CA2004181A1 - Electrical circuit breaker handle locking apparatus - Google Patents
Electrical circuit breaker handle locking apparatusInfo
- Publication number
- CA2004181A1 CA2004181A1 CA002004181A CA2004181A CA2004181A1 CA 2004181 A1 CA2004181 A1 CA 2004181A1 CA 002004181 A CA002004181 A CA 002004181A CA 2004181 A CA2004181 A CA 2004181A CA 2004181 A1 CA2004181 A1 CA 2004181A1
- Authority
- CA
- Canada
- Prior art keywords
- electrical
- operating lever
- circuit breaker
- electrical circuit
- handle arm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
- H01H71/10—Operating or release mechanisms
- H01H71/50—Manual reset mechanisms which may be also used for manual release
- H01H71/501—Means for breaking welded contacts; Indicating contact welding or other malfunction of the circuit breaker
Landscapes
- Breakers (AREA)
Abstract
ABSTRACT OF THE INVENTION
Apparatus for directly contacting the handle arm of a circuit breaker, when one or more of the moveable contacts of the circuit breaker is welded to its fixed contact, thereby preventing the operating lever from being moved to the full off position. This prevents a person from erroneously believing that an electrical circuit, connected to the circuit breaker, is de-energized when the contacts are so welded since the operating lever cannot be moved to the off position and thereby provide a false indication of the position of the contacts.
Apparatus for directly contacting the handle arm of a circuit breaker, when one or more of the moveable contacts of the circuit breaker is welded to its fixed contact, thereby preventing the operating lever from being moved to the full off position. This prevents a person from erroneously believing that an electrical circuit, connected to the circuit breaker, is de-energized when the contacts are so welded since the operating lever cannot be moved to the off position and thereby provide a false indication of the position of the contacts.
Description
20(:~4~
W.E. 54,716 ELECTRICAL CIRCUIT BREAXER
HANDLE LOCKING APPARATUS
5Background of the Invention 1. Field of the Invention This invention relates to electrical circuit breakers and, more particularly, to electrical circuit breakers which incorporate apparatus for directly contacting the handle arm of the breaker and , restricting the travel of the operating handle when the contacts of the circuit breaker are closed.
W.E. 54,716 ELECTRICAL CIRCUIT BREAXER
HANDLE LOCKING APPARATUS
5Background of the Invention 1. Field of the Invention This invention relates to electrical circuit breakers and, more particularly, to electrical circuit breakers which incorporate apparatus for directly contacting the handle arm of the breaker and , restricting the travel of the operating handle when the contacts of the circuit breaker are closed.
2. Description of the Prior Art Electrical circuit breakers have been employed for many years. Typically, they are serially connected between an electrical power source and an electrical circuit to interrupt the flow of current in the electrical circuit when the electrical circuit is experiencing an overcurrent condition wherein the . . .
` -` 2004181 W.E. 54,716 circuit is carrying excessive currents for prescribed periods of time. An operating mechanism is employed to trip open separable electrical contacts within the circuit breaker during such overcurrent conditions thereby stopping current flow through the electrical circuit. Some operating mechanisms employ a dual tripping system for opening the contacts of the circuit breaker during such overcurrent conditions.
One system employs a heater which is electrically connected in series with the electrical circuit. The heater has known electrical resistance properties and, hence, current flow through it generates heat which elevates the temperature of the heater above the temperature of the ambiant air. Some of this heat is conducted to a mechanically connected bimetal strip. The bimetal strip is constructed of two different, generally, flat pieces of metal, with different temperature expansion coefficients, which are glued or otherwise attached together. Since each of the two metal strips expands to a different length when heated as the result of electrical current flow ` ` X~)0~
` -` 2004181 W.E. 54,716 circuit is carrying excessive currents for prescribed periods of time. An operating mechanism is employed to trip open separable electrical contacts within the circuit breaker during such overcurrent conditions thereby stopping current flow through the electrical circuit. Some operating mechanisms employ a dual tripping system for opening the contacts of the circuit breaker during such overcurrent conditions.
One system employs a heater which is electrically connected in series with the electrical circuit. The heater has known electrical resistance properties and, hence, current flow through it generates heat which elevates the temperature of the heater above the temperature of the ambiant air. Some of this heat is conducted to a mechanically connected bimetal strip. The bimetal strip is constructed of two different, generally, flat pieces of metal, with different temperature expansion coefficients, which are glued or otherwise attached together. Since each of the two metal strips expands to a different length when heated as the result of electrical current flow ` ` X~)0~
~ W.E. 54,716 through the heater, the strip bends out of the linear configuration which it assumes when no current is flowing.
The degree of bending is a function of the temperature of the strip. Since the temperature of the strip is related to the magnitude of current flswing through the heater and serially connected electrical circuit, the degree of bending is, therefore, a function of the magnitude of current flowing through the electrical circuit.
The circuit breaker employs a trip mechanism to trip open the contacts of the circuit breaker, thereby stopping the flow of current through the circuit breaker and the electrical circuit, when the trip bar of the trip mechanism is rotated through a predetermined angle. The bimetal strip bends and rotates the trip bar through such a predetermined angle when the current flowing through the circuit breaker, and hence the electrical circuit, exceeds predetermined levels for prescribed periods of time.
Another device used to trip the circuit breaker during overcurrent conditions employs an electromagnet. The electromagnet is electrically .
200~8~
The degree of bending is a function of the temperature of the strip. Since the temperature of the strip is related to the magnitude of current flswing through the heater and serially connected electrical circuit, the degree of bending is, therefore, a function of the magnitude of current flowing through the electrical circuit.
The circuit breaker employs a trip mechanism to trip open the contacts of the circuit breaker, thereby stopping the flow of current through the circuit breaker and the electrical circuit, when the trip bar of the trip mechanism is rotated through a predetermined angle. The bimetal strip bends and rotates the trip bar through such a predetermined angle when the current flowing through the circuit breaker, and hence the electrical circuit, exceeds predetermined levels for prescribed periods of time.
Another device used to trip the circuit breaker during overcurrent conditions employs an electromagnet. The electromagnet is electrically .
200~8~
W.E. 54,716 connected in series with the electrical circuit, as is the heater. When the magnitude current flowing through the electrical circuit, and hence the electromagnet, exceeds a predetermined limit, a moveable member of the electromagnet, which is ~_ mechanically connected to the trip bar of the circuit breaker, rotates due to the magnetic forces generated by the electrical current and trips the breaker open.
The flow of current in the electrical circuit is, thereby, terminated.
`Typically, the bimetal strip is employed to trip the circuit breaker open after a predetermined period of time has elapsed after the commencement of a relatively small overcurrent condition. Typically, the bimetal strip is designed to trip the circuit breaker when the current flowing through the electrical circuit exceeds the rating of the circuit breaker by between 10 percent and 500 percent for a predetermined period of time. The electromagnet trip mechanism, on the other hand, is designed to trip the breaker open at the onset of an overcurrent condition which exceeds the rating of the breaker by more than 500 percent.
20041~1.
PATENT
W.E. 54,716 The operating mechanisms of circuit breakers also employ a manual operating device which enables a person to open and close the contacts of the circuit breaker as desired. Such manual operating devices are rendered inactive when~the circuit breaker has tripped due to an electrical circuit overcurrent condition, thereby preventing the person from reclosing the contacts of the circuit breaker until the overcurrent condition has subsided.
Current flow through the circuit breaker, and hence the serially connected electrical circuit, is controlled by the separable contacts. The separable contacts include a moveable member which is mechanically connected to the operating mechanism of the circuit breaker and a fixed member which is mechanically connected to the circuit breaker housing.
The moveable member moves a moveable contact in engagement with a fixed contact on the fixed member to close the electrical circuit and separates the moveable contact from the fixed contact to open the electrical circuit. One pair of contacts is provided for each pole, or phase, of the breaker.
W.E. 54,716 The operating mechanism is designed to rapidly move the separable contacts between the open and closed positions thereby preventing the moveable contact from stopping at any position which is intermediate the fully open or fully closed position.
This accomplishes two purposes. First, when the contacts are quickly closed, the resultant force with which the moveable contact strikes the fixed contact helps to ensure good electrical conduction since impurities which may become positioned between the contacts, such as dust and dirt, are dislodged.
Second, when the contacts are quickly opened, the opportunity for electrical arcing between the fixed contact and the moveable contact is minimized since the contacts are quickly separated through an arc suppressor by a distance which is sufficient to suppress the arcing and open the electrical circuit.
The moveable electrical contact is designed not only to strike the fixed contact, when closed, but also to slide across the surface of the fixed contact.
This sliding action further aids in dislodging impurities from between the contacts.
200~
W.E. 54,716 Despite the aforementioned features which are built into the circuit breaker to ensure good electrical conduction, small amounts of debris may, nevertheless, become interposed between the fixed contact and the moveable contact. Under such circumstances, the possibility exists that the fixed member of the contact will weld to the moveable contact thereby preventing the circuit breaker from opening either during an overcurrent condition or during manual operation. Contact welding may also occur if the circuit breaker mechanically fails, thereby reducing the force applied by the moveable contact to the fixed contact.
The circuit breaker includes a pivoting lever, which projects through an opening formed in its housing, for manual operation. The lever may assume one of three positions during normal operation of the circuit breaker. In the on position, the lever is positioned at one end of its permissible travel. When the operating lever is moved to this position, and the breaker is not tripped, the contacts of the circuit breaker close thereby allowing electrical current to flow from the current source to the electrical ` " ~004~
W.E. 54,716 circuit. At the opposite end of travel of the lever is the off or reset position. When the lever is moved to that position, the contacts of the clrcuit breaker open, except as described below, thereby interrupting the current flow through the circuit breaker.
A third position is the tripped position which is approximately midway between the on position and the off position. The lever automatically assumes this position when either the bimetal or electromagnet overcurrent protection has automatically tripped the breaker or when a manual trip button, located within an opening formed in the housing of the circuit breaker, is pressed. Once the circuit breaker has been tripped, the electrical contacts cannot be reclosed until the operating lever is first moved to the reset position and then back to the on position.
In a multi-pole circuit breaker, all of the moveable contacts are mechanically connected together so that they move in unison and are, hence, either all open or all closed.
... .
200~18~
W.E. 54,716 As previously described, it is possible for one or more of the contacts of the circuit breaker to weld closed thereby preventing all of the contacts for all of the poles from opening when the circuit breaker is tripped or when the lever is moved to the off position. However, the operating lever of the circuit breaker may still be manually moved to the off position even when the electrical contacts are welded closed and, hence, the electrical circuit is energized.
This is because the moveable contacts are mechanically connected to the operating lever through biasing springs. By applying a force of enough magnitude, the lever may be moved to the off position by overcoming the biasing force of the springs.
This can create a dangerous condition if, for example, a person were to move the operating lever to the off position, thereby believing that the electrical contacts are open and that the electrical circuit is, therefore, deenergized when in actuality - 200~81.
PATENT
W.E. 54,716 it is not. A person could attempt to manually access energized portions of the circuit and unexpectedly receive an electrical shock. The present invention reduces the risk of such occurrence by providing apparatus which mechanically limits the travel of the operating lever so that it may not be moved fully to the off position when the electrical contacts are closed, such as when they are welded.
Summary of the Invention The present invention provides apparatus for limiting the travel of the operating lever of an electrical circuit breaker to a predetermined position which includes electrical contacts which may assume a closed position and an open position, an operating lever which may be moved between an on position and an off position and a handle arm which moves in unison with the operating lever. The apparatus includes lever lock apparatus for directly contacting the handle arm of the electrical circuit breaker and limiting the travel of the operating lever to a predetermined position intermediate the on position and the off position when the lever is moved from the 200~81.
W.E. 54,716 on position toward the off position and the electrical contacts of the electrical circuit breaker are in the closed position.
Also provided is electrical circuit overcurrent protection apparatus which includes electrical contact apparatus capable of assuming an open position for interrupting the flow of electrical current in the electrical circuit and capable of assuming a closed position for allowing electrical current to flow in the electrical circuit. A handle arm is connected to the electrical contact apparatus for manually moving the electrical contact apparatus between the open position and the closed position. An operating lever is connected to the handle arm, which is capable of assuming an on position and an off position, for moving the handle arm. Overcurrent protection apparatus, mechanically connected to the electrical contact apparatus, is provided for moving the electrical contact apparatus to the open position when the electrical current in the electrical circuit exceeds predetermined values for predetermined periods of time and lever lock apparatus is provided ~nd relatively positioned with respect to the handle arm -- xoo4la~.
12 PAT~NT
W.E. 5~,716 for directly contacting the handle arm and limiting the travel of the operating lever to a predetermined position intermediate the on position and the off position when the operating lever is manually moved froin the on position toward the off position and the ~, electrical contact apparatus is in the closed position.
Brief Description of the 3rawin~
The ini7ention may b,- better unders'ood and further advantages and ~ses thereof are readily apparent, when considered ln view of the following detailed description of the p.eferred embodiment taken with the accompanying drawings in \~hich:
Fig. 1 is a sectional side ele~vational view of an electrical circuit breaker which incorporates the apparatus of the present invention;
Fig. 2 is a front elevational view of the circuit breaker of Fig. 1;
Fig. 3 is a rear elevational view of the circuit breaker of Fig. l;
Fig. 4 is a perspective view of the circuit breaker of Fig. 1:
2(1041~31.
W.E. 54,716 Fig. 5 is a sectional side elevation view of the circuit breaker of Fig. l;
Fig. 6 is an exploded view of the arc suppressor of Fig. 4;
S Fig. 7 is a sectional view of the apparatus of Fig. 1; and Fig. 8 is a perspective view of the crossbar of Fig. 1.
Detailed Description of the Preferred Embodiment Figs. 1 through 8 show a circuit breaker which incorporates the preferred embodiment of the present invention. Circuit breaker 2 includes housing 4 which is, preferably, molded plastic. Housing 4 comprises base 6 and removeable cover 8. Removeable cover 8 is mechanically attached to base 6 through the use of screws (not shown) which engage base 6 through openings 10.
Circuit breaker 2 employs contact arms 12, 14 and 16 which open and close the three current paths, or poles, of circuit breaker 2. Contact arms 12, 14 and 16 are mechanically connected to crossbar 18 so that they move in unison and are either all in the closed position or all in the open position.
200~
W.E. 54,716 Contact arms 12, 14 and 16 support moveable contacts 17, 19 and 23, respectively. Moveable contact 19 is designed to mechanically contact fixed contact 20 for closing the electrical current path through center pole 24. Contact 20 is supported by support 21.
- Similar fixed contacts (not shown) are provided for opening and closing the electrical current paths through left pole 26 and right pole 28. The operation of circuit breaker 2 will be described with respect to center pole 24. Poles 26 and 28 employ apparatus identical to that of pole 24.
Electrical conductor 30 is engaged by clamp 32 which is raised and lowered by bolt 34. Electrical conductor 30 supplies the electricity which will be transmitted through center pole 24. Contact 36 is held in tight engagement with electrical conductor 30 by the force exerted by clamp 32. Current flows from conductor 30, through terminal 36 and line copper 60, which is electrically connected to fixed contact 20.
Fixed contact 20 is mechanically attached to support 21. Current then flows from fixed contact 20, through mo~eable contact 19, contact arm 14 and conductor 52 200~
PATENT
W.E. 54,716 to bimetal 48. Conductor 52 is, preferably, a braided copper conductor which can be bent repeatedly without breaking.
Bimetal 48 then conducts the current to electromagnet assembly 40. Electromagnet assembly 40 ~, includes fixed members 42 and 43, spring 47 and pivoting member 44. As electrical current flows through electromagnet 40, a magnetic flux is generated between magnet frame 43 and pivoting member 44 which applies a force on pivoting member 44 in the direction of arrow 46.
The electrical current then flows through heater 38, which is electrically connected to bimetal 48 and to terminal 37 which is connected to the electrical circuit. Heater 38 and bimetal 48 both have known electrical resistance properties which cause heat to be generated when electrical current flows therethrough. The heat generated in heater 38 and bimetal 48 elevates the temperature of bimetal 48 causing it to bend in the direction of arrow 50.
When contact arm 14 is in the closed position, as shown in Fig. 1, moveable contact 19 is pressed in tight engagemPnt with fixed contact 20 200~
W.E. 54,716 through force exerted by springs 56 and 58. The electrical current, originating from conductor 30, can flow through pole 24 when contact l9 is so engaged with contact 20.
When contact arm 14 is raised to the open position, as shown in Figs. 5 and 7, no current can flow through center pole 24 and the serially connected electrical circuit is de-energized. Since contact arms 12 and 16 move in unison with contact arm 14, poles 26 and 28 also stop electrical current flow therethrough.
As shown by the solid lines in Fig. l, operating lever 62 is in the on position. Handle arm 75 is mechanically connected to lever 62 and pivot pin lO0 and is positioned against stop member 64. Springs 56 and 58 are in tension and exert a force on lower link 66 through pivot pin lO0 which is both upward and to the left. Lower link 66 is mechanically connected to both crossbar 18 and contact arm 14. The upward and leEtward force exerted on lower link 66 causes moveable contact l9 to be secured in tight engagement with fixed contact 20.
`` 200~81.
W.E. 54,716 Fig. 7 shows circuit breaker 2 in the ope~
position with contact 19 separated from contact 20 and operating lever 62 in the off position. Moveable contacts 17 and 23 are also separated from their respective fixed contacts since they move in unison ~_ with moveable contact 19.
As described above, any one of moveable contacts 17, 19 and 23 may become welded in the closed position to its respective fixed contact. Under this condition contact arms 12, 14 and 16 and lower link 66 will be positioned as shown in Fig. 1. Springs 56 and 58 will apply a biasing force on operating lever 62 moving it to the on position. However, the biasing force of springs 56 and 58 may be overcome by applying a suitable force to lever 62 thereby allowing it to be moved to the off position. The present invention prevents this from occurring.
The present invention includes lock 70, cam 72 and locking surface 74. When moveable contacts 17, 19 and 23 are in the closed position, crossbar 18 and cam 72 assume the position shown in Fig. 1. Cam 72 is positioned to elevate lock 70, which is held in place by plate 71, to the position shown in Fig. 1.
200~
W.E. 54,716 If operating lever 62 were then moved toward the off position, as shown in shadow in Fig. 1, locking surface 74 of handle arm 75 would engage projecting member 76 of lock 70 thereby preventing handle arm 75 and, thus, operating lever 62 from ~_ advancing to the full off position as shown in Fig. 7.
Lever 62 would move back to the on position once the manual force overcoming the biasing force of springs 56 and 58 were removed.
10The present invention, therefore, provides ` the dual advantages of preventing operating lever 62 from falsely assuming the off position when the contacts of circuit breaker 2 are closed and, hence, the associated electrical circuit energized, and moving operating lever 62 to the on position to provide a positive, visual indication of the closed contact condition.
If operating lever 62 would be moved from the on position toward the off position when none of moveable contacts 17, 19 and 23 are welded to their respective fixed contacts, springs 56 and 58 would exert a force on lower link 66 which is both upward and to the right causing it to pivot about crossbar 18 200~
W.E. 54,716 in the direction of arc 78. As operating lever 62 is further moved toward the off position, and before it reaches the position shown in shadow on Fig. 1, the force exerted by springs 56 and 58 on lower link 66 will cause crossbar 18 and contact arms 12, 14 and 16 to quickly pivot in the direction of arrow 78 thereby opening the contact of circuit breaker 2.
As crossbar 18 rotates in the direction of arrow 78, cam 72 is rotated out of contact with lock 70 allowing lock 70 to pivot downward to the position shown in Fig. 7. Projecting member 76 is, thus, rotated to a position where it cannot engage locking surface 74 thereby allowing operating lever 62 to be further advanced to the full off position as shown in Fig. 7.
The apparatus of the present invention also functions effectively if circuit breaker 2 is tripped open by the bimetal or electromagnet overcurrent protection devices. If the magnitude of current flowing through any pole of circuit breaker 2 exceeds the rating of breaker 2 by between 10 percent and 500 percent for a prescribed period of time, end 80 of ZOO~
PATENT
W.E. 54,716 bimetal 48 will move in the direction of arrow 50 and press against end 82 of trip bar 84. That in turn causes trip bar 84 to pivot about arc 86.
Similarly, if the magnitude of current flowing through circuit breaker 2 exceeds the rating of breaker 2 by more than 500 percent, pivoting member 44 will immediately move under the influence of the magnetic force generated by electromagnet assembly 40 in the direction of arrow 46. Pivoting member 44 is mechanically attached to trip bar 84. When pivoting member 44 moves in the direction of arrow 46, trip bar 84 pivots about arc 86. Therefore, when either the bimetal overcurrent protection or the electromagnet overcurrent protection detects an overcurrent condition, trip bar 84 is pivoted about arc 86.
Trip bar 84 is mechanically connected to latch 88. Latch 88 is normally biased by spring 90 in the direction of arrow 92. However, both bimetal 48 and pivoting member 44 can exert sufficient force on trip bar 84 to overcome the biasing force of spring 90, under overcurrent conditions, to move latch 88 in the direction of arrow 94.
200418~
W.E. 54,716 As shown in Fig. 1, a portion of cradle 96 projects through opening 98 which is formed in latch 88. The portion of cradle 96 which projects through opening 98 hooks onto latch 88 and prevents cradle 96 from moving under the biasing force which spring 56 ~_ applies to cradle 96 through pivot pin 100.
Since cradle 96 is mechanically connected to pivot pin 100 and pivot pin 100 is mechanically connected to contact arms 12, i4 and 16, cradle 96 prevents pin 100, and parts mechanically attached thereto, from moving upward under the influence of the biasing forces of springs 56 and 58. However, when latch 88 is moved in the direction of arrow 94 by trip bar 84, latch 88 becomes disengaged from cradle 96 thereby causing pin 100, cradle 96, lower link 66 and contact arms 12, 14 and 16 to move upward. Also, crossbar 18 moves in the direction of arrow 78 due to the biasing forces of springs 56 and 58. Such upward motion of contact arms 12, 14 and 16 separates moveable contacts 17, 19 and 23 from their respective fixed contacts thereby opening all three poles of circuit breaker 2.
Z00~
W.E. 54,716 If, however, breaker 2 is tripped when one of the moveable contacts is welded to its respective fixed contact, contact arms 12, 14 and 16 cannot be raised and, therefore, crossbar 18 will not rotate out of the position shown in Fig. 1. Lock 70 will be _ elevated, as shown in Fig. 1, and contact locking surface 74 of handle arm 75 if an attempt is made to move operating lever 62 to the off position.
Therefore, the present invention prevents operating lever 62 from being moved to the full off position anytime contacts 17, 19 and 23 are closed.
When circuit breaker 2 is tripped, operating lever 62 moves from the on position, as shown in Fig.
1, to an intermediate position approximately half way between the on position and the off position. This provides a visual indication that circuit breaker 2 has been tripped by an overcurrent condition. Circuit breaker 2 is reset by moving operating lever 62 to the reset position thereby reengaging cradle 96 with latch 88. Such resetting can occur only if the contacts of the breaker are opened since the apparatus of the present invention prevents lever 62 from being moved to the reset position when the contacts are closed.
200~
W.E. 54,716 Operating lever 62 is then moved to the on position thereby pivoting contacts arms 12, 14 and 16 downward so that moveable contacts 17, 19 and 23 are in contact with their respective fixed contacts, closing all three poles of breaker 2.
Arc suppressor 102 includes a plurality of U-shaped plates 104 which are relatively positioned by insulating members 106, 108 and 110. Arc suppressor 102 quickly extinguishes any arc formed as the result of the moveable contacts being separated from their respective fixed contacts. Two additional arc suppressors (not shown) are provided for the other two poles of breaker 2.
Manual trip button 112 is provided to allow for the manual tripping of breaker 2. When button 112 is depressed it exerts a force through a mechanical linkage (not shownj which rotates trip bar 84 through a sufficient angle to trip breaker 2.
Thus, it may be seen that the apparatus of the present invention provides an effective means for preventing the operating lever of the circuit breaker fro~ assuming the full off position, when one or more of the moveable contacts of the circuit breaker is 20041~1 W.E. 54,716 welded to is respective fixed contact and for providing a positive visual indication that the contacts of the breaker are closed.
It may not be appreciated that, for purposes of illustration, certain optional items, such as _ particular terminal equipment, has been shown. Such optional items are not mandatory for the operation of the present invention and may be deleted or modified without compromising the effectiveness of the invention.
Whereas particular embodiments of the invention have been described for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details may be made without departing from the invention as defined in the appended claims.
The flow of current in the electrical circuit is, thereby, terminated.
`Typically, the bimetal strip is employed to trip the circuit breaker open after a predetermined period of time has elapsed after the commencement of a relatively small overcurrent condition. Typically, the bimetal strip is designed to trip the circuit breaker when the current flowing through the electrical circuit exceeds the rating of the circuit breaker by between 10 percent and 500 percent for a predetermined period of time. The electromagnet trip mechanism, on the other hand, is designed to trip the breaker open at the onset of an overcurrent condition which exceeds the rating of the breaker by more than 500 percent.
20041~1.
PATENT
W.E. 54,716 The operating mechanisms of circuit breakers also employ a manual operating device which enables a person to open and close the contacts of the circuit breaker as desired. Such manual operating devices are rendered inactive when~the circuit breaker has tripped due to an electrical circuit overcurrent condition, thereby preventing the person from reclosing the contacts of the circuit breaker until the overcurrent condition has subsided.
Current flow through the circuit breaker, and hence the serially connected electrical circuit, is controlled by the separable contacts. The separable contacts include a moveable member which is mechanically connected to the operating mechanism of the circuit breaker and a fixed member which is mechanically connected to the circuit breaker housing.
The moveable member moves a moveable contact in engagement with a fixed contact on the fixed member to close the electrical circuit and separates the moveable contact from the fixed contact to open the electrical circuit. One pair of contacts is provided for each pole, or phase, of the breaker.
W.E. 54,716 The operating mechanism is designed to rapidly move the separable contacts between the open and closed positions thereby preventing the moveable contact from stopping at any position which is intermediate the fully open or fully closed position.
This accomplishes two purposes. First, when the contacts are quickly closed, the resultant force with which the moveable contact strikes the fixed contact helps to ensure good electrical conduction since impurities which may become positioned between the contacts, such as dust and dirt, are dislodged.
Second, when the contacts are quickly opened, the opportunity for electrical arcing between the fixed contact and the moveable contact is minimized since the contacts are quickly separated through an arc suppressor by a distance which is sufficient to suppress the arcing and open the electrical circuit.
The moveable electrical contact is designed not only to strike the fixed contact, when closed, but also to slide across the surface of the fixed contact.
This sliding action further aids in dislodging impurities from between the contacts.
200~
W.E. 54,716 Despite the aforementioned features which are built into the circuit breaker to ensure good electrical conduction, small amounts of debris may, nevertheless, become interposed between the fixed contact and the moveable contact. Under such circumstances, the possibility exists that the fixed member of the contact will weld to the moveable contact thereby preventing the circuit breaker from opening either during an overcurrent condition or during manual operation. Contact welding may also occur if the circuit breaker mechanically fails, thereby reducing the force applied by the moveable contact to the fixed contact.
The circuit breaker includes a pivoting lever, which projects through an opening formed in its housing, for manual operation. The lever may assume one of three positions during normal operation of the circuit breaker. In the on position, the lever is positioned at one end of its permissible travel. When the operating lever is moved to this position, and the breaker is not tripped, the contacts of the circuit breaker close thereby allowing electrical current to flow from the current source to the electrical ` " ~004~
W.E. 54,716 circuit. At the opposite end of travel of the lever is the off or reset position. When the lever is moved to that position, the contacts of the clrcuit breaker open, except as described below, thereby interrupting the current flow through the circuit breaker.
A third position is the tripped position which is approximately midway between the on position and the off position. The lever automatically assumes this position when either the bimetal or electromagnet overcurrent protection has automatically tripped the breaker or when a manual trip button, located within an opening formed in the housing of the circuit breaker, is pressed. Once the circuit breaker has been tripped, the electrical contacts cannot be reclosed until the operating lever is first moved to the reset position and then back to the on position.
In a multi-pole circuit breaker, all of the moveable contacts are mechanically connected together so that they move in unison and are, hence, either all open or all closed.
... .
200~18~
W.E. 54,716 As previously described, it is possible for one or more of the contacts of the circuit breaker to weld closed thereby preventing all of the contacts for all of the poles from opening when the circuit breaker is tripped or when the lever is moved to the off position. However, the operating lever of the circuit breaker may still be manually moved to the off position even when the electrical contacts are welded closed and, hence, the electrical circuit is energized.
This is because the moveable contacts are mechanically connected to the operating lever through biasing springs. By applying a force of enough magnitude, the lever may be moved to the off position by overcoming the biasing force of the springs.
This can create a dangerous condition if, for example, a person were to move the operating lever to the off position, thereby believing that the electrical contacts are open and that the electrical circuit is, therefore, deenergized when in actuality - 200~81.
PATENT
W.E. 54,716 it is not. A person could attempt to manually access energized portions of the circuit and unexpectedly receive an electrical shock. The present invention reduces the risk of such occurrence by providing apparatus which mechanically limits the travel of the operating lever so that it may not be moved fully to the off position when the electrical contacts are closed, such as when they are welded.
Summary of the Invention The present invention provides apparatus for limiting the travel of the operating lever of an electrical circuit breaker to a predetermined position which includes electrical contacts which may assume a closed position and an open position, an operating lever which may be moved between an on position and an off position and a handle arm which moves in unison with the operating lever. The apparatus includes lever lock apparatus for directly contacting the handle arm of the electrical circuit breaker and limiting the travel of the operating lever to a predetermined position intermediate the on position and the off position when the lever is moved from the 200~81.
W.E. 54,716 on position toward the off position and the electrical contacts of the electrical circuit breaker are in the closed position.
Also provided is electrical circuit overcurrent protection apparatus which includes electrical contact apparatus capable of assuming an open position for interrupting the flow of electrical current in the electrical circuit and capable of assuming a closed position for allowing electrical current to flow in the electrical circuit. A handle arm is connected to the electrical contact apparatus for manually moving the electrical contact apparatus between the open position and the closed position. An operating lever is connected to the handle arm, which is capable of assuming an on position and an off position, for moving the handle arm. Overcurrent protection apparatus, mechanically connected to the electrical contact apparatus, is provided for moving the electrical contact apparatus to the open position when the electrical current in the electrical circuit exceeds predetermined values for predetermined periods of time and lever lock apparatus is provided ~nd relatively positioned with respect to the handle arm -- xoo4la~.
12 PAT~NT
W.E. 5~,716 for directly contacting the handle arm and limiting the travel of the operating lever to a predetermined position intermediate the on position and the off position when the operating lever is manually moved froin the on position toward the off position and the ~, electrical contact apparatus is in the closed position.
Brief Description of the 3rawin~
The ini7ention may b,- better unders'ood and further advantages and ~ses thereof are readily apparent, when considered ln view of the following detailed description of the p.eferred embodiment taken with the accompanying drawings in \~hich:
Fig. 1 is a sectional side ele~vational view of an electrical circuit breaker which incorporates the apparatus of the present invention;
Fig. 2 is a front elevational view of the circuit breaker of Fig. 1;
Fig. 3 is a rear elevational view of the circuit breaker of Fig. l;
Fig. 4 is a perspective view of the circuit breaker of Fig. 1:
2(1041~31.
W.E. 54,716 Fig. 5 is a sectional side elevation view of the circuit breaker of Fig. l;
Fig. 6 is an exploded view of the arc suppressor of Fig. 4;
S Fig. 7 is a sectional view of the apparatus of Fig. 1; and Fig. 8 is a perspective view of the crossbar of Fig. 1.
Detailed Description of the Preferred Embodiment Figs. 1 through 8 show a circuit breaker which incorporates the preferred embodiment of the present invention. Circuit breaker 2 includes housing 4 which is, preferably, molded plastic. Housing 4 comprises base 6 and removeable cover 8. Removeable cover 8 is mechanically attached to base 6 through the use of screws (not shown) which engage base 6 through openings 10.
Circuit breaker 2 employs contact arms 12, 14 and 16 which open and close the three current paths, or poles, of circuit breaker 2. Contact arms 12, 14 and 16 are mechanically connected to crossbar 18 so that they move in unison and are either all in the closed position or all in the open position.
200~
W.E. 54,716 Contact arms 12, 14 and 16 support moveable contacts 17, 19 and 23, respectively. Moveable contact 19 is designed to mechanically contact fixed contact 20 for closing the electrical current path through center pole 24. Contact 20 is supported by support 21.
- Similar fixed contacts (not shown) are provided for opening and closing the electrical current paths through left pole 26 and right pole 28. The operation of circuit breaker 2 will be described with respect to center pole 24. Poles 26 and 28 employ apparatus identical to that of pole 24.
Electrical conductor 30 is engaged by clamp 32 which is raised and lowered by bolt 34. Electrical conductor 30 supplies the electricity which will be transmitted through center pole 24. Contact 36 is held in tight engagement with electrical conductor 30 by the force exerted by clamp 32. Current flows from conductor 30, through terminal 36 and line copper 60, which is electrically connected to fixed contact 20.
Fixed contact 20 is mechanically attached to support 21. Current then flows from fixed contact 20, through mo~eable contact 19, contact arm 14 and conductor 52 200~
PATENT
W.E. 54,716 to bimetal 48. Conductor 52 is, preferably, a braided copper conductor which can be bent repeatedly without breaking.
Bimetal 48 then conducts the current to electromagnet assembly 40. Electromagnet assembly 40 ~, includes fixed members 42 and 43, spring 47 and pivoting member 44. As electrical current flows through electromagnet 40, a magnetic flux is generated between magnet frame 43 and pivoting member 44 which applies a force on pivoting member 44 in the direction of arrow 46.
The electrical current then flows through heater 38, which is electrically connected to bimetal 48 and to terminal 37 which is connected to the electrical circuit. Heater 38 and bimetal 48 both have known electrical resistance properties which cause heat to be generated when electrical current flows therethrough. The heat generated in heater 38 and bimetal 48 elevates the temperature of bimetal 48 causing it to bend in the direction of arrow 50.
When contact arm 14 is in the closed position, as shown in Fig. 1, moveable contact 19 is pressed in tight engagemPnt with fixed contact 20 200~
W.E. 54,716 through force exerted by springs 56 and 58. The electrical current, originating from conductor 30, can flow through pole 24 when contact l9 is so engaged with contact 20.
When contact arm 14 is raised to the open position, as shown in Figs. 5 and 7, no current can flow through center pole 24 and the serially connected electrical circuit is de-energized. Since contact arms 12 and 16 move in unison with contact arm 14, poles 26 and 28 also stop electrical current flow therethrough.
As shown by the solid lines in Fig. l, operating lever 62 is in the on position. Handle arm 75 is mechanically connected to lever 62 and pivot pin lO0 and is positioned against stop member 64. Springs 56 and 58 are in tension and exert a force on lower link 66 through pivot pin lO0 which is both upward and to the left. Lower link 66 is mechanically connected to both crossbar 18 and contact arm 14. The upward and leEtward force exerted on lower link 66 causes moveable contact l9 to be secured in tight engagement with fixed contact 20.
`` 200~81.
W.E. 54,716 Fig. 7 shows circuit breaker 2 in the ope~
position with contact 19 separated from contact 20 and operating lever 62 in the off position. Moveable contacts 17 and 23 are also separated from their respective fixed contacts since they move in unison ~_ with moveable contact 19.
As described above, any one of moveable contacts 17, 19 and 23 may become welded in the closed position to its respective fixed contact. Under this condition contact arms 12, 14 and 16 and lower link 66 will be positioned as shown in Fig. 1. Springs 56 and 58 will apply a biasing force on operating lever 62 moving it to the on position. However, the biasing force of springs 56 and 58 may be overcome by applying a suitable force to lever 62 thereby allowing it to be moved to the off position. The present invention prevents this from occurring.
The present invention includes lock 70, cam 72 and locking surface 74. When moveable contacts 17, 19 and 23 are in the closed position, crossbar 18 and cam 72 assume the position shown in Fig. 1. Cam 72 is positioned to elevate lock 70, which is held in place by plate 71, to the position shown in Fig. 1.
200~
W.E. 54,716 If operating lever 62 were then moved toward the off position, as shown in shadow in Fig. 1, locking surface 74 of handle arm 75 would engage projecting member 76 of lock 70 thereby preventing handle arm 75 and, thus, operating lever 62 from ~_ advancing to the full off position as shown in Fig. 7.
Lever 62 would move back to the on position once the manual force overcoming the biasing force of springs 56 and 58 were removed.
10The present invention, therefore, provides ` the dual advantages of preventing operating lever 62 from falsely assuming the off position when the contacts of circuit breaker 2 are closed and, hence, the associated electrical circuit energized, and moving operating lever 62 to the on position to provide a positive, visual indication of the closed contact condition.
If operating lever 62 would be moved from the on position toward the off position when none of moveable contacts 17, 19 and 23 are welded to their respective fixed contacts, springs 56 and 58 would exert a force on lower link 66 which is both upward and to the right causing it to pivot about crossbar 18 200~
W.E. 54,716 in the direction of arc 78. As operating lever 62 is further moved toward the off position, and before it reaches the position shown in shadow on Fig. 1, the force exerted by springs 56 and 58 on lower link 66 will cause crossbar 18 and contact arms 12, 14 and 16 to quickly pivot in the direction of arrow 78 thereby opening the contact of circuit breaker 2.
As crossbar 18 rotates in the direction of arrow 78, cam 72 is rotated out of contact with lock 70 allowing lock 70 to pivot downward to the position shown in Fig. 7. Projecting member 76 is, thus, rotated to a position where it cannot engage locking surface 74 thereby allowing operating lever 62 to be further advanced to the full off position as shown in Fig. 7.
The apparatus of the present invention also functions effectively if circuit breaker 2 is tripped open by the bimetal or electromagnet overcurrent protection devices. If the magnitude of current flowing through any pole of circuit breaker 2 exceeds the rating of breaker 2 by between 10 percent and 500 percent for a prescribed period of time, end 80 of ZOO~
PATENT
W.E. 54,716 bimetal 48 will move in the direction of arrow 50 and press against end 82 of trip bar 84. That in turn causes trip bar 84 to pivot about arc 86.
Similarly, if the magnitude of current flowing through circuit breaker 2 exceeds the rating of breaker 2 by more than 500 percent, pivoting member 44 will immediately move under the influence of the magnetic force generated by electromagnet assembly 40 in the direction of arrow 46. Pivoting member 44 is mechanically attached to trip bar 84. When pivoting member 44 moves in the direction of arrow 46, trip bar 84 pivots about arc 86. Therefore, when either the bimetal overcurrent protection or the electromagnet overcurrent protection detects an overcurrent condition, trip bar 84 is pivoted about arc 86.
Trip bar 84 is mechanically connected to latch 88. Latch 88 is normally biased by spring 90 in the direction of arrow 92. However, both bimetal 48 and pivoting member 44 can exert sufficient force on trip bar 84 to overcome the biasing force of spring 90, under overcurrent conditions, to move latch 88 in the direction of arrow 94.
200418~
W.E. 54,716 As shown in Fig. 1, a portion of cradle 96 projects through opening 98 which is formed in latch 88. The portion of cradle 96 which projects through opening 98 hooks onto latch 88 and prevents cradle 96 from moving under the biasing force which spring 56 ~_ applies to cradle 96 through pivot pin 100.
Since cradle 96 is mechanically connected to pivot pin 100 and pivot pin 100 is mechanically connected to contact arms 12, i4 and 16, cradle 96 prevents pin 100, and parts mechanically attached thereto, from moving upward under the influence of the biasing forces of springs 56 and 58. However, when latch 88 is moved in the direction of arrow 94 by trip bar 84, latch 88 becomes disengaged from cradle 96 thereby causing pin 100, cradle 96, lower link 66 and contact arms 12, 14 and 16 to move upward. Also, crossbar 18 moves in the direction of arrow 78 due to the biasing forces of springs 56 and 58. Such upward motion of contact arms 12, 14 and 16 separates moveable contacts 17, 19 and 23 from their respective fixed contacts thereby opening all three poles of circuit breaker 2.
Z00~
W.E. 54,716 If, however, breaker 2 is tripped when one of the moveable contacts is welded to its respective fixed contact, contact arms 12, 14 and 16 cannot be raised and, therefore, crossbar 18 will not rotate out of the position shown in Fig. 1. Lock 70 will be _ elevated, as shown in Fig. 1, and contact locking surface 74 of handle arm 75 if an attempt is made to move operating lever 62 to the off position.
Therefore, the present invention prevents operating lever 62 from being moved to the full off position anytime contacts 17, 19 and 23 are closed.
When circuit breaker 2 is tripped, operating lever 62 moves from the on position, as shown in Fig.
1, to an intermediate position approximately half way between the on position and the off position. This provides a visual indication that circuit breaker 2 has been tripped by an overcurrent condition. Circuit breaker 2 is reset by moving operating lever 62 to the reset position thereby reengaging cradle 96 with latch 88. Such resetting can occur only if the contacts of the breaker are opened since the apparatus of the present invention prevents lever 62 from being moved to the reset position when the contacts are closed.
200~
W.E. 54,716 Operating lever 62 is then moved to the on position thereby pivoting contacts arms 12, 14 and 16 downward so that moveable contacts 17, 19 and 23 are in contact with their respective fixed contacts, closing all three poles of breaker 2.
Arc suppressor 102 includes a plurality of U-shaped plates 104 which are relatively positioned by insulating members 106, 108 and 110. Arc suppressor 102 quickly extinguishes any arc formed as the result of the moveable contacts being separated from their respective fixed contacts. Two additional arc suppressors (not shown) are provided for the other two poles of breaker 2.
Manual trip button 112 is provided to allow for the manual tripping of breaker 2. When button 112 is depressed it exerts a force through a mechanical linkage (not shownj which rotates trip bar 84 through a sufficient angle to trip breaker 2.
Thus, it may be seen that the apparatus of the present invention provides an effective means for preventing the operating lever of the circuit breaker fro~ assuming the full off position, when one or more of the moveable contacts of the circuit breaker is 20041~1 W.E. 54,716 welded to is respective fixed contact and for providing a positive visual indication that the contacts of the breaker are closed.
It may not be appreciated that, for purposes of illustration, certain optional items, such as _ particular terminal equipment, has been shown. Such optional items are not mandatory for the operation of the present invention and may be deleted or modified without compromising the effectiveness of the invention.
Whereas particular embodiments of the invention have been described for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details may be made without departing from the invention as defined in the appended claims.
Claims (7)
1. Apparatus for limiting the travel of the operating lever of an electrical circuit breaker to a predetermined position which includes electrical contacts which may assume a closed position and an open position, an operating lever which may be moved between an on position and an off position and a handle arm which moves in unison with the operating lever comprising:
lever lock means for directly contacting the handle arm of the electrical circuit breaker and limiting the travel of the operating lever to a predetermined position intermediate the on position and the off position when the lever is moved from the on position toward the off position and the electrical contacts of the electrical circuit breaker are in the closed position.
lever lock means for directly contacting the handle arm of the electrical circuit breaker and limiting the travel of the operating lever to a predetermined position intermediate the on position and the off position when the lever is moved from the on position toward the off position and the electrical contacts of the electrical circuit breaker are in the closed position.
2. The apparatus of claim 1 wherein:
the electrical circuit breaker includes a support;
the handle arm includes an engagement surface; and said lever lock means includes latch means mechanically connected to the support which is adapted to assume a first position to engage said engagement surface and limit the travel of the operating lever to said predetermined position when the electrical contacts are in the closed position and which is adapted to assume a second position to allow the operating lever to travel from the on position to the off position when the electrical contacts are in the open position.
the electrical circuit breaker includes a support;
the handle arm includes an engagement surface; and said lever lock means includes latch means mechanically connected to the support which is adapted to assume a first position to engage said engagement surface and limit the travel of the operating lever to said predetermined position when the electrical contacts are in the closed position and which is adapted to assume a second position to allow the operating lever to travel from the on position to the off position when the electrical contacts are in the open position.
3. The apparatus of claim 2 wherein the electrical circuit breaker includes a crossbar mechanism which is mechanically connected to the support and which defines a cam for moving said latch means between said first position and said second position.
4. The apparatus of claim 3 wherein said engagement surface is defined by a recess in the handle arm.
5. The apparatus of claim 1 wherein apparatus is provided for automatically moving the operating lever to the on position when the electrical contacts are closed.
6. Electrical circuit overcurrent protection apparatus comprising:
electrical contact means capable of assuming an open position for interrupting the flow of electrical current in the electrical circuit and capable of assuming a closed position for allowing electrical current to flow in the electrical circuit;
handle arm means connected to said electrical contact means for manually moving said electrical contact means between said open position and said closed position;
operating lever means connected to said handle arm means and capable of assuming an on position and an off position for moving said handle arm means;
overcurrent protection means mechanically connected to said electrical contact means for moving said electrical contact means to said open position when the electrical current in the electrical circuit exceeds predetermined values for predetermined periods of time; and lever lock means relatively positioned with respect to said handle arm means for directly contacting said handle arm means and limiting the travel of said operating lever means to a predetermined position intermediate said on position and said off position when said operating lever means is manually moved from said on position toward said off position and said electrical contact means is in said closed position.
electrical contact means capable of assuming an open position for interrupting the flow of electrical current in the electrical circuit and capable of assuming a closed position for allowing electrical current to flow in the electrical circuit;
handle arm means connected to said electrical contact means for manually moving said electrical contact means between said open position and said closed position;
operating lever means connected to said handle arm means and capable of assuming an on position and an off position for moving said handle arm means;
overcurrent protection means mechanically connected to said electrical contact means for moving said electrical contact means to said open position when the electrical current in the electrical circuit exceeds predetermined values for predetermined periods of time; and lever lock means relatively positioned with respect to said handle arm means for directly contacting said handle arm means and limiting the travel of said operating lever means to a predetermined position intermediate said on position and said off position when said operating lever means is manually moved from said on position toward said off position and said electrical contact means is in said closed position.
7. The apparatus of claim 6 wherein:
said handle arm means defines a recessed engagement surface; and said lever lock means defines a pivoting latch which engages said engagement surface and limits the travel of said operating lever means to said predetermined position when said operating lever means is moved from said on position toward said off position and said electrical contact means is closed.
said handle arm means defines a recessed engagement surface; and said lever lock means defines a pivoting latch which engages said engagement surface and limits the travel of said operating lever means to said predetermined position when said operating lever means is moved from said on position toward said off position and said electrical contact means is closed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US28113588A | 1988-12-08 | 1988-12-08 | |
| US281,135 | 1988-12-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2004181A1 true CA2004181A1 (en) | 1990-06-08 |
Family
ID=23076087
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002004181A Abandoned CA2004181A1 (en) | 1988-12-08 | 1989-11-29 | Electrical circuit breaker handle locking apparatus |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPH02199734A (en) |
| CN (1) | CN1043222A (en) |
| AU (1) | AU4473389A (en) |
| BR (1) | BR8906276A (en) |
| CA (1) | CA2004181A1 (en) |
| GB (1) | GB2226451B (en) |
| ZA (1) | ZA898764B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2704354B1 (en) * | 1993-04-20 | 1995-06-23 | Merlin Gerin | CONTROL MECHANISM OF A MODULAR ELECTRIC CIRCUIT BREAKER. |
| WO1997035333A1 (en) * | 1996-03-15 | 1997-09-25 | Mitsubishi Denki Kabushiki Kaisha | Circuit breaker |
| US5910760A (en) * | 1997-05-28 | 1999-06-08 | Eaton Corporation | Circuit breaker with double rate spring |
| DE19841685C2 (en) * | 1998-09-11 | 2002-10-31 | Aeg Niederspannungstech Gmbh | switch |
| KR100914203B1 (en) * | 2007-08-10 | 2009-08-27 | 엘에스산전 주식회사 | Mold cased circuit breaker with a contact on mechanism |
| US9349560B2 (en) * | 2014-02-20 | 2016-05-24 | General Electric Company | Limiter type air circuit breaker with blow open arrangement |
| WO2016111000A1 (en) * | 2015-01-09 | 2016-07-14 | 三菱電機株式会社 | Circuit breaker |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE8023509U1 (en) * | 1980-08-29 | 1980-11-27 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Low voltage circuit breaker for locking lever |
| US4679016A (en) * | 1986-01-08 | 1987-07-07 | General Electric Company | Interchangeable mechanism for molded case circuit breaker |
| GB2215519B (en) * | 1988-03-01 | 1991-12-18 | Midland Electric Mfg Co Ltd | Circuit breaker |
-
1989
- 1989-11-16 ZA ZA898764A patent/ZA898764B/en unknown
- 1989-11-17 AU AU44733/89A patent/AU4473389A/en not_active Abandoned
- 1989-11-29 CA CA002004181A patent/CA2004181A1/en not_active Abandoned
- 1989-12-06 BR BR898906276A patent/BR8906276A/en unknown
- 1989-12-07 GB GB8927714A patent/GB2226451B/en not_active Expired - Fee Related
- 1989-12-08 JP JP1320352A patent/JPH02199734A/en active Pending
- 1989-12-08 CN CN89109122A patent/CN1043222A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2226451B (en) | 1993-07-07 |
| GB8927714D0 (en) | 1990-02-07 |
| GB2226451A (en) | 1990-06-27 |
| BR8906276A (en) | 1990-08-21 |
| ZA898764B (en) | 1990-08-29 |
| JPH02199734A (en) | 1990-08-08 |
| AU4473389A (en) | 1990-06-14 |
| CN1043222A (en) | 1990-06-20 |
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| Date | Code | Title | Description |
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| FZDE | Dead |