Information
-
Patent Grant
-
6750743
-
Patent Number
6,750,743
-
Date Filed
Tuesday, May 13, 200321 years ago
-
Date Issued
Tuesday, June 15, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 335 16
- 335 35
- 335 132
- 335 135
- 335 137
- 335 147
- 335 165
- 335 166
- 335 172
- 335 195
- 335 196
- 335 202
- 200 306
- 218 22
- 218 35
- 218 157
- 337 8
- 337 110
-
International Classifications
- H01H7366
- H01H7140
- H01H902
-
Abstract
A circuit breaker for a multi-pole electrical distribution circuit includes a cassette associated with each pole in the multi-pole electrical distribution circuit. Each cassette includes a housing, a pair of electrical contacts disposed in the housing, and a thermal and magnetic trip unit supported by the housing. The housing includes a first compartment having the electrical contacts disposed therein and a second compartment having at least a portion of the thermal and magnetic trip unit disposed therein. A wall separates the first and second compartments for isolating the second compartment from gasses generated by separation of the first and second contacts. A duct adjacent to the second compartment allows the gasses to pass to an exterior portion of the housing. The housing includes a pair of opposing slots formed therein for receiving edges of a load terminal. A lever has a first end disposed proximate an end of a bimetallic element and a second end disposed proximate an armature in the magnetic assembly of the trip unit. The lever is rotated by at least one of the bimetallic element and the armature to unlatch an operating mechanism.
Description
BACKGROUND OF THE INVENTION
The present invention relates to circuit breakers and, more particularly, to circuit breakers including thermal and magnetic trip units.
Circuit breakers typically provide instantaneous, short time, and long-time protection against high currents produced by various conditions such as short-circuits, ground faults, overloads, etc. In a circuit breaker, a trip unit is the device that senses current (or other electrical condition) in the protected circuit and responds to high current conditions by tripping (unlatching) the circuit breaker's operating mechanism, which in turn separates the circuit breaker's main current-carrying contacts to stop the flow of electrical current to the protected circuit. Such trip units are required to meet certain standards, e.g., UL/ANSI/IEC, which define trip time curves specifying under what conditions a trip must occur, i.e., short time, long time, instantaneous, or ground fault, all of which are well known.
One type of trip unit is known as a thermal and magnetic trip unit. A thermal and magnetic trip unit includes a magnetic assembly and a thermal assembly. The thermal assembly typically includes a bimetallic element through which electrical current flows. As current flows through the bimetallic element, the bimetallic element heats up and bends due to the different coefficients of expansion in the metals used to form the bimetallic element. If the temperature rise is sufficient, the bimetallic element bends enough to move an associated trip latch, which unlatches the operating mechanism to separate the main current-carrying contacts. The thermal assembly is typically used to sense an overload condition.
The magnetic assembly typically includes a magnet core (yoke) disposed about a current carrying strap, an armature (lever) pivotally disposed near the core, and a spring arranged to bias the armature away from the magnet core. Upon the occurrence of a short circuit condition, very high currents pass through the strap. The increased current causes an increase in the magnetic field about the magnet core. The magnetic field acts to rapidly draw the armature towards the magnet core, against the bias of the spring. As the armature moves towards the core, the end of the armature moves an associated trip latch, which unlatches the operating mechanism causing the main current-carrying contacts to separate.
Thermal and magnetic trip units must be calibrated to ensure that the circuit breaker trips at the appropriate current conditions. Calibration typically includes adjusting a distance between the bimetal and its associated trip latch and between the armature and its associated trip latch. However, establishing and maintaining calibration can be made difficult due to relative motion of the operating mechanism and the trip unit.
BRIEF SUMMARY OF THE INVENTION
The above discussed and other drawbacks and deficiencies are overcome or alleviated by a circuit breaker for a multi-pole electrical distribution circuit, the circuit breaker including a cassette associated with each pole in the multi-pole electrical distribution circuit. Each cassette includes a housing, a pair of electrical contacts disposed in the housing, and a thermal and magnetic trip unit supported by the housing. The thermal and magnetic trip unit initiates separation of the pair of electrical contacts in response to an overcurrent condition in the multi-pole electrical distribution circuit.
In one embodiment, the housing includes a first compartment having the pair of electrical contacts disposed therein and a second compartment having at least a portion of the thermal and magnetic trip unit disposed therein. The first and second compartments have a wall disposed therebetween for isolating the second compartment from gasses generated by separation of the pair of electrical contacts. The first compartment may be in fluid communication with an exterior portion of the housing through a duct adjacent the second compartment, such that the gasses pass through the channel to the exterior portion of the housing.
In another embodiment, an end of the housing includes a pair of opposing slots formed therein for receiving edges of a load terminal. The edges of the load terminal may each include a detent formed thereon for retaining the edges within the pair of opposing slots.
Another embodiment includes a lever having a first end disposed proximate an end of a bimetallic element and a second end disposed proximate an armature in the magnetic assembly of the trip unit. At least one of the bimetallic element and the armature rotate the trip lever to unlatch an operating mechanism. The lever and the bimetallic element may extend into the second compartment through an opening in the top of the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings wherein like elements are numbered alike in the several Figures:
FIG. 1
is an isometric view of a molded case circuit breaker employing;
FIG. 2
is an exploded view of the circuit breaker of
FIG. 1
;
FIG. 3
is a perspective view of circuit breaker cassettes including a compartment for an integrated thermal and magnetic trip unit;
FIG. 4
is a perspective view of one of the circuit breaker cassettes including an integrated thermal and magnetic trip unit;
FIG. 5
is a perspective view of a load terminal of the circuit breaker cassette of
FIG. 4
;
FIG. 6
is a partial cut-away view of the circuit breaker cassette including the integrated thermal and magnetic trip unit of
FIG. 4
;
FIG. 7
is a plan view of a magnetic assembly for the thermal and magnetic trip unit;
FIG. 8
is a schematic depiction of the thermal and magnetic trip unit and a trip lever of the operating mechanism; and
FIG. 9
is a perspective view of the trip lever positioned relative to a cassette housing.
DETAILED DESCRIPTION OF THE INVENTION
Referring to
FIG. 1
, a top perspective view of a molded case circuit breaker
20
is generally shown. Molded case circuit breaker
20
is generally interconnected within a protected circuit between multiple phases of a power source (not shown) at line end
21
and a load to be protected (not shown) at load end
23
. Molded case circuit breaker
20
includes a base
26
, a mid cover
24
and a top cover
22
having a toggle handle (operating handle)
44
extending through an opening
28
.
FIG. 2
shows an exploded view of the circuit breaker
20
. Disposed within base
26
are a number of cassettes
32
,
34
, and
36
, corresponding to the number of poles (phases of current) in the electrical distribution circuit into which circuit breaker
20
is to be installed. The example shown corresponds to a 3-pole system (i.e., three phases of current), and has three cassettes
32
,
34
and
36
disposed within base
26
. It is contemplated that the number of cassettes can vary corresponding to the number of phases. Cassettes
32
,
34
and
36
are commonly operated by an operating mechanism
38
via a cross pin
40
. Cassettes
32
,
34
,
36
are typically formed of high strength plastic thermoset material and each include opposing sidewalls
46
,
48
. Sidewalls
46
,
48
have an arcuate slot
52
positioned and configured to receive and allow the motion of cross pin
40
by action of operating mechanism
38
.
Operating mechanism
38
is shown positioned atop and supported by cassette
34
, which is generally disposed intermediate to cassettes
32
and
36
. It will be appreciated, however, that operating mechanism
38
may be positioned atop and supported by any number of cassettes
32
,
34
, and
36
. Toggle handle
44
of operating mechanism
38
extends through openings
28
and
30
and allows for mating electrical contacts disposed within each of the cassettes to be separated and brought into contact by way of movement of toggle handle
44
between “open” and “closed” positions. Operating mechanism
38
also includes a trip latch system
50
, which allows a spring mechanism
51
in the operating mechanism
38
to be unlatched (tripped) to separate the contacts in each of the cassettes
32
,
34
and
36
by way of spring force applied to rotors in each of the cassettes
32
,
34
, and
36
via cross pin
40
. More specifically, cross pin
40
extends through an aperture
53
in a plate
55
and through apertures
166
disposed in rotor assemblies
164
(see
FIG. 6
) in each of the cassettes
32
,
34
, and
36
. Plate
55
is pivotally mounted to a fixed pivot point
57
and is linked to a spring in the operating mechanism
38
. Unlatching the operating mechanism
38
releases the spring to apply a force to pivot the plate
55
about its pivot point
57
. As the plate
55
pivots about pivot point
57
, the plate
55
drives the rotors via the cross pin
40
to separate the contacts in each of the cassettes. The spring mechanism
51
may be reset to a latched position by operation of the toggle handle
44
to a “reset” position. Operating mechanism
38
may operate, for example, as described in U.S. Pat. No. 6,218,919 entitled “Circuit Breaker Latch Mechanism With Decreased Trip Time”.
Referring now to
FIG. 3
, a perspective view of circuit breaker cassettes
32
,
34
, and
36
including compartments
54
for an integrated thermal and magnetic trip unit are shown. Each of the cassettes
32
,
34
,
26
include a housing
60
formed by two half-pieces
62
,
64
joined by fasteners disposed through seven apertures
66
in the housing
60
. A load-side end
68
of the housing
60
includes an outlet port
70
for an arc gas duct
72
formed in the housing
60
. Disposed in the housing
60
above the outlet port
70
are a pair of opposing slots
74
that extend along an internal portion of sidewalls
46
and
48
.
FIG. 4
is a perspective view of one of the circuit breaker cassettes
32
,
34
, or
36
supporting an integrated thermal and magnetic trip unit
80
. Thermal and magnetic trip unit
80
includes a magnet assembly
82
and a bimetallic element
84
coupled to an end of a load terminal
86
. Edges
88
of load terminal
86
are received within the opposing slots
74
formed in the housing
60
of the cassette
32
,
34
, or
36
. A tab
90
extends from load terminal
86
for connection to wiring, a lug, or the like to form an electrical connection with the protected load. Fasteners
92
,
94
secure the magnetic assembly
82
to the load terminal
86
, and secure the load terminal
86
to a flux shunt
96
(shown in FIG.
6
). Flux shunt
96
is a strip of magnetic material that extends along a length of the load terminal
86
, between the load terminal
86
and the bimetallic element
84
to prevent electromagnetic forces developed by current flowing through the load terminal
86
and bimetallic element
84
from deflecting the bimetallic element
84
.
Magnet assembly
82
includes a core
98
that extends around the bimetallic element
84
, an armature
100
pivotally disposed on a leg
180
of the core
98
, and a spring assembly
102
disposed on the armature
100
. Spring assembly
102
acts to bias armature
100
away from a leg
188
of the core
98
. A threaded set screw
104
extends through a hole in the load terminal
86
and a threaded hole in the core
98
, and comes into contact with the bimetallic element
84
. The set screw
104
is used for calibrating the bimetallic element
84
. In some cases where a high resistance low amp bimetal is used, an insulator is inserted between the set screw
104
and bimetallic element
84
to prevent a parallel current path through the set screw
104
from damaging to the bimetal.
FIG. 5
is a perspective view of the load terminal
86
. Load terminal
86
includes a substantially flat portion
120
along which edges
88
are formed. Holes
122
disposed in the flat portion
120
receive fasteners
92
,
94
and set screw
104
(FIG.
4
). One end of the flat portion
120
includes the tab
90
extending substantially perpendicular therefrom, and an opposite end of the flat portion
120
is shaped to include an offset
124
. The bimetallic element
84
, shown in phantom, is attached to the load terminal
86
at the offset
124
using brazing, welding, fasteners, or the like. Each of the side edges
88
has a detent
126
formed thereon. The detent
126
provides an interference fit between the side edges
88
of the load terminal
86
and the slots
74
in the housing
60
to secure the side edges
88
within the slots
74
and thus prevent the load terminal
86
from deflecting under thermal stresses and mechanical loads. By preventing the load terminal
86
from deflecting and, thus, moving relative to the housing
60
, movement of the thermal and magnetic trip unit
80
, which is secured to the load terminal
86
, will also be prevented. In the embodiment shown, detents
126
are stamped tabs formed in the flat portion.
Referring to
FIG. 6
, the cassette
32
,
34
, or
36
is shown with one half-piece
62
removed. Supported within cassette
32
,
34
, or
36
is a rotary contact assembly
150
, which includes two mating pairs of electrical contacts, each pair having one contact
152
mounted on a contact arm
154
and another contact
156
mounted on one of a load strap
158
or a line strap
160
. Load strap
158
is connected to a flexible braid
162
, which is in turn coupled to an end of the bimetallic element
84
. When the contacts
152
,
156
are in a closed position (i.e., placed in intimate contact), electrical current passes between the line an load sides of the electrical distribution circuit through the line strap
160
, the first pair of electrical contacts
152
,
156
, the contact arm
154
, the second pair of electrical contacts
152
,
156
, the load strap
158
, the flexible braid
162
, the bimetallic element
84
, and the load terminal
86
.
The contact arm
154
is mounted within a rotor assembly
164
, which is pivotally supported within the housing
60
. A hole
166
in rotor assembly
164
accepts cross pin
40
, which transmits the force of the operating mechanism
38
to pivot the rotor assembly
164
about its axis for separating the contacts
152
,
156
to interrupt the flow of electrical current to the load terminal
86
. The contact arm
154
may also pivot within the rotor assembly
164
, thus allowing instantaneous separation of the contacts
152
,
156
by the electromagnetic force generated in response to certain overcurrent conditions, such as dead short circuit conditions. The reverse loop shape of the line and load straps
158
,
160
directs the electromagnetic force to separate the contacts
152
,
156
.
As the contacts
152
,
156
move apart from each other to interrupt the flow of electrical current, an arc is formed between the contacts
152
,
156
, and the arc generates ionized gas. An arc arrestor
168
is supported in the housing proximate each pair of contacts
152
,
156
. The arc arrestor
168
includes a plurality of plates
170
disposed therein, which acts to attract, cool and de-ionize the arc to rapidly extinguish the arc. The gasses generated by the arc pass from a compartment
172
containing the contacts
152
,
156
, through the arc arrestor
168
and exhaust outside the housing
60
via ducts
72
,
174
. Duct
72
is formed adjacent to the compartment
54
for the integrated trip unit
80
. A wall
176
extends inward from each of the sidewalls
46
,
48
to form the duct
72
and to isolate the compartment
54
for the trip unit
80
from the compartment
172
including the contacts
152
,
156
. Other features that extend inward from each of the sidewalls
46
,
48
include supports for the line and load straps
158
,
160
, support for the rotor assembly
164
, and support for the arc arrestors
168
.
Referring to
FIG. 7
, a plan view of the electro magnetic assembly
82
for the thermal and magnetic trip unit
80
is shown with the armature
100
in an open position. Armature
100
is generally L-shaped and is pivotally coupled to one leg
180
of the magnet core
98
. The magnet core
98
is generally U-shaped and is disposed around the bimetallic element
84
. A portion of armature
100
extends within an aperture
182
formed in the leg
180
of the magnet core
98
and is secured therein by an end of a bracket
184
, which is fastened to the armature
100
. A spring
186
extends between an opposite end of the bracket
184
and the leg
180
of the magnet core
98
to bias the armature
100
in the open position, away from another leg
188
of the magnet core
98
.
As electrical current flows through the bimetallic element
84
, a magnetic flux is created across gaps (A) and (B) which draws armature
100
toward the leg
188
of the magnet core
98
. As the armature
100
moves toward the leg
188
, it acts on a trip lever
190
. When the current exceeds a predetermined amount (e.g., 12.5 times the breaker current rating), the magnetic force on the armature
100
overcomes the spring force
186
, and the armature
100
pivots to move the trip lever
190
.
The calibration screw adjusts the distance between the trip lever
190
and the bimetallic element
84
to set the distance of travel of the bimetal needed to move the trip lever
190
.
FIG. 8
is a schematic depiction of the interaction between the thermal and magnetic trip unit
80
and the trip lever
190
.
FIG. 9
is a perspective view of the trip lever
190
positioned relative to a cassette housing
60
. As shown in FIG.
8
and
FIG. 9
, trip lever
190
includes a first end
192
extending from a bar
198
and disposed proximate an end of the bimetallic element
84
, and a second end
194
extending from bar
198
and disposed proximate the armature
100
. The trip lever
190
and the bimetallic element
84
extend into the compartment
54
through an opening in the top of the housing
60
. As discussed above, movement of the armature
100
in response to a predetermined amount of current in the bimetallic element
84
causes the armature
100
to move the trip lever
190
. The trip lever
190
may also be moved by the bimetallic clement
84
itself, which forms the thermal portion of the thermal and magnetic assembly
80
. As current flows through the bimetallic element
84
, the bimetallic element
84
heats up and bends due to the different coefficients of expansion in the metals used to form the bimetallic element
84
. As the bimetallic element
84
bends due to increased temperature, it comes into contact and moves the trip lever
190
.
Movement of the trip lever
190
by either the armature
100
or the bimetallic element
84
causes the trip lever
190
to rotate in the direction indicated by the arrow about a pivot point
196
. Trip lever
190
may be coupled to the trip latch system
50
of the operating mechanism
38
using any suitable arrangement such that rotation of the trip lever
190
will cause the spring mechanism
51
to become unlatched to separate the contacts
152
,
156
. For example, the trip latch system
50
may operate as described in U.S. Pat. No. 6,218,919 entitled “Circuit Breaker Latch Mechanism With Decreased Trip Time” where trip latch system
50
would include a primary latch
200
releasably coupled to the operating mechanism
38
via a cradle
202
and biased against a secondary latch
204
affixed to trip lever
190
such that rotation of the trip lever
190
(in the direction indicated by the arrow) by either the bimetallic element
84
or armature
100
will cause the secondary latch
204
to pivot away from and out of contact with the primary trip latch
200
. Without secondary latch
204
to restrain movement of the primary latch
200
, the primary latch
200
moves to release the cradle
202
and, thus, unlatch the spring mechanism
51
, which, in turn, separates the electrical contact pairs
152
,
156
in each of the cassettes
32
,
34
, and
36
. As best seen in
FIG. 9
, bar
198
includes a number of trip levers
190
disposed thereon equal to the number of cassettes
32
,
34
and
36
in the circuit breaker
20
. Thus, the movement of any trip lever
190
will cause rotation of the bar
198
about pivot point
196
to trip the circuit breaker
20
.
Integrating the thermal and magnetic trip unit
80
with the cassette housing
60
provides many advantages over the prior art arrangement, in which the thermal and magnetic trip unit are mounted separately from the cassette in the base. First, integrating the trip unit
80
with the housing
60
allows for a reduction of parts, as a separate housing for the trip unit
80
is not needed. Second, integrating the trip unit
80
with the housing
60
provides for a more accurate alignment of the trip unit
80
, operating mechanism
38
, and cassette
32
,
34
or
36
because the cassette
32
,
34
or
36
is the common datum for both the operating mechanism
38
and the trip unit
80
. Third, integrating the trip unit
80
with housing
60
allows for easy assembly, as the cassettes
32
,
34
and
36
, operating mechanism
38
, and trip units
80
can be inserted into the base
26
as a unit. Finally, because the trip unit
80
is mounted in the thermoset material of the housing
60
, which provides minimal deflection due to thermal heating and mechanical loading, the trip unit
80
remains aligned with the cassette
32
,
34
or
36
and operating mechanism
38
under thermal heating and mechanical loading and, as a result, calibration of the trip unit
80
can be maintained under these conditions. The integrated trip unit
80
is supported in the most robust part of the breaker
20
, thus making the trip unit
80
insensitive to mechanical forces on the load terminals during the attachment of cables so as to prevent changes to the calibration of the integrated trip unit
80
.
The separation of compartments
54
and
172
ensures that the trip unit
80
is isolated from exposure to the hot arc gasses in the interrupter compartment
172
. Without separate compartments
54
and
172
, the hot arc gasses could result in damage to the bimetallic element
84
or braid
162
, which could affect calibration. The hot arc gasses could also create deposits on the latch surfaces that may prevent unlatching of the trip latch system
50
, or could result contamination causing dielectric breakdown between phases of opposite polarity.
It will be understood that a person skilled in the art may make modifications to the preferred embodiment shown herein within the scope and intent of the claims. While the present invention has been described as carried out in a specific embodiment thereof, it is not intended to be limited thereby but is intended to cover the invention broadly within the scope and spirit of the claims.
Claims
- 1. A circuit breaker for a multi-pole electrical distribution circuit, the circuit breaker including:a cassette associated with each pole in the multi-pole electrical distribution circuit, each cassette including: a housing, a pair of electrical contacts disposed in the housing, and a thermal and magnetic trip unit supported by the housing, the thermal and magnetic trip unit initiates separation of the pair of electrical contacts in response to an overcurrent condition in the multi-pole electrical distribution circuit.
- 2. The circuit breaker of claim 1, wherein the housing includes:a first compartment having the pair of electrical contacts disposed therein; and a second compartment having at least a portion of the thermal and magnetic trip unit disposed therein, the first and second compartments having a wall disposed therebetween for isolating the second compartment from gasses generated by separation of the pair of electrical contacts.
- 3. The circuit breaker of claim 2, wherein the first compartment is in fluid communication with an exterior portion of the housing through a duct adjacent the second compartment, the gasses generated by separation of the pair of electrical contacts pass through the duct to the exterior portion of the housing.
- 4. The circuit breaker of claim 1, wherein the housing is formed from a thermoset material.
- 5. The circuit breaker of claim 1, wherein an end of the housing includes a pair of opposing slots formed therein for receiving edges of a load terminal.
- 6. The circuit breaker of claim 5, wherein the edges of the load terminal each include a detent formed thereon for retaining the edges within the pair of opposing slots.
- 7. The circuit breaker of claim 1, wherein the thermal and magnetic trip unit includes:a bimetallic element electrically coupled to at least one of the electrical contacts; a core disposed proximate the bimetallic element, and an armature disposed proximate the core, wherein movement of at least one of the bimetallic element and the armature initiates separation of the pair of electrical contacts.
- 8. The circuit breaker of claim 7, further comprising:an operating mechanism operably coupled to at least one of the electrical contacts, the operating mechanism separating the pair of electrical contacts in response to being unlatched; and a lever having a first end disposed proximate an end of the bimetallic element, a second end disposed proximate the armature, and wherein at least one of the bimetallic element and the armature rotate the lever to unlatch the operating mechanism.
- 9. The circuit breaker of claim 8, wherein the housing includes:a first compartment having the pair of electrical contacts disposed therein; and a second compartment having at least a portion of the thermal and magnetic trip unit disposed therein, the first and second compartments having a wall disposed therebetween for isolating the second compartment from gasses generated by separation of the pair of electrical contacts, the lever and the bimetallic element extend into the second compartment through an opening in the top of the housing.
- 10. A circuit breaker including:a base; a plurality of cassettes disposed in the base, each cassette including: a housing, a pair of electrical contacts disposed in the housing, a load terminal electrically coupled to a first contact in the pair of electrical contacts, the load terminal supported by the housing, and a thermal and magnetic trip unit supported by the housing; and an operating mechanism operably coupled to a second contact in the pair of electrical contacts, wherein the thermal and magnetic trip unit unlatches the operating mechanism in response to a level of current flowing through the pair of electrical contacts, and the operating mechanism separates the first and second contacts in response to being unlatched by the thermal and magnetic trip unit.
- 11. The circuit breaker of claim 10, wherein the housing of at least one cassette supports the operating mechanism.
- 12. The circuit breaker of claim 10, wherein the housing includes:a first compartment having the pair of electrical contacts disposed therein; and a second compartment having at least a portion of the thermal and magnetic trip unit disposed therein, the first and second compartments having a wall disposed therebetween for isolating the second compartment from gasses generated by separation of the first and second contacts.
- 13. The circuit breaker of claim 12, wherein the first compartment is in fluid communication with an exterior portion of the housing through a duct adjacent the second compartment, the gasses generated by separation of the first and second contacts pass through the duct to the exterior portion of the housing.
- 14. The circuit breaker of claim 10, wherein the housing is formed from a thermoset material.
- 15. The circuit breaker of claim 10, wherein an end of the housing includes a pair of opposing slots formed therein for receiving edges of the load terminal.
- 16. The circuit breaker of claim 15, wherein the edges of the load terminal each include a detent formed thereon for retaining the edges within the pair of opposing slots.
- 17. The circuit breaker of claim 10, wherein the thermal and magnetic trip unit includes:a bimetallic element electrically coupled to the first contact; a core disposed proximate the bimetallic element; and an armature disposed proximate the core, wherein movement of at least one of the bimetallic element and the armature initiates separation of the pair of electrical contacts.
- 18. The circuit breaker of claim 17, wherein the operating mechanism includes a lever having a first end disposed proximate an end of the bimetallic element, a second end disposed proximate the armature, and wherein at least one of the bimetallic element and the armature rotate the lever to unlatch the operating mechanism.
- 19. The circuit breaker of claim 18, wherein the housing includes:a first compartment having the pair of electrical contacts disposed therein; and a second compartment having at least a portion of the thermal and magnetic trip unit disposed therein, the first and second compartments having a wall disposed therebetween for isolating the second compartment from gasses generated by separation of the first and second contacts, the lever and the bimetallic element extend into the second compartment through an opening in the top of the housing.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
3631369 |
Menocal |
Dec 1971 |
A |
5103198 |
Morel et al. |
Apr 1992 |
A |
6188036 |
Arnold |
Feb 2001 |
B1 |
6218919 |
Ciarcia et al. |
Apr 2001 |
B1 |