GB2212663A - Circuit breaker with adjustable rating selector - Google Patents

Abstract

A circuit breaker including separable contacts and a trip device for automatically opening the contacts when an overcurrent is detected comprises a manual selector having a plurality of rating positions for adjusting the level of overcurrent that will actuate the trip device. The selector includes a rotatable switch 187 which adjusts the current rating by switching a certain number of resistors 189 into circuit. An indicator disk of the selector has indicia for each rating position alignable through a viewing window 201 in a removable cover of the housing enclosing the circuit breaker. <IMAGE>

Description

CIRCUIT BREAKER WITH ADJUSTABLE RATING SELECTOR This invention relates to a circuit breaker, and in particular to an adjustable rating selector. Furthermore, the circuit breaker is of the type comprising latched stored energy mechanism releasable to effect tripping and, specifically it pertains to trip means automatically operable in response to overload conditions, which conditions are adjustably established by a rating selector switch.

Presently, molded case circuit breakers with solid-state trip units have embodied replaceable rating plugs which allow a single type of breaker to be applied for different load current ratings such as disclosed in the specifications of U.S. Patents Nos. 3,826,951 and 4,298,852. The disadvantage of such circuit breakers is that the user must stock several different plugs for each frame size. Associated with the foregoing is the fact that heretofore the rating plugs have been accessible to any unauthorized personnel.

Accordinq to the present invention, a circuit breaker having an adjustable rating selector, comprises a housing, a circuit breaker structure mounted within the housing and having a pair of separable contacts operable between open and closed positions to interrupt an electrical circuit, releasable means operable from a latched to a tripped position to automatically open the contacts, and an operating mechanism for moving the contacts between open and closed position, trip means responsive to current flow through the contacts for actuating the releasable means from the latched position to the tripped position to automatically open the contacts upon detection of overcurrent conditions, the trip means comprising a manual selector having a plurality of positions of incremental ratings for adjusting the level of overcurrent that will operate the trip means, the manual selector being located within the housing, the housing including a removable cover to enable access to the manual selector, the cover including a window and indicia for each rating position being alignable with the window, the manual selector including a rotary switch and an indicator disk, and the disk having the indicia for each rating position alignable with the window.

Conveniently, the manual selector being located within the housing which includes a removable cover to enable access to the manual selector, tne manual selector also comprising a rating position indicator having spaced indicia for each rating position, the cover including a window and the indicia for each rating position being alignable with the window, the manual selector including a rotary switch and indicator disk which disk has the indicia for each rating position alignable with the window and the rotary switch being coupled with a printed circuit board.

The advantage of the circuit breaker structure ofthis invention is that it provides an adjustable rating device having several resistors that can be switched to desired rating positions instead of a removable rating device having a single resistance for each rating. This advantage includes enclosure of the adjustable rating plug within the circuit breaker housing having a window aligned with indicia settings for each rating, whereby the rating device -is unavailable to unauthorized personnel.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a side sectional view, with parts broken away, through the center pole unit of a three-pole circuit breaker and taken along the lines I-I of Fig. 2; Figure 2 is a top plan view of the circuit breaker shown in Fig. 1; Figure 3 is an enlarged sectional view, with parts broken away, taken on the line III-III of Fig. 4; Figure 4 is a sectional view, with parts broken away, taken generally along the line IV-IV of Fig. 2; Figure 5 is an enlarged sectional view taken on the line V-V of Fig. 2, and showing the connection between the adjustable reading selector and the magnetic trip actuator; Figure 6 is a diagrammatic view illustrating the adjustable rating selector with respect to the cover of the housing; and Figure 7 is a schematic view illustrating the solid-state circuit utilized in the circuit breaker of Figs. 1 and 2.

A three-pole molded-case or insulating-housing type circuit breaker 5 (Figs. 1 and 2) and is similar to that disclosed in the specification of U.S. Patent No.

3,826,951. An insulating housing comprises a molded insulating base 11 and a molded insulated cover 13.

Suitable insulating barrier means separate the housing into three adjacent insulating compartments for housing the three pole units of the three-pole circuit breaker in a manner well known in the art. In each pole unit, two terminals 15 and 17 are provided at openings in the base 11 in proximity to the opposite ends of the housing to enable connection of the circuit breaker in an electric circuit.

In each of the three-pole unit compartments of the circuit breaker, there are two conductors 21 and 23 suitably secured to the base 11. The terminal 15 is secured to the flat under surface of the conductor 21. A stationary contact 25 is fixedly secured to the front of the conductor 21. A rigid main conductor 27 is mounted on the base 11 and connected, at one end thereof to the conductor 23. The other terminal 17 is connected to the flat undersurface of the conductor 27.

A single stored-energy type operating mechanism 29, for controlling all three pole units, is mounted in the center pole unit compartment of the circuit breaker. In addition to the stationary contact 25, there is a stationary contact 31 mounted on the conductor 21 and a stationary contact surface 33 on the conductor 23 in each pole unit of the circuit breaker. The operating mechanism 29 is operable to move a movable contact structure indicated generally at 35 between open and closed positions. The movable contact structure 35 is of the type more specifically disclosed in the specification of U.S. Patent No.

3,662,134, and comprises a plurality of main bridging contact arms 37 and an arcing contact arm 39. Each of the main bridging contact arms 37 comprises a contact surface 41 cooperable with the stationary contact surface 33 and a contact 43 cooperable with the contact 31. The arcing contact arm 39 comprises a movable contact 45 cooperable with the stationary contact 25.

The contact structure 35 is supported on a contact carrier 47 that is supported for pivotal movement about a pivot pin 49. A rigid insulating tie bar 51 extends across all three pole units and is connected to the three contact carriers 47 to simultaneously move the three contact carriers 47 between open and closed positions. The contact carrier 47, for the center pole unit, is pivotally connected to a lower toggle link 53 by means of a pivot pin 55. The lower toggle link 53 is pivotally connected to an upper toggle link 57 by means of a knee pivot pin 59. The upper toggle link 57 is pivotally connected to a releasable trip member 61 by means of a pivot pin 63. The releasable trip member 61 is supported at one end thereof for pivotal movement about a fixed pivot pin 65. The releasable trip member 61 is latched, at the other end thereof, by means of a latch structure 67.

An inverted U-shaped operating lever 69 is supported at the inner ends of the legs thereof for pivotal movement on a pair of fixed pins 71. Tension springs 73 are connected at the lower ends thereof to the knee pivot 59 and at the upper ends thereof to the bight portion of the operating lever 69. A handle structure 75 is connected to the front end of the operating lever 69 and comprises a handle 77 that extends out through an opening 79 in the front of the cover 13. The handle structure 75 comprises a shroud 81 that substantially closes the opening 79 in all positions of the handle structure 75.

In each pole unit, an arc-extinguishing structure 85, comprising a plurality of U-shaped magnetic plates 87 supported in a spaced stacked relationship. The arc-extinguishing structure 85 operates to extinguish arcs drawn between the contacts 25, 45 during opening operations in a manner well known in the art.

In each pole unit, the arcing contact arm 39 is electrically connected to the conductor 23 by means of a flexible conductor 89. In the closed position of the contacts, the circuit, through each pole unit, extends from the terminal 17 through the conductor 27, the conductor 23, the movable contact structure 35, the conductor 21, to the other terminal 15. The main bridging contact arms 37 carry most of the current in the closed position of the contacts, and the current path through these contact arms extends from the contract surfaces 33, through the contacts 41, the bridging contact members 37, the contacts 43, to the contact 31. During opening operations, the main bridging the contacts 43, 31, separate first and thereafter, the current is carried from the conductor 23 through the flexible conductor 89, the arcing contact arm 39, the arcing contact 45, and the arcing contact 25.When the arcing contact arm 39 separates, an arc is drawn between the contacts 25, 45 and extinguished in the arc-extinguishing structure 85.

The circuit breaker is shown in Fig. 1 in the open position with the releasable trip number 61 latched in the latched position shown by means of the latch mechanism 67. In order to close the circuit breaker, the handle 77 is moved in a clockwise direction from the off or open position to the on or closed position to move the operating lever 69 clockwise about the pivot 71. During this movement, the overcenter springs 73 are moved over center to erect the toggle 53, 57 to thereby pivot the movable contact structure 35 of the center pole unit in a clockwise direction about the pivot 49 to the closed position. With the three contact carriers 47 being connected for simultaneous movement by means of the tie bar 51, this movement serves to simultaneously move all three of the movable contact structures to the closed position.To manually open the circuit breaker the handle 77 is moved counterclockwise to the off or open position (Fig. 1). This moves the springs 73 over a center to cause collapse of the toggle 53, 57 to thereby move the contact structure 35 to the open position. Each of the contact carriers 47 and movable contact structure 35 moves about the associated pivot pin 49 with all of the contact carriers and movable contact structures moving about a common axis between the open and closed positions.

When the circuit breaker is in the closed position and an overload occurs in any of the three pole-units, the releasable member 61 (Fig. 3) is released, in a manner to be hereinafter described, to automatically trip the circuit breaker open. Upon release of the releasable member 61, the springs 73, which are in a charged condition, rotate the trip member 6l (Fig. 3) in a clockwise direction about the pivot 65 to cause collapse of the toggle 53, 57 to thereby move the three contact carrier 47 and movable contact structure 35 to the open position.

Upon tripping movement of the circuit breaker, the handle 77 is moved to an intermediate position in between the off and on positions to provide a visual indication that the circuit breaker has tripped open.

Following a tripping operation, it is necessary to reset and relatch the circuit breaker mechanism before the contacts can be closed. Resetting and relatching is achieved by moving the handle 77 to a position past the off position. During this movement, a pin member 91 on the member 69 engages a shoulder portion 93 on the releasable member 61, and the releasable member 61 is moved down to a position to relatch the latch structure 67 in a manner to be hereinafter described. Following relatching of the latch structure 67, when the operator releases.the handle 77, the releasable member 61 is reset and relatched (Fig.

1). Thereafter, the circuit breaker can be operated in the same manner as was hereinbefore described.

The latch structure 67 (Fig. 3) comprises a generally U-shaped support bracket 97 that is secured to the conductor 27 of the center pole unit and to the base 11 by means of a path of bolts 99. A first latch member indicated generally at 101 is mounted for pivotal movement on a pivot pin 103 that is secured between the opposite side plates of the support bracket 97. The first latch member 101 comprises a pair of spaced leg parts 105 and a bight part 107 connecting the spaced leg parts 105. A first roller 109 is supported between the leg parts 105 on a pin 111 that is secured to the spaced leg parts 105. A pair of second rollers 113 are also supported on the pin 111 on the outer sides of the spaced leg parts 105. A torsion spring 115 biases the first latch member 101 in a counterclockwise direction about the pivot pin 103.

The latch structure 67 also comprises a second latch member indicated generally at 117. The second latch member 117 comprises a pair of spaced leg parts 119 and an intermediate or bight part 121 that connects the opposite spaced leg parts 119. A pair of spaced pins 123 (Figs. 1, 3) are secured to the side plates of the supporting frame 97, and the spaced legs 119 are pivotally supported on the pins 123 to support the second latch member 117 for pivotal movement on the pins 123. The opposite legs 119 of the latch member 117 are provided with notches 127 therein for receiving the rollers 113 in a manner to be hereinafter described.

The latch structure 67 also comprises a third latch member, indicated generally at 131, that latches the second latch member 117 in the latched position seen in Fig. 1. The third latch member 131 comprises a downwardly extending leg 133, having a window opening 135 (Fig. 3) and a horizontal leg 137. The latch member 131 is supported on a support plate 139 for pivotal movement about an axis normal to the plane of the paper (Fig. 3) and indicated generally at 141. The connecting part 121 of the second latch member 117 has a small projecting part 145 that rests on a ledge in the window opening 135 to latch the second latch member in the latched position (Fig. 1). The latch structure 67 is more specifically described in U.S. Patent No. 3,808,567.

The latch structure 67 is automatically unlatched upon the occurrence of overload current conditions by means of a magnetic trip actuator indicated generally at 147 (Figs. 3, 4). The magnetic trip actuator 147 is disclosed in the specification of U.S. Patent No. 3,808,567 and comprises an armature plunger 148 that is maintained in the inoperative position by magnetic means and spring biased towards an extended or actuating position by means of a spring 149. The plunger 148 comprises a shoulder part 150 and an extension 151 that extends through an opening 152 in the latch member 131 during tripping operations.

A static circuit board indicated generally at 153 (Fig. 1) supports the components of a static trip circuit (Fig. 7) is disclosed in the specification of U.S. Patent No. 3,818,275. In each pole unit, a first current transformer indicated generally at 155 (Fig. 1) is supported around the associated conductor 27. Upon the occurrence of an overload in any of the pole units, the associated transformer 155 senses the overload and operates through the static circuit 153 to pulse the magnetic trip actuator 147 to thereby release the armature plunger 148, whereupon the spring 149 moves the armature plunger 148 from the initial position seen in Fig. 1 to an extended actuating position. This operation is disclosed in the specification of U.S. Patents Nos. 3,808,567, 3,818,275, and 3,783,423.

Upon movement of the armature plunger 148 to the extended actuating or tripping position, the shoulder part 150 engages and pivots leg 131 in a counterclockwise direction about the pivot 141 to effect a tripping operation of the circuit breaker in a manner to be hereinafter described.

The circuit breaker is shown (Fig. 1) with the releasable member 61 in the latched position. In this position of the releasable member 61, when the circuit breaker contacts are in the closed position, the toggle 53, 57 is erected and the springs 73 are in a charged condition, biasing the toggle 53, 57 toward a co-llapsed position. In this position, the charged springs 73 bias the upper toggle link 57 to bias the releasable member 61 in a clockwise direction about the pivot 65. This movement is prevented by the engagement of the free end of the releasable member 61 engaging the latch roller 109 and biasing the first latch member 101 in a counterclockwise direction about the pivot 103.This movement is limited by the engagement of the latch rollers 113 with the spaced arm portions of the second latch member 117, with the rollers 113 being disposed in the slots 127 of the spaced leg portions of the second latch member 117. The force of the operating springs 73, operating through the first latch member 101 and the second latch member 117, biases the second latch member in a counterclockwise direction about the pivot 123. Counterclockwise movement of the second latch member 117 is prevented by the engagement of the latch projection 145 (Fig. 3) with the ledge in the window opening 135 of leg 133 so that with the parts in the position seen in Fig. 1, the stored energy operating mechanism is latched and will remain latched until the releasable member 61 is released.

Upon movement of the plunger, 148 to the extended actuating or tripping position, the circuit breaker is tripped. During this movement, the shoulder 150 of the plunger 148, operating against the third latch member 131, pivots the leg 133 in a counterclockwise direction about the pivot 141, whereupon the window opening 135 of the third latch member 131 releases the projection 145 to thereby release the second latch member 117. Upon release of the second latch member 117, the springs 73 (Fig. 1) move the releasable member 61 in a clockwise direction about the pivot 65. This movement of the releasable member 61 operates through the first roller member 109 and second roller members 113 to move the first latch member 101 counterclockwise and to move the second latch member 117 counterclockwise to the unlatched tripped open position (Fig. 4).During this movement, the releasable member 61 moves to the tripped position to effect collapse of the toggle 53, 57 to trip the circuit breaker in the manner hereinbefore described.

The latch structure 67 and releasable member 61 are shown in the tripped-open position in Fg. 3. In that position the latch structure 67 is tripped by movement of the leg 133 to the tripped position, in a manner to he hereinafter described, rather than by operation of the magnetic trip actuator 147 which is still in the reset position in Fig. 3. In order to reset the circuit breaker, the releasable member 61 is moved counterclockwise by movement of the handle 77 to a resetting position past the full off position of the handle 77. During this movement, the free end of the releasable member 61 engages the bight portion 107 of the first latch member 101 to pivot the first latch member 101 in a clockwise direction about the pivot 103.Near the end of this movement, the two rollers 113 drop into the notches 127 of the second latch member 117 and a torsion spring 158 moves the second latch member 117 in a clockwise direction about the pivot 123 to the latched position (Fig. 1).

During this movement, the insulating shroud portion 81 (Fig. 1), of the operating handle structure 75, engages one arm 163 of a member 165. The member 165 is generally T-shaped in side view. The member 165 comprises a pair of arms 167 extending horizontally to the left (Fig.

3), the arm 163 extending horizontally to the right and a downwardly extending leg 169. The arms 167 are pivotally supported on the plate 139 to support the member 165 for pivotal movement about an axis 141 (Fig. 3). During resetting movement of the handle structure 75 the shroud 81, pivots the member 165 in a clockwise (Fig. 1) direction, and if the circuit breaker is tripped by operation of the trip actuator 147, the downwardly extending leg 169 (Fig. 3), engaging the projecting port 151 of the plunger 148 will move the plunger 148 against the bias of the spring 151 back to the reset and relatched position.

As the plunger 148 is moved back to the reset position, a spring 160 (Figs. 3, 4) operating on the leg 137, biases the leg 133 in a clockwise direction about the pivot 141 to the reset position (Fig. 1), wherein the extended projecting latch portion 145 (Fig. 3) of the second latch member 117 is again latched in the window opening 135 of the leg 133. When the handle 77 (Fig. 1) is moved to reset and relatch the breaker, the handle is moved close to the limit of movement in the opening 79. Upon release of the handle 77 following a resetting and relatching operation, the springs 73 return the handle 77 to the reset position and the magnetic trip actuator 147 automatically resets and the plunger 148 is maintained in the reset position by permanent magnetic means is disclosed in the specification of U.S. Patent No. 3,783,423.

The leg 137 (Fig. 3) of the leg 133 has an opening therein. A pin member 175 includes a lower portion that extends through the opening in the arm 137 and an upper portion that engages an adjustable screw 177 that is disposed in the lower end of a pushbutton 179 that is positioned in an opening 181 in the insulating cover 13.

The spring 160 biases the third latch member 131 in a clockwise direction to the latched position (Fig. 1) and biases the member 175 upward to thereby bias the push button 179 to the upper unactuated position (Fig. 1). When the circuit breaker is in the closed position and it is desired to manually trip the circuit breaker, the push button 179 is pressed downwardly against the bias of the spring 160 to move the third latch member 131 in a counterclockwise direction to the tripped position to release the latched structure 67 and the releasable member 61 to thereby trip the circuit breaker in the same manner as was hereinbefore described. During the manual push-to-trip operation, the armature plunger 148 remains in the initial unactuated position (Figs. 1, 3).Following a manual push-to-trip operation the circuit breaker is relatched in the same manner as was hereinbefore described by movement of the handle 77 to the resetting position.

A schematic diagram of solid-state circuitry (Fig. 7) is disclosed in the specification of U.S. Patent No. 3,818,275, in which reference numerals are primed to distinguish those reference numerals from similar reference characters hereinbefore used. The circuit breaker CB2, which represents the circuit breaker 5 herein disclosed, is a three-pole circuit breaker operated by means of a single trip coil TC2 which represents the trip coil used in the magnetic trip actuator 147 (Fig. 1). The three-pole circuit breaker simultaneously interrupts the three phases L1, L2 and L3. Separate current transformers CT1, CT2, CT3 are magnetically coupled to the separate conducting lines L1, L2, L3 respectively, and are connected at the output terminals thereof to the input terminals of separate full wave bridge rectifier circuits DB1, DB2, DB3 are connected in series or auctioneering electrical circuit relationships to produce a current which flows to a solid-state or static type control system indicated at 12'. The output of the single circuit 12' is connected to a single timing circuit 30' which provides energy for actuating the single static switch or control means Q3 to thereby energize the trip coil TC2 which, as was hereinbefore described, is the trip coil of the magnetic trip actuator 147 (Fig. 1). The single trip coil TC2 operates the circuit breaker to simultaneously open the three movable contact structure of the three-pole circuit breaker.

In accordance with this invention, an adjustable rating selector or switch 187 (Figs. 5, 6) is provided within the cover 13. The adjustable rating selector or switch 187 is an improvement over the plug-in rating adjustor of prior art construction, such as disclosed in the specification of U.S. Patent No. 3,826,951,- by which each adjustor was adapted for one current rating and was replaceable by a plug-in resistor of a different current rating when necessary.

The adjustable rating selector or switch 187 comprises a plurality of resistors 189, one for each current rating, connected in series and operable with a wiper 191. The adjustable rating selector or switch 187 is mounted on a circuit board 193 (Fig. 5). The switch 187 includes an indicator disk 195 on which the several current ratings are printed and the disk is mounted on a shaft 197 on which the wiper 191 is fixedly mounted. Suitable means for turning the shaft for adjusting the current rating is provided, such as a slot 199 for a screwdriver (Fig. 7).

The adjustable rating selector 187 and the disk 195 are located within the housing adjacent to the cover 13 (Fig. 5). Within the cover 13 the switch is inaccessible to unauthorized personnel for surreptitious manipulation that could result in improper settings of the switch in resolving damage to the cable system for which the circuit breaker is provided to protect. A window 201 (Figs. 5, 7) is provided in the cover to enable viewing of the current rating at which the switch 187 is set. In Fig. 7 the adjustable rating selector or switch 187 is shown in the circuitry which accompanies the circuit breaker 5.

The continuous current setting control of an adjustable circuit breaker is not adjustable to a value greater than the marked ampere rating of the circuit breaker. Adjustable circuit breakers can be repeatedly adjusted in the field as concerns all changeable characteristics. The adjustable circuit breaker is restricted so that the continuous current point, and other associated responses, once fixed at a particular value, cannot be changed to a higher value, except by removing the breaker cover which requires the use of a tool.

In conclusion, the primary advantage of the adjustable rating selector of this invention is that a single selector having several resistors that can be switched to desired rating plus means to prevent unauthorized changing without a required tool is provided.

Claims (3)

CLAIMS:

1. A circuit breaker having an adjustable rating selector, comprises a housing, a circuit breaker structure mounted within the housing and having a pair of separable contacts operable between open and closed positions to interrupt an electrical circuit, releasable means operable from a latched to a tripped position to automatically open the contacts, and an operating mechanism for moving the contacts between open and closed position, trip means responsive to current flow through the contacts for actuating the releasable means from the latched position to the tripped position to automatically open the contacts upon detection of overcurrent conditions, the trip means comprising a manual selector having a plurality of positions of incremental ratings for adjusting the level of overcurrent that will operate the trip means, the manual selector being located within the housing, the housing including a removable cover to enable access to the manual selector, the cover including a window and indicia for each rating position being alignable with the window, the manual selector including a rotary switch and an indicator disk, and the disk having the indicia for each rating position alignable with the window.

2. A circuit breaker as claimed in claim 1 in which the rotary switch is coupled with a printed circuit board.

3. A circuit breaker, constructed and adapted for use substantially as hereinbefore described and illustrated with reference to the accompanying drawings.