U.S. patent number 3,783,423 [Application Number 05/327,964] was granted by the patent office on 1974-01-01 for circuit breaker with improved flux transfer magnetic actuator.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to Alfred E. Mater, John A. Wafer.
United States Patent |
3,783,423 |
Mater , et al. |
January 1, 1974 |
CIRCUIT BREAKER WITH IMPROVED FLUX TRANSFER MAGNETIC ACTUATOR
Abstract
A circuit breaker comprises a magnetic trip actuator comprising
an armature movably supported on a stationary non-magnetic support
pin, and permanent magnet means supplying magnetic flux that
operates through a magnetic supporting frame to maintain the
armature in an initial position. When released, the armature moves
in an opening in the frame to actuate the breaker mechanism to trip
the breaker. Upon movement of an operating handle structure to a
reset position to reset the mechanism of the circuit breaker, the
handle structure engages a pivoted reset member to move the reset
member against the armature to thereby reset the armature in the
initial position.
Inventors: |
Mater; Alfred E. (Beaver Falls,
PA), Wafer; John A. (Monroeville, PA) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
|
Family
ID: |
23278876 |
Appl.
No.: |
05/327,964 |
Filed: |
January 30, 1973 |
Current U.S.
Class: |
335/174; 335/229;
335/262 |
Current CPC
Class: |
H01H
71/322 (20130101) |
Current International
Class: |
H01H
71/32 (20060101); H01H 71/12 (20060101); H01h
009/20 () |
Field of
Search: |
;335/174,177,179,229,230,234,262 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: A. T. Stratton et al.
Claims
We claim:
1. A circuit breaker comprising a pair of contacts, a trip
actuator, said trip actuator comprising a frame of magnetic
material, said frame having an opening therein, a non-magnetic
support pin supported in said frame, a tubular shaped magnetic
armature supported for movement on said stationary support pin in
proximity to said opening, permanent magnet means supported in said
frame and supplying magnetic flux that operates in a first magnetic
circuit through said support frame and said armature to maintain
said armature in an initial position, spring means biasing said
armature toward an actuating position, coil means energizable to
affect said magnetic flux to thereby effect release of said
armature, and upon release of said armature said spring means
moving said armature on said stationary support pin through said
opening to a tripping position to effect opening of said
contacts.
2. A circuit breaker according to claim 1, said magnetic frame
comprising a magnetic generally U-shaped part and a magnetic base
part extending across the legs of said magnetic generally U-shaped
part, said first magnetic circuit extending through said permanent
magnet means in said generally U-shaped magnetic part, and upon
movement of said armature to said tripping position said permanent
magnet means supplying magnetic flux that operates in a second
magnetic circuit through the leg portions of said generally
U-shaped part said magnetic base plate and said armature.
3. A circuit breaker according to claim 1, said magnetic frame
comprising a generally U-shaped magnetic part comprising a pair of
opposite legs and a bight portion between said opposite legs, said
magnetic frame comprising a magnetic base plate part extending
across said opposite legs in proximity to the free ends of said
opposite legs, a magnetic pole piece on said support pin between
said armature and said bight portion, said opening in said frame
being in said magnetic base plate part, said coil being disposed
between the legs of said magnetic U-shaped part over said pole
piece, said permanent magnet piece comprising a pair of magnet
members each of which magnet members is disposed adjacent a
different leg of U-shaped part with said magnet members being
disposed on opposite sides of said armature, said permanent magnet
members supplying magnetic flux that operates in said first
magnetic circuit through said opposite legs of said U-shaped part,
said bight part, said pole piece means and said armature to
maintain said armature in said initial position against the bias of
said spring means, upon energization of said coil magnetic flux
being transferred to a second magnetic circuit through said
permanent magnet members, said opposite of said U-shaped part said
magnetic base plate part and said armature whereupon said spring
means moves said armature through said opening to said second
position to effect opening of said contacts.
4. A circuit breaker according to claim 1, said circuit breaker
comprising an insulating housing having an opening therein, an
operating handle extending through said opening and being manually
operable to open and close said contacts, upon the occurrence of a
tripping operation said operating handle being movable to a reset
position to reset said circuit breaker, and upon movement of said
handle to said reset position said handle structure operating to
move said armature back to said initial position.
5. A circuit breaker according to claim 4, an intermediate reset
member pivotally supported in proximity to said armature, said
operating handle upon movement to said reset position pivoting said
reset member whereupon said reset member operates against said
armature to move said armature to said initial position.
6. A circuit breaker according to claim 3, said circuit breaker
comprising an insulating housing having an opening therein, an
operating handle extending through said opening and being manually
operable to open and close said contacts, upon the occurrence of a
tripping operation said operating handle being movable to a reset
position to reset said circuit breaker, and upon movement of said
handle to said reset position said handle structure operating to
move said armature back to said initial position.
7. A circuit breaker according to claim 6, an intermediate reset
member pivotally supported in proximity to said armature, said
operating handle upon movement to said reset position pivoting said
reset member whereupon said reset member operates against said
armature to move said armature to said initial position.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
The hereindisclosed circuit breaker is more specifically disclosed
and described in the copending applications of Alfred D. Maier Ser.
No. 327,961, filed Jan. 30, 1973; Alfred E. Maier et al Ser. No.
327,964, filed Jan 30, 1973. and Alan B. Shimp Ser. No. 327,973,
filed Jan. 30, 1973.
BACKGROUND OF THE INVENTION
1. Field of the Invention:
Circuit breakers of the type comprising a releasable mechanism
releasable to trip the breaker and a flux transfer magnetic trip
actuator operable to effect release of the releasable
mechanism.
2. Description of the Prior Art
In the patents of Kuhn, U.S. Pat. No. 3,544,932 issued Dec. 1,
1970; to Patel, U.S. Pat. No. 3,544,931 issued Dec. 1, 1970; and to
Wagner, U.S. Pat. No. 3,530,414 issued Sept. 22, 1970, there are
disclosed circuit breakers having flux transfer magnetic trip
actuators of the type comprising an armature structure releasable
to trip the breaker and permanent-magnet means operating to
maintain the armature structure in an initial non-tripping
position.
SUMMARY OF THE INVENTION
A circuit breaker comprises cooperable contacts, a releasable
mechanism releaseable to effect a tripping operation automatically
opening the contacts and a flux transfer magnetic trip actuator
operable to release the mechanism. The trip actuator comprises a
frame of magnetic material having an opening therein, a
non-magnetic support pin supported in the frame and a tubular
shaped magnetic armature supported on the support pin in an initial
position. Spring means biases the armature toward an actuating or
tripping position. Permanent magnet means supported in the frame
supplies magnetic flux that operates in a first magnetic circuit
through the frame and armature to maintain the armature in the
initial position. Coil means supported in the frame is energizable
to affect the magnetic flux to thereby effect release of the
armature whereupon the spring means moves the armature through the
opening in the frame to the tripping position to release the
mechanism to thereby affect opening of the contacts. During
resetting operations of the mechanism, when the circuit breaker
handle structure is moved to a resetting position, the handle
structure engages a pivoted reset member to move the reset member
against the armature structure to thereby reset the armature
structure in the initial position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side sectional view, with parts broken away, of the
center pole unit of a three-pole circuit breaker constructed in
accordance with the principles of this invention;
FIG. 2 is an end view, with parts broken away, of the flux transfer
magnetic trip actuator seen in FIG. 1;
FIG. 3 is a sectional view taken generally along the line III--III
of FIG. 2; and
FIG. 4 is a sectional view taken along the line IV--IV of FIG. 3
with the armature shown in the actuated or tripping position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, there is shown in FIG. 1 the center pole
unit of a three-pole molded-case type circuit breaker 5. The
circuit breaker mechanism is more specifically described in the
above-mentioned patent applications Ser. No. 327,961 and Ser. No.
327,964. Thus, only a brief description of the circuit breaker
mechanism is provided herein. The circuit breaker 5 comprises an
insulating housing 7 and suitable barrier means that separates the
housing into three adjacent insulating compartments for housing the
three pole units of the three-pole circuit breaker in a well-known
manner. In the closed position of the circuit breaker, a circuit
through each pole unit extends from a terminal 9 through a
conductor 11, a conductor 13, a movable contact structure indicated
generally at 15, a conductor 17, to another terminal 19. Contacts
21, 23 and 25 on the movable contact structure 15 cooperate with
stationary contacts 27, 28 and 29 to bridge the conductors 13, 17
in the closed position of the movable contact structure 15. A
flexible conductor 31 electrically connects the conductor 13 and a
movable contact arm 33, that supports the arcing contacts 25.
During opening operations of the movable contact structure 15, the
arcing contact 25 separates from the stationary arcing contact 29
last to draw arcs in an arc-extinguishing structure indicated
generally at 35. The movable contact structure 15 is supported on a
contact carrier 37 that is supported for pivotal movement on a pin
39. A lower toggle link 41 is pivotally connected to the contact
carrier 37 at the lower end thereof by means of a pivot pin 43. The
lower toggle link 41 is pivotally connected to an upper toggle link
45 by means of a knee pivot pin 47. A pair of over center tension
springs 49 are connected at the lower ends thereof to the knee
pivot 47 of the toggle and at the upper ends thereof to the bight
portion of an operating lever 51. The operating lever 51 is an
inverted generally U-shaped lever that is supported on the inner
ends of the legs thereof for pivotal movement about a pair of pins
53. The upper toggle link 45 is pivotally connected to a
releaseable member 55 by means of a pivot pin 57. The releaseable
member 55 is supported for pivotal movement at one end thereof on a
pin 59 and is latched at the other end thereof by means of a latch
structure indicated generally at 61. A handle structure indicated
generally at 63 is connected to the upper end of the operating
lever 51 and comprises a handle part 65 that protrudes through an
opening 67 in the front of the housing 7 to permit manual operation
of the circuit breaker. The handle structure 63 also comprises a
shroud part 71 that substantially closes the opening 67 in all
positions of the handle structure 63.
The circuit breaker is shown in FIG. 1 in the open position with
the releasable trip member 55 latched in the latched position by
means of the latch structure 61. In order to close the circuit
breaker, the handle 65 is moved in a clockwise direction from the
"off" position to an "on" position to move the operating lever 51
clockwise about the pivot 53. During this movement, the springs 47
are moved overcenter to erect the toggle 41, 45 to thereby pivot
the movable contact carrier 37 of the center pole unit in a
clockwise direction about the pivot pin 39 to move the movable
contact structure 15 into the closed position. Since all of the
contact carriers 37 of the three pole units are connected for
simultaneous movement by means of a rigid insulating tie bar 75,
this movement simulatenously closes the contact structures of all
three pole units. In order to manually open the circuit breaker,
the handle structure 63 is moved counterclockwise to the off
position seen in FIG. 1. This moves the springs 49 overcenter to
cause collapse of the toggle 41, 45 to thereby pivot the three
contact carriers 37 about the pivot pins 39 in a counterclockwise
direction to the open position shown in FIG. 1.
The free end of the releasable member 55 is engaged under a roller
member 79 that is mounted on a first latch member 81 that is
pivotally supported on a fixed pivot pin 83. A second latch member
85, that is supported for pivotal movement on a pair of spaced pins
87 (only one of which is seen in FIG. 1) comprises a pair of arms
that engage a pair of second rollers 89 that are supported on the
first latch member 81 to latch the first latch member 81. A third
latch member 93 is supported for pivotal movement about an axis
that extends normal to the plane of the paper as seen in FIG. 1 and
that is indicated at 95. The latch member 81 comprises a window
opening that receives a projection on the second latch member 85 to
latch the second latch member 85 in the latched position seen in
FIG. 1.
An improved flux transfer magnetic trip actuator indicated
generally at 99 is provided to effect tripping operations of the
circuit breaker, in a manner to be hereinafter described, upon the
occurrence of an overload current in any of the three pole units of
the circuit breaker. The magnetic trip actuator 99 comprises an
armature 101 (FIGS. 2-4) that comprises a projection 103 and a
shoulder 105. When the armature 101 is released, in a manner to be
hereinafter described, a spring 107 moves the armature from the
initial position seen in FIG. 3 to the actuated or tripping
position seen in FIG. 4. During this movement, the projection 103
moves through an opening in the third latch member 93 (FIG. 1) and
the shoulder portion 105 engages the third latch member 93 to pivot
the third latch member 93 in a counterclockwise direction about the
axis 95 thereof. With the circuit breaker in the closed position
and the toggle 41, 45 in the erected position the springs 49 are in
a charged condition, and movement of the latch member 93 to the
unlatching position will release the latch structure 61 to release
the releasable member 55 whereupon the charged springs 49 will
collapse the toggle 41, 45 to trip the breaker. Upon movement of
the third latch member 93 to the unlatched position the second
latch member 85 and first latch member 81 will be free to move to
an unlatched position. The charged springs 49, operating against
the releasable member 55 biasing the releasable member 55 in a
clockwise direction about the pivot 59, will force the releasable
member 55 clockwise to force the first latch member 81
counterclockwise to force the second latch member 85
counterclockwise, and the releasable member 55 will move clockwise
changing the line of action of the overcenter springs 49 whereupon
the springs 49 will collapse the toggle 41, 45 and move the contact
carriers 37 of the three pole units to a tripped open position.
This movement will move the handle structure 63 to a position
intermediate the on and off positions to provide a visual
indication that the circuit breaker has been tripped.
Following a tripping operation, it is necessary to reset and
relatch the mechanism before the circuit breaker can be closed. In
order to reset the circuit breaker, the handle structure 63 is
moved counterclockwise from the intermediate position to an reset
position past the off position seen in FIG. 1. During this
movement, a pin portion 113 on the operating lever 51 engages a
shoulder 115 on the releasable member 115 to rotate the releasable
member 115 in a counterclockwise direction whereupon the free end
of the releaseable member engages a part 117 of the first latch
member 81 to pivot the first latch member 81 in a clockwise
direction about the pivot pin 83 to a reset position whereupon
spring means 119 biases the second latch member 85 to the latching
position and spring means 121 biases the third latch member 93 to
the latching position. During the resetting operating, the handle
structure 63 is moved to the reset position which reset position is
almost to the limit of movement of the operating handle structure
63 in the opening 67. During this movement, the shroud 81 on the
handle structure 63 engages a reset member 125, that comprises a
horizontal arm 127 and a generally vertical arm 129. The reset
member 125 is supported for pivotal movement about the axis 95.
Upon movement of the handle structure 63 to the reset position, the
shroud 71, engaging the arm 127 of the reset member 125, pivots the
reset member 125 in a clockwise (FIG. 1) direction whereupon the
arm 129, operating against the projection 103 (FIG. 4) of the
magnetic trip actuator 99, moves the armature 101 from the actuated
or tripping position seen in FIG. 4 to the initial or reset
position seen in FIG. 3 whereupon the magnetic trip actuator is
reset and will be maintained in the reset position in a manner to
be hereinafter described. Following a resetting operation, the
circuit breaker can be operated in the same manner as was
hereinbefore described. The manual, tripping and resetting
operations of the circuit breaker are more specifically described
in the above-mentioned patent application of Alfred E. Maier Ser.
No. 327,961.
The flux transfer magnetic trip actuator 99 (FIGS. 2-4) comprises a
U-shaped magnetic frame 133 of soft magnetic material such as iron.
There are two projecting end portions 135 on each of the legs of
the U-shaped frame 133, and the projecting portions 135 project
through openings in a magnetic plate 137 of soft magnetic material
such as iron. Two elongated bolts 141 (FIGS. 2-4) are threaded into
the plate 137 to secure the magnetic plate 137 and magnetic frame
parts 133 together to provide a magnetic frame that houses the
parts of the magnetic trip actuator 99. A pin 145 of non-magnetic
material such as brass, is provided with a reduced portion 147 that
extends through an opening in a magnetic pole piece 149 of soft
magnetic material such as iron, and through an opening in the end
part of the frame 133. The pin 145 is riveted over at 151 to secure
the pin 145 and pole piece 149 to the frame 133. As can be
understood with reference to FIG. 3, the pin 145 comprises a
shoulder part 153 that is drawn against the pole piece 149 to
secure the pole piece 149 and pin 145 in a stationary position when
the pin is riveted over at 151. A coil 157, that comprises a
conducting coil part 159 and an insulating cover 161, is positioned
over the pole piece 149. The armature 101, which is of soft
magnetic material such as iron, comprises a collar part 163. A coil
spring 165, which is supported over the armature 101, is disposed
between the coil 157 and collar part 163 to bias the armature 101
toward an extended actuating position. As can be understood with
reference to FIG. 3, the armature 101 comprises a tubular part and
the armature fits over the non-magnetic pin 145 which serves as a
bearing support permitting rectilinear movement of the armature 101
on the pin 145. The armature 101 comprises a first reduced end
portion that fits through an opening 169 in the magnetic plate 137.
A pair of permanent magnet members 171 and 173 are disposed on
opposite sides of the armature 101 and magnetically held in place
against the opposite legs of the magnetic frame 133.
In each pole unit of the circuit breaker, a current sensing
transformer 175 is disposed over the conductor 11 to sense the
overload current and operate through another transformer (not
shown) and a static circuit supported on a static circuit board
177, to energize the coil 157 of the magnetic trip actuator to
release of the armature 101 to thereby effect a tripping operation
of the circuit breaker in response to overload current conditions
above a predetermined value. The tripping operation is more
specifically described in the patent applications of Alfred E.
Maier et al Ser. No. 327,961, and Alan B. Shimp Ser. No.
327,973.
Referring to FIGS. 1 and 3, the magnetic trip actuator 99 is shown
therein in the initial or non-tripping position. The armature 101
is maintained in this position against the bias of the spring 165
by the magnetic flux that is supplied by the permanent magnets 171,
173. The magnetic flux from the permanent magnet 171 works in a
magnetic circuit that extends from the permanent magnet 171 through
the magnetic frame part 133, the pole piece 149, the armature 101,
the collar 163 of the armature 101, through the gap between the
collar 163 of the armature and the permanent magnet 171, and back
through the permanent magnet 171. The magnetic flux from the
permanent magnet 173 works in a magnetic circuit from the permanent
magnet 173 through the magnetic frame part 133, the magnetic pole
piece 149, the armature 101, the collar portion 163 of the
armature, the air gap between the collar portion 163 and the
permanent magnet 173, back through the permanent magnet 173. The
magnetic flux from the permanent magnets 171, 173 is strong enough
to maintain the armature 101 in the initial or non-tripping
position, abutting the pole piece 149, against the bias of the coil
spring 165 which biases the armature 101 toward an actuating or
tripping position. When the coil 157 is energized by a DC current
upon the occurrence of an overload current condition above a
predetermined value through the circuit breaker, the reluctance of
the above-mentioned magnetic holding circuits is increased and the
spring 165 overcomes the holding force of the permanent magents
171, 173 and moves the armature 101 to the right to the actuating
or tripping position seen in FIG. 4, which movement is limited by
the engagement of the collar portion 163 of the armature 101 with
the magnetic plate 137. Upon movement of the armature 101 to the
tripping position seen in FIG. 4, the circuit breaker mechanism is
released and the circuit breaker is tripped open in the same manner
as was hereinbefore described. With the armature 101 in the
tripping position, the flux from the permanent magnet member 171
operates through the adjacent leg of the magnetic frame 133, the
magnetic plate 137, the radial air gap at the opening 169, the
armature 101, the air gap between the collar portion 163 of the
armature 101 and the permanent magnet member 171, back through the
permanent magnet member 171. The Flux from the permanent magnet
member 173 operates through the lower leg (FIG. 3) of the magnetic
frame part 133, the magnetic plate 137, the radial air gap at the
opening 169, the armature 101, the collar portion 163 of the
armature 101, the air gap between the collar portion 163 of the
armature 101 and the permanent magnet member 173, back through the
permanent magnet 173. The armature 101 will remain in the actuating
or tripping position seen in FIG. 4 until the circuit breaker is
reset and relatched in the same manner hereinbefore described
during which operation the reset member 125 (FIG. 1) is pivoted in
a clockwise direction to move against the projecting part 103 of
the armature 101 to move the armature 101 back to the initial
position seen in FIG. 3. When the armature 101 reaches the initial
position seen in FIG. 3, the permanent magnets 171, 173 will
maintain the armature 101 in the initial position against the bias
of the spring 165 in the same manner as was hereinbefore described.
The armature 101 will remain in the initial position until the coil
157 is again energized to effect another tripping operation.
Referring to FIG. 3, it can be understood that during the assembly
operation, the pole piece 149 and coil 157 are moved down into
place in the U-shaped frame part 133 and thereafter the spring 165,
armaure 163 and non-magnetic pin 145 are moved into position. The
end of the pin 145 protrudes through the opening in the frame 133
and is thereafter riveted over to secure the parts in position.
Thereafter the permanent magnets 171, 173 are set in place and the
magnetic frame plate 137 is moved into position receiving the leg
parts 135 in openings thereof whereupon the bolts 141 are threaded
into the magnetic plate 137 to hereby secure the assembly together
as shown in FIGS. 2-4.
The design of the magnetic trip actuator 99 provides for a
relatively simple construction that is easily assembled and that
provides an armature of reduced mass that is less likely to be
accidentally released under physical shock conditions or under
stray magnetic fields. Armature acceleration is also enhanced by
the reduced mass of the armature. The armature, which is mounted
for generally rectilinear movement on the non-magnetic support pin,
is well aligned with the pole piece 149 providing a good flat
mating surface between the armature and the pole piece in the
initial position of the armature. The provision of the second
magnetic circuit through the radial air gap of the back plate
enhances increased speed of flux transfer and therefore faster
switching speed during tripping operations and cooperates with the
advantage of having the armature of reduced mass to enable a
lighter biasing spring for biasing the armature toward the tripping
position which also enables the utilization of smaller permanent
magnets in the construction. Although the magnetic trip actuator is
herein specifically disclosed in combination with a molded-case
type circuit breaker, it is to be understood that the magnetic trip
actuator could be utilized with other apparatus and with other
types of circuit breakers or switching devices.
* * * * *