from said circuit breaker respectively to move said contact
member into its second position and to release the further latch
means thereby to cause the contact member to move from its second
position to its first position.
14. A circuit breaker according to claim 13 which further includes
an indicator located with said remote switch means, said indicator
being energizable by the first said switch means upon actuation
thereof.
15. A circuit breaker according to claim 14 wherein said indicator
comprises a bimetal type thermal motor.
16. A circuit breaker according to claim 9 which further includes
manual means adapted to move said contact member to its second
position and alternatively to move said further latch means to
release said contact member from its second position and permit it
to return to its first position, said manual means having a lost
motion connection with said further latch means and a lost motion
connection with said contact member.
17. A circuit breaker according to claim 16, said manual means
having a neutral rest position in which it is not in engagement
with said contact member or said further latch means, said breaker
further including another switch means adapted to be actuated when
said manual means is moved from its neutral rest position thereby
to disconnect said remote switch means from the first said
solenoid.
18. A circuit breaker according to claim 9 which includes means for
ganging its further latch means to the further latch means of at
least one additional like breaker for multiphase operation whereby
the release of one of the further latch means releases all of said
ganged latch means.
Description
This invention relates to circuit breakers and more particularly to
remotely controlled circuit breakers.
With the advent of the larger jet aircraft and their increased
electrical power requirements, the weight and cost of the larger
loop runs of heavy expensive aviation cable between the power
generators and electrical loads via the flight engineer's console
or cockpit become excessive. A large portion of this cable expense
and weight can be eliminated by reducing the lengths of the power
lead runs. This can be effectively accomplished by the use of
remotely controlled circuit breakers located near the generator
with small remote control units positioned in the cockpit and
interconnected with the breaker itself by light inexpensive control
wires, thus permitting much shorter and direct power lead runs
between the generator gear and the loads. A typical jumbo jet may
require over 1000 circuit breakers, many of which advantageously
could be the remote control type. These remote control breakers
should not only function reliably to protect against overloads
(both of the short circuit and low level or ultimate trip types),
but should also function as contactors which are resettable and
trippable from the remote control unit. Existing remote control
circuit breakers, however, have various disadvantages. Some lack
any means for remotely indicating when the breaker has tripped due
to an overload, or fail to provide for both tripping as well as
resetting the breaker from the remote control unit, or do not
protect a load from both short circuit and ultimate trip or low
level overloads. Others do not have or fail to retain close
tolerances as to tripping levels, and are subject to other
difficulties. The remotely controlled circuit breakers of this
invention overcome these disadvantages and provide numerous
significant advantageous features.
Among the several objects of this invention may be noted the
provision of remotely controlled circuit breakers which permit
substantial economies in the reduction of cable weight and expense;
the provision of such breakers in which power switching, overload
sensing and the protection functions are provided in one unit
located in a position close to the power source and the load being
supplied and protected, while even smaller remote units are
positioned in the strategic and spatially limited area of the
cockpit or flight engineer's console, there to provide the control
or on-off signalling functions and to indicate overload conditions;
the provision of breakers of the type described which combine
contactor and breaker functions in one package, protect against all
types of overloads, and are inherently trip-free; the provision of
remote control circuit breakers which protect the circuits
regardless of the condition of the remote control unit and
circuitry and are independently fail-safe even in the event of
failure of control voltage; the provision of such breakers which
may be of the latch-in or nonlatch types and which comprise
substantially the same components with only minor modification; the
provision of circuit breakers which have and retain close
tolerances as to tripping levels and provide specific and
substantially constant contact pressure and calibration, which are
maintained throughout the life of the breaker; and the provision of
such remote control circuit breakers having minimal number of
control wires and which are compact, light in weight, reliable in
operation, will handle a wide variety of AC and DC voltage and
current requirements, and have a long operating life. Other objects
and features will be in part apparent and in part pointed out
hereinafter.
Briefly, a circuit breaker of this invention includes a fixed
contact and a movable contact member having a movable contact
engageable with the fixed contact and being movable between a first
or contacts-open position and a second or contacts-closed position.
Motor means are provided which have a linkage extending therefrom
to the contact member for moving said contact member from its first
position to its second position when the motor means is actuated.
Biasing means urge the contact member toward its first position. A
condition-sensing latch means retains the contact member in its
second position until the condition sensed varies beyond a
predetermined value whereupon the latch means releases said contact
member to open the contacts independently of the actuation of the
motor means. The linkage includes a first driving member, an
attachment between it and the motor means, a second driving member
engageable with the movable contact member, and a resilient
connection between said first and second driving members to effect
resilient engagement between the second driving member and the
contact member as the latter is driven to contact-closing position
and to effect lost motion between the driving members after contact
engagement.
The invention accordingly comprises the constructions hereinafter
described, the scope of the invention being indicated in the
following claims.
In the accompanying drawings, in which several of various possible
embodiments of the invention are illustrated,
FIGS. 1 and 2 are schematic and diagrammatic representations of two
remote control circuit breaker embodiments of the invention;
FIGS. 3--5 are elevations of the circuit breaker represented in
FIG. 1, parts being broken away, illustrating, respectively, the
components in a normal contacts-open, a normal contacts-closed and
a trip-free configuration or position,
FIG. 6 is an elevation of the circuit breaker represented in FIG.
2, parts being broken away;
FIG. 7 is a detail view of a contact member component taken
generally on line 7-7 of FIG. 3 with parts broken away;
FIG. 8 is a detail view of a latch member component taken generally
on line 8-8 of FIG. 3 with parts broken away;
FIG. 9 is an elevation of another breaker embodiment of this
invention including a manually operable arrangement to move the
breaker contact member between its closed and open positions;
FIGS. 10A--C are elevations of three component slider plates of a
slider assembly of a circuit breaker of this invention; and
FIGS. 11A and B are edge elevations of the slider assembly in its
two positions.
Corresponding reference characters indicate corresponding parts
throughout the several views of the drawings.
Referring now to the drawings, and more particularly to FIG. 1, a
remote control unit, indicated generally at RC1, is shown connected
by a single conductor 1 to a circuit breaker CB1. Remote control
RC1 includes a circuit breaker device 3 of the bimetal thermostatic
type including an auxiliary set of contacts 5 commonly operated by
a pushbutton PB1. Upon actuation of PB1 to the left as shown in
FIG. 1, the main contacts of device 3 are bridged by the breaker's
bimetallic element 7 and auxiliary contacts 5 are opened. A load
control switch S1 is optionally provided to connect conductor 1 to
the positive side of a control voltage source represented as +V
(the negative side of which is grounded) via bimetallic element 7
when pushbutton PB1 is actuated to open contacts 5 and element 7 is
bridging the main contacts of breaker 3. Control switch S1, when
actuated or moved to its alternate position, grounds conductor
1.
Breaker 3 may be any conventional bimetal type breaker preferably
having a low current rating, e.g., on the order of one-half amp.
When its rated current-carrying capacity is exceeded, its bimetal
element 7 will reverse its curvature and cause pushbutton PB1 to
pop outwardly (to the right as shown in FIG. 1) thus serving to
indicate, as will be described hereinafter, when main breaker CB1
is tripped because of an overload. It will be understood that other
conductor means, such as an electromagnetic type or a light, may be
used to provide an indication at the remote control unit RC1 of
overload tripping of CB1.
Breaker CB1 includes two terminals T1 and T2 which are connected in
series with a power lead or conductor interconnecting a source of
electric power to an electrical load. The current path from T1 to
T2 includes a current-sensing latch means LM1 having an
electromagnet 9 and a U-shaped bimetal element 11, a flexible braid
lead 13 and a contact member 15 carrying a movable main contact 17
and a movable arcing contact 19 which respectively conductively
engage a fixed main contact 21 and a fixed arcing contact 23. Latch
means LM1 also includes a pivotable latch member 25 pivoted about a
pin 27 and having an abutment or catch 29 and an upper end 31
adapted to be contacted and moved to the right by the upper end of
bimetal element 11 when the latter is heated by current exceeding
the breaker's rating. Contact member 15 has an end 33 supported on
catch 29 which constitutes a pivot for contact member 15 when the
latter is actuated by a linkage 35 to move the fixed and movable
contacts thereof into conductive engagement. Contact member 15 is
urged or biased toward its contacts-open position by a spring as
represented at 37. Linkage 35 is actuatable by an armature 39 of a
reset solenoid RS. Coacting with linkage 35 is a further latch
means LM2 which, when linkage 35 is actuated to move contact member
15 to its closed position, will engage linkage 35 and retain
contact member 15 in its contacts-closed condition. A spring
represented at 41 biases a latch arm 43 of LM2 against the linkage
for retention thereof. Latch arm 43 is actuatable by a trip
solenoid TS which when energized retracts arm 43 to release the
linkage 35 and permit the contact member to return to its
contacts-open position.
When PB1 is in its closed position with bimetal element 7 bridging
the main contacts of breaker 3 and switch S1 is in the position
illustrated, a circuit energizing reset solenoid RS is completed
through one set of contacts of a double-throw single-pole mode or
latch switch LS, thereby driving contact member 15 downwardly into
its closed position through linkage 35. This action moves switch LS
to its other mode wherein it connects solenoid TS to conductor 1
which is at potential +V. As the other terminal of TS is also
connected to +V, it will remain deenergized until further actuation
of the breaker 3 or switch S1. If a fault or overload condition
occurs, the overcurrent condition will cause latch member 25 of
latch means LM1 to pivot clockwise and release the end 33 of
contact member 15, thus permitting the contacts to open under the
bias of spring 37. As contact member end 33 moves clockwise it
actuates a trip or overload switch OS, causing it to close and
ground conductor 1 through an optional resistor 45. The current
then drawn through bimetal 7 will cause it to heat and pop open,
actuating PB1 to indicate at the remote control unit RC1 that an
overload condition has tripped breaker CB1. Tripping of remote
control RC1 energizes trip solenoid TS which disengages arm 43 of
LM2 to release the linkage 35 and permit the contact member to
return to its contacts-open position.
Breaker CB1 may be operated as a contactor from RC1 by either
moving load control switch S1 to its opposite position or manually
moving PB1 to the position illustrated in FIG. 1, thereby to trip
breaker CB1 from a remote position. Either action connects
conductor 1 to ground and as the other terminal of trip solenoid TS
is connected to +V, TS is energized via the contacts of latch
switch LS thereby firing or energizing TS to release latch means
LM2 and permit contact member 15 to move to its contacts-open
position. In this mode of operation the current-sensing thermally
responsive latch means LM1 are not actuated and the end 33 of
contact member 15 pivots on abutment 29. Thus the overload switch
OS is not actuated in this contactor-trip mode of actuation.
Resetting of breaker CB1 after tripping is accomplished by
actuation of the remote unit RC1 as described above, so as to
energize or fire reset solenoid RS. If tripping is due to an
overload, CB1 will be trip-free, i.e., as long as bimetal element
11 remains hot, latch member 25 will be moved to the right and
contact member end 33 will have no available point on which to
pivot.
If loss of control power or an open circuit occurs on the control
line, contact member 15 of breaker CB1 will not change its position
since neither the trip nor reset solenoids TS and RS can then be
energized. Also, if control conductor 1 is grounded when the
contact member 15 of breaker CB1 is in its open position, both
terminals of solenoid RS are at ground potential and it will not
fire, so that CB1 cannot be reset under this condition. If control
member 15 is closed and conductor 1 becomes grounded, trip solenoid
TS will be fired, opening breaker CB1 and PB1 will be actuated by
bimetal element 7.
It is to be noted that load control switch S1 is optionally
provided to minimize wear on breaker 3. If the latter is used not
only for resetting after overload trips but also for all operations
in the contactor mode, this breaker would have to have a useful
life of many tens of thousands of operating cycles. By using S1 in
this contactor mode of operation and building breaker 3 to last
several thousands of cycles, switch S1 can be more economically
designed to have a reliable life of many tens of thousands of
operational cycles, and provide a remote control unit with
increased overall reliability and operating life but at a decreased
cost.
The FIG. 1 remote control circuit breaker system is of the latch-in
type, i.e., during normal operation the contact member 15 is
latched in its contacts-closed position with reset solenoid RS
being deenergized. One or the other of latch means LM1 or LM2 must
be actuated to open the contacts, the latter by energization of
trip solenoid TS to overcome the latching bias of spring 41. In
such a latch-in system, failure of the control power or
interruption thereof will not trip breaker CB1. In some instances
it is desirable to provide a nonlatch type operation, i.e., the
contact arm or member is held closed by a latch means which is
maintained energized so that upon any interruption of control power
the breaker automatically opens and must be reset to reclose. This
type operation is conveniently accomplished in accordance with this
invention with only minor modification of a few components of
breaker CB1 and unit RC1. A nonlatch system is illustrated in FIG.
2, by utilizing a remote control unit RC2 which employs a breaker
3' (which is identical to breaker 3 but includes no auxiliary
contacts) and a single-pole single-throw load control switch S1'
rather than a double-throw switch S1. A circuit breaker CB2 is
utilized instead of breaker CB1, the former having a single-pole
single-throw latch switch LS' and modified latch means LM2', trip
solenoid TS' and biasing spring 41'. To close or reset contact
member 15, load control switch S1' or breaker 3' is operated to
apply +V control voltage to reset solenoid RS. However, in this
nonlatch system of FIG. 2, the trip solenoid TS' is concurrently
energized to urge latch arm 43' into engagement with linkage 35 so
as to maintain it in its closed position when it reaches that
position. As latch arm 43' is lightly biased out of latching
engagement by a spring 41', any loss or interruption of control
power will cause latch means LM2' to release linkage 35 and open
the contacts. Operation of this nonlatch system of FIG. 2 upon
overload is essentially the same as described above in regard to
the latch-in system of FIG. 1. That is, overload switch OS is
actuated momentarily by contact member 15 moving into its trip-free
position as abutment 29 is moved out from under end 33 of contact
member 15 thereby applying the control voltage across bimetal
element 7 and resistor 45, the controlled short circuit constituted
thereby causing a relatively high current flow therethrough, thus
causing breaker 3' to operate and indicating at remote control unit
RC2 that breaker CB2 has tripped due to an overload. The opening of
breaker 3' opens the circuit through bimetal element 7 and the
automatic release of linkage 35 by latch means LM2' permits load or
mode transfer switch LS' to reclose thus preparing the reset and
trip solenoids for subsequent refiring to reset breaker CB2.
It is to be noted that in both the latch-in and nonlatch systems of
FIGS. 1 and 2, latch means LM1 operates to cause contact member 15
to move to an open position while linkage 35 remains in its latched
or actuated position. Thus, the circuit-productive function of CB1
and CB2 is maintained independently of loss of control power or
malfunctions on the control line. Any load fault will cause latch
means LM1 to trip breaker CB1 or CB2 and clear the fault.
Referring now more particularly to FIGS. 3--5, the detailed
structure of an exemplary circuit breaker CB1 is illustrated in its
respective three modes or conditions, viz., open, closed and
trip-free. Breaker CB1 is assembled in a housing H molded of
suitable plastic or synthetic resin-insulating material with
appropriate recesses and the like for retaining and mounting
components of the breaker mechanism described hereinafter. Terminal
T1 is formed integrally with a base portion 45 having a zigzag
extension 47 and an upper portion 49 on which is mounted U-shaped
bimetal element 11. Projecting through openings in extension 47 are
a pair of insulated poles 51 which, together with the conductive
turn or turns constituted by the zigzag configuration of 47,
comprise an electromagnet which includes in its magnetic circuit
the pivoted latch member 25. Latch member 25 includes an arm
portion 53 which is preferably constructed of a bimetal laminate to
provide ambient temperature compensation. The distal end 31 of arm
53 is adapted to be engaged by an extension 55 of bimetal element
11. An eye 57 is provided in the top of latch member 25 for
attachment of one end of a spring 59, the other end of which is
anchored to a pin 61 mounted in the body of housing H. Spring 59
exerts a biasing action on latch member 25, tending to hold it in
the position shown and resisting pivoting action around pivot pin
27, also journaled or mounted in housing H. Thus abutment or catch
29 is normally held in a position adapted to be engaged by a finger
63 secured at end 33 of contact member 15. Braid 13 flexibly
electrically interconnects the free end of bimetal element 11 to
contact member 15 at 65. Contact member 15 includes a main arm
portion 15a to which is secured the movable main contact 17 and
rather flexible resilient auxiliary arm portion 15b carrying
movable arcing contact 19. Portion 15b is slotted to provide an
opening 67 through which main contact 17 projects. Secured by
welding or the like to a base 69 integrally formed with terminal T2
is a stepped contact assembly, the higher portion constituting the
fixed or stationary contact 21, the lower portion being the fixed
arcing contact 23. Auxiliary branch or arm 15b flexes, as
illustrated in FIG. 4, to permit firm conductive engagement between
mating pairs of main and arcing contacts, the latter leading the
former as member 15 moves into its closed-contact position (FIG. 4)
and trailing it as member 15 moves back to its open-contact
position (FIG. 3). This action protects the main contacts from the
arcing action, concentrating this at the arcing contacts to insure
that good electrical conductivity will be maintained between
contact member 15 and terminal T2 which is secured to housing
H.
Contact member 15 includes a C-shaped bracket 15c having a cross
slot 71 in its upper reach and an eye 73 in its forward reach. One
end of spring 37 is attached to bracket 15c at eye 73 and the other
end of spring 37 is anchored to a pin 75 mounted in housing H, thus
biasing contact member 15 to move clockwise. Bracket 15c has an
opening 76 at the knee juncture of the upper and front reaches
thereof so as to provide for unobstructed passage and movement of
spring 37. Linkage 35, which comprises a slider assembly including
three slider plates 35a, 35b, 35c and a coil compression spring
35d, extends from an armature end 77 of reset solenoid RS to engage
contact member 15 by a loose rocking and resilient connection.
Slider plate 35b of linkage or slider assembly 35 has an extension
79 (FIG. 10B) at its upper end with a T-slot 81 for coupling
engagement with the enlarged end 77 of the armature. Coil
compression spring 35d is nested within a window 83 having opposed
tongues 85 projecting from the top and bottom thereof. A laterally
extending actuation tab 87 projects from one edge of slider plate
35b.
Slider plate 35a (FIG. 10A) has an upwardly extending tongue 89
which, when slider plates 35a and 35b are assembled as shown in
FIGS. 11A and 11B, is positioned within the coils of spring 35d,
the lower end of this spring engaging shoulders 88. A tongue 91
projects downwardly from the lower end of plate 35a for engagement
within slot 71 of contact member 15. Four bosses 93 are formed in
the surface of plate 35a and provide a reduced friction engagement
with the opposing surface of plate 35b when assembled. The third
slider plate 35c (FIG. 10C) has a tongue 95 formed at the top of a
window or slot 97. This tongue extends downwardly so as to be
positioned within the coils of spring 35d when the plates are
assembled and thus serve as a spring retainer. When reset solenoid
RS is energized, the downward thrust of armature end 77 is
transmitted through the first driving member (slider 35b) which is
resiliently coupled (by spring 35d) to the second driving member
(slider plate 35a) to drive contact member 15 downwardly. The
closing impact of the contacts is cushioned by spring 35d which
maintains substantially constant contact pressure even though the
contacts may wear down from extended usage. As contact member 15 is
thus moved from its open position (FIG. 3) to its closed position
(FIG. 4) against the bias of spring 37, finger 63 of contact arm
end 33 is seated against abutment or latch catch 29. Sliders 35a
and 35b are provided with respective elongate slots 99 and 101
which, when these sliders are assembled with slider plate 35c,
register with the latter's slot 97 and thus provide an elongate
opening for passage of contact arm spring 37. Slide assembly 35
moves within a pair of opposed guideways 102 and 102' formed on the
inner surfaces of the sidewalls of housing H.
When the linkage constituted by slider assembly 35 has moved arm 15
into its closed position of FIG. 4, latch means LM2 engages to hold
slider plate 35b in its downward position. Latch means LM2 includes
a bellcrank lever having an upper arm 103 with a latch hook 105 at
its end for engaging the top edge of slider plate 35b, and a second
arm 107 from which extends a lateral arm 109 carrying a spring
finger 111. Latch means LM2 is biased clockwise by spring 41 about
a latch pivot pin 113, thereby urging latch hook 105 into
engagement with the top edge of slider plate 35b. Latch means LM2
is moved from its latched (FIG. 4) to its unlatched (FIG. 3)
position by firing or energizing trip solenoid TS, which has an
armature 115 coupled to latch arm 107 by a connecting link 117.
Energizing solenoid TS moves latch means LM2 counterclockwise about
its pivot 113 against the bias of spring 41 and thereby releases
linkage 35, permitting arm 15 to move clockwise about its pivot
point on catch 29 and under the contact opening bias of spring 37.
Latch arm 107 includes an aperture 119 adapted to receive a ganging
bar for cross coupling adjacent breaker units CB1 for multiphase
operation so that tripping of one breaker CB1 in one phase will
trip all of the ganged breakers.
It will be noted that spring finger 111 will depress and thus
actuate latch switch LS, shown in phantom when latch means LM2
engages the top edge of slider plate 35b upon the contact member 15
reaching its closed position. Thus switch LS remains in its FIG. 4
actuated position as long as contact member 15 is closed and until
the trip solenoid TS is fired.
Under an overload condition, breaker CB1 is tripped by latch means
LM1 independently of latch means LM2. If the overload is due to a
short circuit on an extremely heavy current drawing fault, the
electromagnet constituted by poles 51 and the turns formed by
extension 47 will immediately pull in latch member 25, moving
abutment or catch 29 to the right and causing contact member 15 to
move to its tripped position (FIG. 5). A relatively low level
longer term fault will cause bimetal element 11 to heat and move
its extension 55 to the right, thus actuating latch member 25
similarly to release end 33 of contact member 15. As member 15
moves clockwise under the bias of spring 37, it pivots about tongue
91 so that the upper surface of the free end of main contact arm
portion 15a moves against the actuator button of overload switch OS
and depresses it. As discussed above, actuation of switch OS, shown
in phantom, energizes or fires trip solenoid TS, thereby releasing
latch means LM2 and allowing slider assembly 35 to move to its FIG.
3 position. As slider assembly 35 moves upwardly, opening to the
FIG. 11A expanded position because of compression spring 35d,
contact member 15 will pivot first around the actuator button of
switch OS as spring 37 exerts an upward force on bracket 15c. After
initial counterclockwise rotation of contact member 15 around this
pivot point, the upper intermediate surface of main contact arm
portion 15a will strike a pin 121 mounted in housing H. The pivot
point then shifts to pin 121, which serves as a fulcrum as contact
member 15 moves to its FIG. 3 position with its free end separated
from switch OS and with its end finger 63 poised over catch 29 when
the latter returns to its normal cool position. Thus overload
switch OS is only momentarily actuated upon overload tripping by
release of latch LM2. This momentary actuation, however, fires trip
solenoid TS, which releases latch LM1 and also completes a
relatively high current circuit through bimetal 7 of remote unit
RC1 so that pushbutton PB1 will pop out to signal tripping of CB1
due to an overload. The fault is thereby cleared and both remote
unit RC1 and breaker CB1 are prepared for reclosing or resetting
when the current-sensing thermally responsive latch means LM1 has
cooled and returned to its normal position.
Breaker CB1 may be calibrated by adjustment of screw 123 which
moves the end of bimetal extension 55 relative to end 33 of arm 53
of latch member 25. Once the breaker is calibrated as desired, this
calibration will be accurately maintained over the long operational
life of the breaker because of the provision of various features of
this invention. These features include the unique slider linkage
assembly 35, the engagement arrangement between tongue 91 in slot
71 and the method of biasing contact member 15 by spring 37 against
latch member 25. Maintenance of close tolerance calibration is a
function of a number of variables, all of which are taken into
account in this breaker structure. The moment arm from the pivot
point of finger 63 on catch 29 to the point of engagement of
linkage 35 with the contact member 15 is one such variable. This is
maintained constant as spring 37 urges contact member 15 to the
right so that the tip of finger 63 will always be snugly moved into
abutting contact with the left surface of member 25 and fully
engage the top surface of catch 29. Thus catch 29 will always have
the same frictional factor to overcome when it moves to a release
position and the spacing or moment arm between that point and the
point of engagement of tongue 91 and contact member 15 will be
maintained constant. Therefore, even with the loose rocking
engagement between the latter two components, which can be
inexpensive stampings, precise calibration and very close
tolerances can be attained as contact member 15 is biased by spring
37 consistently to return to this precise reference position,
regardless of wear. Spring 37 also exerts a substantially constant
force biasing the slider plates 35a, 35b and 35c together. Further,
as discussed above, compression spring 35d maintains constant
contact force despite possible contact erosion and the resultant
changes in the angularity of contact member 15 when closed.
A nonlatch type breaker CB2 as described above in regard to FIG. 2
is further illustrated in FIG. 6. Such a breaker may be made from
substantially the same components as those used to fabricate
breaker CB1 and with only minor modifications. These involve
changing the shape of latch hook 105 to that of latch hook 105'
wherein the engaging face of hook 105' is angled slightly upwardly,
and inverting solenoid TS so that it will pull its armature 115
inwardly upon energization rather than thrusting it outwardly. As
the trip solenoid is inverted and the wiring of the latch switch is
slightly modified in the CB2 breaker, these components are
indicated at TS' and LS', the reference character LM2' being used
to indicate the modified nature of this latch means. Another
modification involves elimination of spring 41 and the stiffening
of spring 111 of the CB2 breaker, as indicated at 111'. This
provides a modest bias from the inherent biasing force of the
internal spring in the microswitch type latch switch LS', which
urges this latch LM2' into a released or unlatched position. As
noted above, the trip solenoid is maintained energized continuously
while breaker contact member 15 remains closed and will only be
deenergized upon intermittent actuation of overload switch OS
during tripping due to overload or by operation in the contactor
mode by remote unit RC2. Only a low level energization current
through trip solenoid TS' is required to maintain slider assembly
35 latched.
In certain instances it may be desirable to provide for local
manual actuation of the circuit breaker CB1 and FIG. 9 illustrates
an exemplary embodiment including this feature. A spring-loaded
pushbutton PB3 of insulating material is slidably mounted on
housing H and coupled to a cam plate 125 by a connecting link 127.
Another microswitch S2 similar to latch switch LS and overload
switch OS is mounted on housing H and has an actuator arm 129, the
end of which bears against the periphery of cam plate 125 in the
neutral or rest position of this plate (shown in solid lines) and
is biased so as to nest in a notch 131 of this plate by the
internal biasing force of microswitch 52 and the spring action of
the flexible actuator arm 129. Switch S2 is connected in the
circuitry for reset and trip solenoids RS and TS. Thus, when cam
plate 125 is moved in either direction around its pivot 133 from
its solid-line rest position, actuator arm 129 is moved to the
position indicated to its broken line position to actuate switch S2
and effectively disconnect or disable both solenoids so that
neither can be actuated from the remote unit RC1.
To manually locally reset or reclose breaker CB1, pushbutton PB3 is
pressed (upwardly as shown in FIG. 9) and tab 87 of slider plate
35b is moved by an edge of cam plate 125 from its solid line to its
double-dot-dash-line position, thus manually closing the contacts
of breaker CB1 (FIG. 4). As latch means LM2 is biased to an engaged
latching position by spring 41, its arms 107 and 109 will move from
their solid- to their double-dot-dash-line positions as shown and
pushbutton PB3, when released, will return to its neutral rest
position under the centering bias of its captive spring 137.
To manually trip breaker CB1, pushbutton PB3 is pulled down (as
viewed in FIG. 9) so that cam plate finger 135 will contact and
move latch arm 109 to its solid-line position and thus disengage
latch means LM2 and permit slider assembly linkage 35 to release
and open the breaker contacts, as represented by actuator tab 87
moving to its solid-line position. Thus in manual local actuation
to either a contacts-open or a closed-contact position, there is a
lost motion connection between PB3 and the operating components of
breaker CB1, and when cam plate 125 is moved in either direction
from its neutral rest solid-line position, switch S2 will be
actuated to deenergize these solenoids to prevent any inadvertent
override by concurrent actuation of remote control unit RC1.
If it should be desired to provide remote indication of the
physical position of contact member 15, this is provided by a
further switch S3 secured to housing H and having an actuator arm
139 which engages slider assembly actuator tab 87. In an
open-contact position, tab 87 will be in its solid-line position
and switch S3 will not be actuated, but when contact member 15 is
moved to its closed position, tab 87 will move down to its
double-dot-dash position and actuator switch S3 which will close a
circuit to a remote indicator to signal that the breaker contacts
are physically closed.
It is to be understood that remote control circuitry other than
that specifically illustrated herein may be utilized for remote
control of the breakers of this invention. It is also to be noted
that latch means other than LM1 (such as one uncompensated for
ambient temperature variations), LM2 and LM2' are useful in the
practice of this invention.
In view of the above, it will be seen that the several objects of
the invention are achieved and other advantageous results
attained.
As various changes could be made in the above constructions without
departing from the scope of the invention, it is intended that all
matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
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