This application relates to tripping mechanisms for two-pole circuit breakers. Example embodiments include ground fault circuit interrupt two-pole residential circuit breakers, arc fault circuit interrupt two-pole residential circuit breakers, and combination arc fault and ground fault circuit interrupt two-pole residential circuit breakers.
In a first aspect, a two-pole circuit breaker is provided that includes an electronic pole disposed between a first mechanical pole and a second mechanical pole. The first mechanical pole includes a first armature, and the second mechanical pole includes a second armature. The first and second armatures each are adapted to rotate in a first plane. The electronic pole includes a trip mechanism having a first trip arm disposed adjacent the first armature and a second trip arm disposed adjacent the second armature. The first trip arm and the second trip arm are each adapted to rotate in a second plane substantially orthogonal to the first plane.
In a second aspect, an electronic pole is provided for use with a two-pole circuit breaker having a first mechanical pole and a second mechanical pole. The electronic pole includes a solenoid and a trip mechanism coupled to the first mechanical pole and the second mechanical pole. The trip mechanism includes a first trip arm having a first solenoid interface and a second trip arm having a second solenoid interface disposed adjacent the first solenoid interface. The solenoid is adapted to engage the first solenoid interface and the second solenoid interface to common trip the two-pole circuit breaker.
In a third aspect, a trip mechanism is provided for a two-pole circuit breaker that includes a first mechanical pole having a first armature adapted to rotate in a first plane, and a second mechanical pole having a second armature adapted to rotate in the first plane. The trip mechanism includes a first trip arm disposed adjacent the first armature and a second trip arm disposed adjacent the second armature. The first trip arm and the second trip arm are each adapted to rotate in a second plane substantially orthogonal to the first plane.
Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings.
Features of the present invention can be more clearly understood from the following detailed description considered in conjunction with the following drawings, in which the same reference numerals denote the same elements throughout, and in which:
Two-pole circuit breakers, such as residential two-pole circuit breakers, have two electrical branches or poles through which electrical power is provided to one or more loads. For example, in the United States, residential two-pole circuit breakers typically provide 240 volts instead of 120 volts to devices or appliances such as electric dryers, water heaters, well pumps, and/or electric ranges. Previously known two-pole circuit breakers typically include an electronic pole disposed between first and second mechanical poles. A trip bar typically extends through the electronic pole and communicates with the first and second mechanical poles.
If an overcurrent or short circuit is sensed in one pole, the faulted mechanical pole unlatches, and the pole trips. In addition, the electronic pole may include an arc fault or a ground fault detector circuit that continuously monitors current flowing in each mechanical pole. If an arc fault or a ground fault occurs in either mechanical pole, the detector circuit activates a single wound solenoid to trip and unlatch the faulted mechanical pole. As the faulted mechanical pole unlatches, the trip bar rotates, and the rotation causes the other mechanical pole to trip and unlatch.
Such a previously known electrical/mechanical tripping mechanism seeks to ensure that when either mechanical pole trips, the other pole also trips, known as a “common trip.” A two-pole circuit breaker that does not common trip could potentially be a safety concern to end users, and must be avoided. Previously known two-pole circuit breakers that include a trip bar, however, have numerous disadvantages.
In particular, use of a trip bar may require several production instructions during manufacture, and special fixtures may be needed to ensure that the trip bar is correctly assembled. In addition, key features of the trip bar may have very tight tolerances that need close monitoring to ensure that required drawing specifications are satisfied.
Moreover, during assembly of the circuit breaker, numerous components within the circuit breaker typically must be precisely aligned to properly align the trip bar. Improper trip bar alignment could result in binding conditions that prevent the trip bar (and therefore the circuit breaker) from properly operating. As a result, previously known two-pole circuit breaker designs often require substantial monitoring of the trip bar during assembly. Apparatus and methods in accordance with this invention provide a tripping mechanism for a two-pole circuit breaker that common trips, but that does not include a trip bar.
Referring to
As shown in
As described in more detail below, first trip arm end 34L is adapted to extend into first mechanical pole aperture 26L adjacent first armature 20L, and second trip arm end 34R is adapted to extend into second mechanical pole aperture 26R adjacent second armature 20R. In addition, electronic pole 12 optionally includes a pigtail 38 which may be used to connect a neutral conductor (not shown) in circuit breaker 10 to a load center or panel board neutral bar (not shown).
Referring now to
First moveable bus 44L is connected to a first bi-metal strip 54L by a first flexible conductor 60L. A first load terminal 62L is connected to a top end of first bi-metal strip 54L, and also is coupled to a first short-circuit sensing element 64L. As described in more detail below, first bi-metal strip 54L and first short-circuit sensing element 64L are used to provide overcurrent and instantaneous tripping functions, respectively. A first channel 66L directs any arc discharge gas resulting from a short circuit away from first mechanical pole 14L. First cradle 40L includes a first end 68L disposed adjacent first projection 58L of first armature 20L, and a first cradle feature 70L adjacent first armature 20L.
First handle 18L is coupled to an upper end of first moveable bus 44L, and may be used to selectively turn first mechanical pole 14L ON and OFF, and thereby selectively CLOSE and OPEN, respectively, first moveable contact 46L and first stationary contact 52L. In particular, moving first handle 18L to the ON position causes first moveable bus 44L to move in a clockwise direction, which causes first moveable contact 46L and first stationary contact 52L to CLOSE. In contrast, moving first handle 18L to the OFF position causes first moveable bus 44L to move in a counter-clockwise direction, which causes first moveable contact 46L and first stationary contact 52L to OPEN.
A latch system of first mechanical pole 14L activates when first handle 18L is moved from the OFF position to the ON position. In particular, as first handle 18L is rotated towards the ON position, first cradle 40L rotates counter-clockwise. As first cradle 40L rotates, first end 68L rotates past first projection 58L of first armature 20L. First armature 20L rotates clockwise towards first cradle 40L as a result of first compression spring 56L pushing on the top of first armature 20L, and first projection 58L of first armature 20L passes under first end 68L of first cradle 40L. When first handle 18L is released, first cradle 40L rotates clockwise until first end 68L of first cradle 40L engages first projection 58L of first armature 20L, latching first mechanical pole 14L ON.
Although not shown in
Second moveable bus 44R is connected to a second bi-metal strip 54R by a second flexible conductor 60R. A second load terminal 62R is connected to a top end of second bi-metal strip 54R, and also is coupled to a second short-circuit sensing element 64R. As described in more detail below, second bi-metal strip 54R and second short-circuit sensing element 64R are used to provide overcurrent and instantaneous tripping functions, respectively. A second channel 66R directs any arc discharge gas resulting from a short circuit away from second mechanical pole 14R. Second cradle 40R includes a second end 68R disposed adjacent second projection 58R of second armature 20R, and a second cradle feature 70R adjacent second armature 20R.
Second handle 18R is coupled to an upper end of second moveable bus 44R, and may be used to selectively turn second mechanical pole 14R ON and OFF, and thereby selectively CLOSE and OPEN, respectively, second moveable contact 46R and second stationary contact 52R. In particular, moving second handle 18R to the ON position causes second moveable bus 44R to move in a clockwise direction, which causes second moveable contact 46R and second stationary contact 52R to CLOSE. In contrast, moving second handle 18R to the OFF position causes second moveable bus 44R to move in a counter-clockwise direction, which causes second moveable contact 46R and second stationary contact 52R to OPEN.
A latch system of second mechanical pole 14R activates when second handle 18R is moved from the OFF position to the ON position. In particular, as second handle 18R is rotated towards the ON position, second cradle 40R rotates counter-clockwise. As second cradle 40R rotates, second end 68R rotates past second projection 58R of second armature 20R. Second armature 20R rotates clockwise towards second cradle 40R as a result of second compression spring 56R pushing on the top of second armature 20R, and second projection 58R of second armature 20R passes under second end 68R of second cradle 40R. When second handle 18R is released, second cradle 40R rotates clockwise until second end 68R of second cradle 40R engages second projection 58R of second armature 20R, latching second mechanical pole 14R ON.
First mechanical pole 14L remains latched ON until first handle 18L is moved to the OFF position, or until an overload condition or a short circuit condition causes the latch mechanism to disengage and trip first mechanical pole 14L. As described in more detail below, in embodiments in which two-pole circuit breaker 10 also includes ground fault and/or arc fault circuit detection functions, a ground fault and/or an arc fault also cause the latch mechanism to disengage and trip first mechanical pole 14L.
During an overload condition, current flowing through the breaker causes first bi-metal strip 54L to heat up and deflect, which causes first armature 20L to rotate in a counter-clockwise direction about first armature pivot 22L. As first armature 20L rotates, first top surface 74L pulls away from first surface 72L, decreasing the overlap area of the two surfaces, as shown in
When the surface area overlap decreases to about zero, first cradle 40L rotates clockwise about first cradle pivot 42L, and first extension spring 48L rotates first moveable bus 44L counter-clockwise to separate first moveable contact 46L from first stationary contact 52L, unlatching first mechanical pole 14L. In the unlatched OFF configuration, first movable contact 46L and first stationary contact 52L are OPEN, as shown in
Likewise, during a short-circuit condition, current flowing through the breaker causes a magnetic field of first short-circuit sensing element 64L to increase, which causes first armature 20L to rotate in a counter-clockwise direction about first armature pivot 22L, and the surface area overlap between first top surface 74L of first armature 20L and first surface 72L of first cradle 40L decreases to about zero. As a result, first cradle 40L rotates clockwise about first cradle pivot 42L, and first extension spring 48L rotates first moveable bus 44L counter-clockwise to separate first moveable contact 46L from first stationary contact 52L, unlatching first mechanical pole 14L. In the unlatched OFF configuration, first movable contact 46L and first stationary contact 52L are OPEN, as shown in
Referring now to
In addition, as shown in
Bottom element 104 includes a first post 124L for slidingly receiving first trip arm journal 110L, and a second post 124R for slidingly receiving second trip arm journal 110R. Top element 102 securingly attaches to bottom element 104, and constrains first trip arm 32L and second trip arm 32R. First trip arm 32L is adapted to rotate about first post 124L, and second trip arm 32R is adapted to rotate about second post 124R. As first trip arm 32L rotates (e.g., counterclockwise), first trip arm interface 118L engages second trip arm interface surface 122R, causing second trip arm 32R to rotate in an opposite (e.g., clockwise direction), and vice-versa. Likewise, as second trip arm 32R rotates (e.g., clockwise), second trip arm interface 118R engages first trip arm interface surface 122L, causing first trip arm 32L to rotate in an opposite (e.g., counter-clockwise direction), and vice-versa.
Bottom element 104 also may include side posts 126L, 126R, 128L and 128R for positioning and securing trip mechanism 30 in complementary journals (not shown) in electronic pole 12. Persons of ordinary skill in the art will understand that alternative techniques may be used to position and secure trip mechanism 30 in electronic pole 12. As shown in
In particular,
As shown in
As shown in
As first trip arm 32L rotates in a clockwise direction, first trip arm interface 118L engages second trip arm interface surface 122R (not shown), causing second trip arm 32R to rotate in a counter-clockwise direction about second trip arm journal 110R. As shown in
Referring to
When the surface area overlap for first mechanical pole 14L and second mechanical pole 14R decrease to about zero, first cradle 40L rotates clockwise about first cradle pivot 42L, and first extension spring 48L rotates first moveable bus 44L counter-clockwise to separate first moveable contact 46L from first stationary contact 52L, unlatching first mechanical pole 14L, as shown in
Likewise, second cradle 40R rotates clockwise about second cradle pivot 42R, and second extension spring 48R rotates second moveable bus 44R counter-clockwise to separate second moveable contact 46R from second stationary contact 52R, unlatching second mechanical pole 14R, as shown in
Thus, as shown in
In addition to tripping on overcurrent or short circuit faults, two-pole circuit breakers in accordance with this invention also may trip on arc faults and/or ground faults. For example, electronic pole 12 may include an arc fault and/or a ground fault detector circuit (not shown) that continuously monitors current flowing in each mechanical pole. Referring to
In particular, referring now to
As shown in
As first armature 20L continues to rotate in a counter-clockwise direction about first armature pivot 22L, second armature 20R continues to rotate in a counter-clockwise direction about second armature pivot 22R. In addition, first top surface 74L pulls away from first surface 72L, and second top surface 74R pulls away from second surface 72R.
When the surface area overlap for first mechanical pole 14L and second mechanical pole 14R decrease to about zero, first cradle 40L rotates clockwise about first cradle pivot 42L, and first extension spring 48L rotates first moveable bus 44L counter-clockwise to separate first moveable contact 46L from first stationary contact 52L, unlatching first mechanical pole 14L, as shown in
Likewise, second cradle 40R rotates clockwise about second cradle pivot 42R, and second extension spring 48R rotates second moveable bus 44R counter-clockwise to separate second moveable contact 46R from second stationary contact 52R, unlatching second mechanical pole 14R, as shown in
Thus, as shown in
In accordance with this invention, dimensions of second armature interface 114R may be selected to increase the moment arm and reduce the amount of force required to de-latch second armature 20R. Likewise, dimensions of first armature interface 114L may be selected to increase the moment arm and reduce the amount of force required to de-latch first armature 20L.
The foregoing merely illustrates the principles of this invention, and various modifications can be made by persons of ordinary skill in the art without departing from the scope and spirit of this invention.
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