CA2105918C - Solid copper bus shunt through ground fault circuit breaker electronic - Google Patents
Solid copper bus shunt through ground fault circuit breaker electronic Download PDFInfo
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- CA2105918C CA2105918C CA 2105918 CA2105918A CA2105918C CA 2105918 C CA2105918 C CA 2105918C CA 2105918 CA2105918 CA 2105918 CA 2105918 A CA2105918 A CA 2105918A CA 2105918 C CA2105918 C CA 2105918C
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Abstract
A ground fault circuit breaker (1) has line and neutral bus bars (101, 103) extending through the center apertures (105, 107) of two laterally spaced toroidal coils (97, 99) to form the primaries of ground fault sensing transformers. The bus bars (101, 103) have flat center sections (101a, 103a) extending between the two coils (97, 99) parallel to the coil end faces and offset laterally by flat laterally extending legs (101b, 101c, 103b, 103c) at each end which are bent transverse to the end faces of the coils and extend through the coil apertures (105, 107) in flat confronting relation. The leg (103c) on one end of the neutral bus bar (103) has a terminal portion (103c') bent into a plane parallel to the center section with a crimp (103d) at the end for attachment to a neutral pigtail (11). Also provided are insulating barriers (235, 237) for flat, confronting C-shaped bus bars (101, 103) with facing, depending end portions (101b, 101c, 103b, 103c) are inte-grally formed with a pair of confronting C-shaped insulat-ing members (237, 239, 263, 265) conforming to the shape of the bus bars and joined by a pair of projections (253, 259, 261) extending between and electrically insulating the facing, depending end portions from each other. Both the fixed and movable contacts (135, 137) of the ground fault test switch (17) are directly secured to the printed circuit board (31) on which the ground fault detection circuit (119) is implemented, with the movable contact (137) also providing the spring bias for the test button (139).
Description
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to circuit breakers with ground fault protection, test circuits and insulating barriers, and more particularly, to small circuit breakers with toroidal sensing coils through which the power and neutral leads are passed to sense ground faults.
Background Information There is increasing demand today to provide ground fault protection in circuit breakers, including the small circuit breakers typically used in residential and light industrial and commercial applications. The physical dimensions of the molded casings for such circuit breakers are constrained by the standardized openings in the enclo sures and cabinets in which such circuit breakers are mounted. Thus, there is little room within the molded casing of such circuit breakers for adding the components necessary to provide the ground fault protection.
Common ground fault protection circuits include flat toroidal sensing coils through which the power and neutral leads pass to form transformers. Electronics connected to the sensing coils detect ground fault currents and energize a trip coil which trips the circuit breaker.
The limited space available within the circuit breaker molded case restricts the size of the sensing coils that can be used. This in turn limits the size of the power and _ ~~.Oa~lB
Field of the Invention This invention relates to circuit breakers with ground fault protection, test circuits and insulating barriers, and more particularly, to small circuit breakers with toroidal sensing coils through which the power and neutral leads are passed to sense ground faults.
Background Information There is increasing demand today to provide ground fault protection in circuit breakers, including the small circuit breakers typically used in residential and light industrial and commercial applications. The physical dimensions of the molded casings for such circuit breakers are constrained by the standardized openings in the enclo sures and cabinets in which such circuit breakers are mounted. Thus, there is little room within the molded casing of such circuit breakers for adding the components necessary to provide the ground fault protection.
Common ground fault protection circuits include flat toroidal sensing coils through which the power and neutral leads pass to form transformers. Electronics connected to the sensing coils detect ground fault currents and energize a trip coil which trips the circuit breaker.
The limited space available within the circuit breaker molded case restricts the size of the sensing coils that can be used. This in turn limits the size of the power and _ ~~.Oa~lB
neutral leads which must pass through the central aperture of the toroidal sensing coils, and therefore limits the current rating of the circuit breaker. The problem is compounded in circuit breakers which provide neutral to ground fault protection as well as power lead to ground fault protection. These latter circuit breakers require two sensing coils in a commonly used ground fault protec-tion circuit. Typically, these two flat toroidal coils have been mounted side by side within the circuit breaker molded housing which requires that the neutral and power leads bend 90° after passing through the coil in order to bridge the gap between the two sensing coils. This in-creases the overall thickness of the assembly, and hence the space required within the molded housing.
There is a known ground fault circuit breaker in which the two sensing coils are stacked in spaced relation with straight bus bars extending along the aligned axes through the coils. However, this makes the assembly wider.
There is a need therefore for a circuit breaker with ground fault protection having an increased current rating, yet of a physical size which can be contained within the standard size molded housing.
There is also a need to simplify the design of these mass-produced ground fault circuit breakers to reduce component and labor costs. This includes simplifying the ground fault test circuit.
SUMMARY OF THE INVENTION
This need and others are satisfied by the inven tion which is directed to a circuit breaker with ground fault protection in which the power and neutral leads which pass through the ground fault sensing coils are in the form of flat bus bars. These flat bus bars have an outer section extending parallel to the end face of the toroidal sensing coil and an end section extending laterally from the center section and bent transverse thereto to extend through the central aperture in the toroidal sensing coil.
The flat bus bars for the power lead and neutral lead have the end sections extending laterally from opposite sides of the conducting suctions and bent in flat confronting relation to pass through the central aperture in the toroidal coil. This laterally spaces the center sections of the bus b~~rs.
Pre.ferab7Ly, confronting additional end sections extend latez-ally from the opposite end of the center section of each bus bar and are bent into flat confronting relation to each other. These end sections can extend through a second toroidal sensing coil in circuit breakers which also provide neutral to ground fault protection.
One end section of the neutral bus bar has a terminal pori~ion with a crimp at the end for securing the bus bar to a neutral pigtail. Preferably, the terminal portion is bent transverse to the end section so that it is substantiall;~ parallel to the flat center section. Where the routing of the pigtail makes it desirable, the crimped end can be angled in the plane of the flat terminal portion of the end section of the neutral bus bar. In circuit breakers whi~~h have line to ground fault protection, but not neutral t:o ground fault protection, and therefore only one toroidal coil, the crimp for connection to the neutral pigtail can :be provided on either end of the neutral bus bar, but is preferably provided on the end which is not passed through the single toroidal coil.
It is an object of the present invention to provide improved residential light industrial and commer cial circuit breakers with ground fault protection having improved means for insulating the bus bars in the ground fault detector.
It is alsso an object of the invention to provide such improved insulating means which can be easily and economically installed and retained in place.
These objects and others are realized by an invention wh~_ch is directed to an insulating barrier for a pair of confronting flat C-shaped circuit breaker bus bars with facing depending end portions wherein the barrier comprises a pair of confronting C-shaped insulating members conforming to the shape of the flat C-shaped bus bars and joined by a pair of projections which extend between and electrically insulate the facing depending end portions of the bus bars from each other. Preferably, the insulating barrier is formed with flat linear sections joining the confronting C-shaped members which are then folded to form the projections. The C-shaped insulating members have edge extensions covering the edges of the bus bars. Grippers formed integrally with the edge extensions snap under the bus bars to secure the insulating member in place.
These and other needs are also satisfied by an invention which is directed to a ground fault circuit breaker in which the ground fault detection circuit is implemented on a printed circuit board, and wherein a fixed contact member and a resiliently deformable movable contact member, which also serves as a spring mount for the test button, are both directly mounted on the printed circuit board. More particularly, the resiliently deformable movable contact member comprises an electrically conductive metallic strip secured along a side edge at a first end to the printed circuit board. Preferably, this electrically conductive metallic strip has a base section extending from the first end secured to the printed circuit board, and a terminal section bent at an angle, preferably about 90°, to the base section and terminating in a free end which contacts the fixed contact member when the test button is depressed. Also preferably, the fixed contact member is an electrically conductive strip secured along a side edge at a first end to the printed circuit board with a base section spaced from the base portion of the movable elec trical contact, and a terminal portion generally parallel to or angled slightly toward, but spaced from the terminal portion of the electrically conductive metallic strip of the movable contact.
~. ~~o~~ls BRIEF DESCRIPTION OF THE DRAWINGS
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying 5 drawings in which:
Figure 1 is an isometric view of a ground fault circuit breaker to which the invention has been applied.
Figure 2 is a vertical section taken along the line 2-2 through the circuit breaker of Figure 1.
Figure 3 is another vertical section through the circuit breaker of Figure 1 taken along line 3-3.
Figure 4 is an exploded isometric view of the insulating barrier in accordance with the invention and showing the relationship of the barrier to other components of the circuit breaker.
Figure 5 is a cross section taken along the line 5-5 in Figure 3.
Figure 6 is an isometric view of another embodi ment of an insulating barrier in accordance with the invention.
Figure 7 is a schematic circuit diagram of the ground fault detector which forms part of the circuit breaker of Figures 1-3.
Figure 8 shows a portion of the region of the circuit breaker of Figure 3 in the region of the test switch.
Figure 9 is a fragment of Figure 3 showing the test switch of the invention in the actuated position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be shown as applied to a single pole residential or light commercial or industrial ground fault circuit breaker; however, it will be evident to those skilled in the art that the invention is also applicable to multi-pole circuit breakers as well.
Referring to Figure 1, the ground fault circuit breaker 1 comprises a housing 3 which is composed of electrically insulating material such a thermo-setting resin. A load tez-minal 5 and load neutral terminal 7 are provided for connecting the circuit breaker to a load. A
line terminal 9 (see Figure 2) is provided. at the opposite end of the housing 3 for connection to a commercial power system. ThE: line side of the neutral is connected to a pigtail 11. The ground fault circuit breaker 1 includes an operating member :13 having an integral molded handle 15 extending through the housing 3. A ground fault test switch 17 is also accessible through the housing.
The: housing 3 defines a compartment 19 (see Figure 2) in which a circuit breaker mechanism 21 is housed, and a second compartment 23, separated from the compartment 19 by a center panel 25, which houses a ground fault circuit interrupter :~7 (see Figure 3).
The. circuit breaker mechanism 21 is of the type disclosed in U.S. Patent No. 3,566,318 which includes a complete description of its structure and operation.
Briefly, the circuit breaker mechanism 21 includes a pair of separable contacts 29, including a fixed contact 31 and a movable contact: 33, a supporting metal frame 35, an operating mechan.i~>m 37, and a trip device 39. The fixed contact 31 is connected by a conductor 41 to the line terminal- 9.
The operating mechanism 33 includes a flat elec trically conductive generally C-shaped contact arm 43 to which the moldable contact 33 is secured at the lower end.
The upper end of t:he contact arm has a notch 45 which is biased again:~t a projection 47 on the operating member 13 in a manner to be discussed. The operating member is mounted in the hou:~ing 3 for rotation about an axis perpen dicular to the plane of Figure 2. Motion is transmitted from the operating member 13 to the contact arm 43 when the circuit breaker 1. is manually operated, and from the contact arm X63 to the operating member 13 when the breaker is automatically gripped.
The operating mechanism 37 further includes a latchable cradle 49 which is pivotally supported at one end _r ~~o~o~s by a pivot 51 molded into the center panel 25. The other end 53 of the cradle 49 is latched by the trip device 39 in a manner to be discussed.
As more specifically described in U.S. Patent No.
3,254,176, the ends of the latchable cradle 49 are offset and disposed along a plane which is parallel to a plane in which the main body portion of the latchable cradle 49 is disposed. This places the ends of the cradle 49 in the same plane as the C-shaped contact arm 43. A spring 55 is connected, under tension, at one end in a slot 57 near the lower end of the C-shaped contact arm 43, and at the other end to a bent over tab 59 projecting outward from the main body of the latchable cradle 49.
The trip device 39 includes a bimetal 61 secured at an upper end to a bent over tab 63 on the frame 35. The contact arm 43 of the operating mechanism 37 is connected to the lower end of the bimetal 61 by a flexible conductor 65. The upper end of the bimetal 61 is connected by another flexible conductor 67 to the ground fault detector discussed below which in turn is connected to a tang 69 extending through an opening in the end wall of the housing 3. The load terminal 5 is connected to the external end of the tang 69 for connection of the circuit breaker to a load. The closed circuit through the circuit breaker 1 extends from the line terminal 9, conductor 41, fixed contact 31, movable contact 33, contact arm 43, flexible conductor 65, bimetal 61, flexible conductor 67, the ground fault detector, tang 69, and load terminal 5.
The trip device 39 further includes an elongated, rigid magnetic armature or latch member 71 mounted on a spring 73 which is welded to the free lower end of the bimetal 61. The magnetic armature 71 extends generally upward along side the bimetal 61, and has an opening 75 forming a latch surface 77 at the base of the opening. The latch end 53 of the cradle 49 is formed with a latch surface 79 and a stop surface or fulcrum part 81. The armature 71 serves as a stop to engage the fulcrum part 81 ~~.0~~18 of the latchable cradle 49 in the latched position of the cradle. A U-shaped magnetic member 83 is secured to the bimetal 61 adj acent the magnetic armature 71 to concentrate the flux created by current flowing through the bimetal.
The circuit breaker is shown in Figure 2 in the tripped position. The cradle 49 is latched for resetting the circuit breaker by rotating the handle 15 clockwise, as shown in Figure 2. This causes a projection 85 on the operating member 13 to engage the tab 59 and rotate the latchable cradle 49 in the counterclockwise direction until the latch end 53 is latched in the opening 75 in the magnetic armature 71. This operation is shown in detail in U.S. Patent No. 3,566,318.
The separable contacts 29 are closed by moving the handle 15, with the cradle 49 latched, in the counter clockwise direction as viewed in Figure 2 to the on posi tion. This causes the projection 47 on the operating member 13 which engages the notch 45 in the contact arm 43 to move the upper end of the contact arm to the right of the line of action of the spring 55 resulting in closure of the contacts 29. The contacts 29 could be manually opened from this closed position by rotating the handle 15 clock-wise, as viewed in Figure 2, to the off position.
The trip device 39 provides over-current protec tion through the bimetal 61. Prolonged current above the rated current of the circuit breaker heats the bimetal 61 causing the lower end to deflect to the right, as shown in Figure 2 , thereby unlatching the cradle 49 , as the armature 71 pivots about the fulcrum 81 until the latch surface 79 on the latch end 53 of the cradle slides off of the latch surface 77. When unlatched, the cradle 49 is rotated clockwise by the spring 55 until it engages a stop pin 87 molded in the center panel 25 of the circuit breaker housing. During this movement, the line of action of the spring 55 moves to the right of the pivot formed by the notch 45 in the contact arm and the projection 47 on the operating member 13, whereupon the spring 55 biases the contact arm 43 in the opening direction to open the con-tacts 29 and move;~ the contact arm 43 so that the line of action of th.e force exerted by the spring on the operating member 13 shifts across the rotational axis of the operat-ing member 13 and actuates the operating member to the tripped position :shown in Figure 2. The tripped position of the oper~~ting member 13 is intermediate the "on" and "off" positions. The operating member 13 is stopped in the intermediate or tripped position seen in Figure 2 when the projection ~;5 eng,ages the tab 59 on the cradle 49. The contact arm 43 i:~ stopped in the open position seen in Figure 2 whE~n it engages the stop pin 87. The circuit breaker is r<~set following the trip in the manner discussed above.
ThE: trip device 39 also provides short circuit protection. The very high current through the bimetal 61 produced by a short circuit induces a magnetic flux which is concentrated by the magnetic member 83 and of sufficient magnitude to attract the armature 71 to the magnetic member, thereby unlatching the cradle 49 to trip the circuit breaker.
As discu:~sed, the circuit breaker 1 also provides ground fault protection, both for line to ground faults and neutral to ground faults. All the components for ground fault protection are mounted on a printed circuit board 91 in the compa.rtmeni: 23 formed in the molded housing 3 as shown in Figure 3. The printed circuit board 91 is posi-tioned within the compartment 23 by a pin 95 molded into the center panel 25. A suitable ground fault protection circuit 119 is of the well-known dormant oscillator type.
This circuit includes two transformers formed by toroidal sensing coil; 97 and 99. The primaries of the transformers are formed ~>y passing a neutral conductor 101 and a line conductor 103 through the central openings 105 and 107 in the sensing coils 97 and 99, respectively.
_ 21.05018 These conductors 101 and 103 are flat bus bars formed from sheet material. As best seen in Figure 4, the neutral bus bar 101 has a flat center section 101a extend-ing parallel to a common plane P containing the end faces 5 of the toroidal coils 97 and 99. A flat leg section 101b extends generally laterally from the upper end of the center section of 101a and is bent substantially at a right angle to the flat center section. A second leg section 101c extends generally laterally from the lower end of the 10 center section 101a and is bent transversely to the flat center section. A terminal portion lOlc' of the leg lOlc is bent generally perpendicular to the leg 101c to extend in a plane generally parallel to the plane of the flat center section 101a. A crimp 101d is formed in the end of the terminal portion 101c'. Preferably, this crimp 101d is bent at an angle in the plane of the terminal portion 101c' for a purpose to be discussed.
The line bus bar 103 also has a flat center section 103a and a first leg section 103b extending gener ally laterally from the upper end center section and bent generally perpendicular to the plane of the center section 103a. A second leg section 103c extends laterally from and is bent generally perpendicular to the lower end of the flat center section 103a.
The upper legs 101b and 103b and the lower legs 101c and 103c extend from opposite sides of the respective center sections 101a and 103a of the neutral bus bar 101 and the line bus bar 103 so that when the two bus bars are placed side by side the flat upper leg sections 101b and 103b, and the flat lower leg sections 101c and 103c, are in spaced, flat confronting relation. The upper leg sections 101b and 103b extend through the central aperture 105 of the toroidal coil 97 while the leg sections 101c and 103c extend through the central aperture 107 in the toroidal coil 99.
__ 210~~18 The crimp 101d on the terminal portion 101c' of the lower leg 101c on the neutral bus bar 101 secures this bus bar to the neutral pigtail 11. The crimp 101d is bent at an angle to the terminal portion 101c' of the lower leg 101c so that the pigtail is lead directly from the crimp to the opening 111 in the housing 3. The upper leg 101b of the neutral conductor 101 is connected by an insulated lead 110 to a tang 113 which is secured to the load neutral terminal 7. This upper end of the neutral bus bar 101 is also connected by the lead 112 to the printed circuit board 91.
The lower end of the line bus bar 103 is connected by the flexible conductor 67 to the bimetal 61 and is also connected by a lead 114 to the printed circuit board 91.
The upper end of the line bus bar 103 is connected through an opening in the central panel 23 to the tang 69 leading to the load terminal 5. The windings on the toroidal sensing coils 97 and 99 form the secondaries of the sensing transformers.
In an exemplary embodiment of the invention, the neutral bus bar 101 and line bus bar 103 are formed from copper sheet material having a thickness of 0.047 inches (1.2 mm). The center sections are .135 inches (3.4 mm) wide and the legs are .125 inches (3.175 mm) wide. With these bus bars, the circuit breaker 1 has a rated current of 50 amperes. With the prior art insulated wire used as the neutral and line conductors for the sensing transform-ers, the 0.220 inch (5.59 mm) diameter of the central apertures 105 and 107 of the sensing coils limit the rated current of the circuit breaker 1 to 30 amps using 10 gauge twisted wire. Thus, the bus bars 101 and 103 allow the rating of the ground fault circuit breaker to be increased without major modification to the circuit breaker struc-ture.
The neutral and line bus bars 101 and 103 are electrically insulated from each other, and from surround-ing components by a one piece insulating barrier 235. The mo5~ts insulating barrier 235 comprises a pair of confronting C-shaped insulating members 237 and 239 in a common plane R
joined by linear sections 241 and 243. The C-shaped members 237 and 239 conform to the shape of the center portions 101a and 103a and the portions of the bent legs B
and C which are in the same plane as the center sections.
These C-shaped members 237 and 239 have edge extensions 245 and 247, respectively, which extend over the side edges of the conductors 101 and 103. The linear sections 241 and 243 join the C-shaped members 237 and 239 in the plane of the bottom edge extensions 245 and 247. These linear sections 241 and 243 are hinged at their connections 241A
and 243A with the C-shaped member 237 and at hinge connec-tions 241B and 243B at the connection with the C-shaped member 239. The linear sections 241 and 243 are also formed with score line 241C and 243C at their mid-points.
trippers 249 and 251 are molded into the edge extensions 245 and 247, respectively.
The insulating barrier 235 can be formed flat in a vacuum forming process. The linear sections 241 and 243 are then folded at the hinge lines 241a-b, 243a-b and score lines 241c and 243c to form projections 253 which extend transverse to the common plane of the C-shaped members 237 and 239 as shown in Figure 5. This also brings the C
shaped members 237 and 239 close together to the same spacing as the conductors 101 and 103. The projections 253 are then pressed between the facing depending legs 101B, 103B and 101C, 103C, respectively, with the C-shaped members 237 and 239 fitting down over the center sections 101A and 103A. The grippers 249 and 251 snap under the bottom surfaces of the conductors 101 and 103 to secure the insulating barrier 235 in place. A suitable material for the insulating barrier 235 is 0.010 inches or .25 thick polycarbonate.
An alternate form of the insulating barrier 257 is illustrated in Figure 6. In this embodiment, the insulat-ing barrier 257 is formed with the projections 259 and 261.
._ 210~~18 These projections 259 and 261 space the confronting C-shaped members 263 and 265 properly to snap over the conductors 101 and 103, without folding, as in the previ-ously described embodiment.
In operation, upon detection of a grounded load conductor or a grounded load neutral conductor through the toroids 97 or 99, the ground fault circuit 119 energizes a trip solenoid 123. Energization of the trip solenoid 123 results in extension of the solenoid plunger 127. A flag 129 secured to the plunger extends through a slot 131 in the center panel 25 and pushes the armature 71 to the right as viewed in Figure 2 to trip the circuit breaker thereby opening the separable contacts 29.
In order to allow for periodic verification of the operation of the circuitry, a test circuit is provided which includes the test switch 17, accessible from the outside of the housing 3 as seen in Figure 1. More specif ically, a test wire 121 is connected between the neutral conductor 101 and the load conductor 103 by way of the test switch 139 of the test switch 17, which closes contacts 135 and 137, and is routed through the toroid 97 (Fig. 3) to induce a signal in the secondary winding T1 to simulate a ground fault condition. Upon actuation of the test button 139, a ground condition is simulated, resulting in a trip of the circuit breaker through energization of the trip solenoid 123.
The lower end of the neutral 101 is welded to the end of the pigtail 11 extending through an opening 111 in the housing 3 for connection to a panel neutral. The upper end of the neutral lead 1a1 is connected to the printed circuit board by a lead 112 and to a tang 113 leading to the load neutral terminal 7. The lower end of the line lead 103 is connected to the flexible conductor 67 leading from the bimetal 61 and by lead 114 to the printed circuit board, while the upper end is connected through an opening in the central panel 23 to the tang 69 leading to the load terminal 5. The windings T1 and T2 on the toroidal sensing coils 97 and 99 form the secondaries of the transformers.
The schematic diagram of the circuit 119 of the ground fault detector which is mounted on the printed circuit board.91 is. illustrated in Figure 7. The circuitry 119 includes the sensing toroids 97 and 99 with secondary windings T1 and T2, respectively. As previously discussed, the line conductors 103 as well as the neutral conductor 101, are routed through the toroids 97 and 99. Additional-1y, a test conductor 121 is routed through the upper toroid 97.
The toroid 97 is used for sensing ground faults.
During normal conditions, the magnetic fields generated by the conductor 103 amd the neutral conductor 101 cancel and therefore do not induce a voltage on the secondary winding T1 of the thyroid 97. However, during a ground fault condition, there will be a resultant magnetic field which will induce a voltage in the secondary winding T1 which, in turn, will energizE: a trip solenoid 123 by way of a ground fault interrupter integrated circuit IC1, as discussed below.
The toroi.d 99 is used in conjunction with the toroid 97 fo:r sensing a grounded neutral condition. As discussed in Linear Integrated Circuits 1989 by Raytheon Corporation, Section 10 on pages 10-16 through 10-21, a grounded nE~utral will close a magnetic path between the toroids 97 and 99. The resultatant AC coupling closes a feedback path around an operational amplifier in the IC1 causing the operational amplifier to oscillate. When the peaks of the oscillation voltage exceed an CR trigger comparator threshold within the IC1, the IC1 output will go high. Circuitry for detecting a grounded neutral condition is also disclosed in United States Reissue Patent No.
30,678.
'1'L1C secondary windings T1 and T2 of the toroids 97 and 99, respectively, are applied to a low power ground fault interrupter integrated circuit IC1, such as a Raytheon RV4:145 or a TRC-10020 by Technology Research Corporation of Clearwater, Florida. More specifically, one side of the secondary winding T1 is applied to pin 3 of the integrated circuit IC1. The other side of the secondary winding T1 is applied to pin 1 of the IC1 by way of the resistor R1 and serially coupled capacitor C1. A resistor R2 is connected between pins 1 and 8 of the integrated circuit IC1. The resistors R1 and R2 determine an amplifi-cation factor for an operational amplifier within the integrated circuit IC1. Exemplary values for the resistors R1 and R2 are 150 ohms and 1 megohm, respectively. The capacitor C1 which may be, for example, 15 microfarads acts as a coupling capacitor. A noise capacitor C2, for exam-ple, 0.01 microfarads is connected between pins 1 and 2 of the integrated circuit IC1.
One side of the secondary winding T2 is connected to the secondary winding T1 that is connected to pin 3 of the integrated circuit IC1. The other side of the second-ary winding T2 is connected to a tuning capacitor C3, for example, 1 microfarad. The other side of the tuning capacitor C3 is connected to the resistor R2, pins 7 and 8 of the integrated circuit IC1 as well as to a noise capaci-tor C4, for example, 0.01 microfarads. The other side of the noise capacitor C4 is connected to pin 4 of the inte-grated circuit IC1.
The winding of the trip solenoid 123 is connected on one end to the line conductor 103 with the other end connected to a full wave rectifier, generally indicated by the reference numeral 125, and including the diodes D1, D2, D3 and D4. The do output of the full wave rectifier 125 is connected across a silicon controlled rectifier SCR 1.
The gate terminal of the silicon controlled rectifier SCR
1 is connected to pin 5 of the integrated circuit IC1. A
noise capacitor C5, for example 6.8 microfarads is connect-ed between the gate terminal of the silicon controlled rectifier SCR 1 an pin 4 of the integrated circuit IC1 to prevent spurious triggering of the silicon controlled rectifier SCR 1.
A resistor R4, for example 30 kilohms, is con-nected between full wave rectifier 132 and pin 6 of the integrated c:ircuiit IC1. This resistor limits the current to the :shunt regulator within the integrated circuit IC1. Surge protective devices, such as the varistors RV:L and :RV2 are used to protect the circuit from overvoltage.
In operai:ion, upon detection of a grounded load conductor or a grounded load neutral conductor by the toroids 97 or 99, a voltage is induced in the secondary windings T1 <~nd T2. This voltage, in turn, is applied to the integrated circuit IC1. During such conditions, pin 5 of the integrated circuit IC1 enables the gate terminal to fire the silicon controlled rectifier SCR 1, which, in turn, energi2;es thE; trip solenoid 123. Energization of the trip solenoid 123 results in extension of the solenoid plunger 127. A flag 129 secured to the plunger extends through a slot 131. in the center panel 25 and pushes the armature 71 t:o the right as viewed in Figure 2 to trip the circuit breal~:er thereby opening the separable contacts 29.
In order to allow for periodic verification of the operation of the circuitry, a test circuit 132 is provided which includes thc~ test switch 17, accessible from the outside of the hour>ing 3 as seen in Figure 1. More specif ically, the test wire 121 is connected between the load neutral conductor 101 and the load conductor 103 by way of the test switch 17, and a resistor R3, for example 15 kilohms, and is routed through the toroid 97 (Fig. 3) to induce a signal in the secondary winding T1 to simulate a ground fault condii~ion. Upon actuation of the test button 17, a ground condition is simulated, resulting in a trip of the circuit breaker through energization of the trip solenoid 123.
Referring to Figures 3, 8 and 9, the test switch 17 includes a. fixed contact 135, a movable contact 137 and a test button 139. The fixed contact 135 and the movable contact 137 each comprise an electrically conductive metallic strip, suc:h as a copper strip. The metallic strip of the fixed contact 135 has a base section 141 which is secured alone a side edge 143 to the printed circuit board by a latera:Lly e:~tending projection 145 which extends ._ through the printed circuit board and is soldered in place on the back of the printed circuit board. The solder joint 146 also electrically connects the fixed contact 135 to a lead trace 147 in the test circuit of the printed circuit board. The fixed contact has a terminal section 148 cantilevered laterally from the end of the base section 141. The movable contact 137 similarly has a base section 149 and a terminal section 151 and is similarly secured along the side edge of the base section 149 to the printed circuit board. The fixed and movable contacts 135 and 137 are nested in spaced relation with the base portions substantially parallel. The terminal section 151 of the movable contact 137 extends at substantially a right angle to the base section 149, while the angle between the base section and terminal section of the fixed contact is slightly greater than a right angles so that the terminal section 148 angles slightly toward the terminal section 151 of the movable contact 137.
The test button 139 includes an enlarged head portion 153 which is received in a recess 155 in an upward ly extending bass 157 molded into the housing 3. A stem 159 on the underside of the head 153 extends through a guide opening 161 in the housing 3 and terminates and an enlarged terminal portion 163. The terminal section 151 of the movable contact 137, which is resiliently deformable, being made of copper, bears against the terminal portion 163 and biases the button to the full upward or unactuated position shown in Figure 3. The button 139 is retained by the terminal portion 163 which bears against the portion of the housing 3 forming the guide opening 161. With the test switch 17 in its unactuated position, the test circuit 119 is open circuited. When the ground fault detector is to be tested, the test button 139 is depressed thereby resilient-ly deforming the movable contact 137 to bring it into electrical contact with the fixed contact 135 to complete the test circuit as shown in Figure 6.
._ ~10~~18 While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alterna-tives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustra-tive only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.
There is a known ground fault circuit breaker in which the two sensing coils are stacked in spaced relation with straight bus bars extending along the aligned axes through the coils. However, this makes the assembly wider.
There is a need therefore for a circuit breaker with ground fault protection having an increased current rating, yet of a physical size which can be contained within the standard size molded housing.
There is also a need to simplify the design of these mass-produced ground fault circuit breakers to reduce component and labor costs. This includes simplifying the ground fault test circuit.
SUMMARY OF THE INVENTION
This need and others are satisfied by the inven tion which is directed to a circuit breaker with ground fault protection in which the power and neutral leads which pass through the ground fault sensing coils are in the form of flat bus bars. These flat bus bars have an outer section extending parallel to the end face of the toroidal sensing coil and an end section extending laterally from the center section and bent transverse thereto to extend through the central aperture in the toroidal sensing coil.
The flat bus bars for the power lead and neutral lead have the end sections extending laterally from opposite sides of the conducting suctions and bent in flat confronting relation to pass through the central aperture in the toroidal coil. This laterally spaces the center sections of the bus b~~rs.
Pre.ferab7Ly, confronting additional end sections extend latez-ally from the opposite end of the center section of each bus bar and are bent into flat confronting relation to each other. These end sections can extend through a second toroidal sensing coil in circuit breakers which also provide neutral to ground fault protection.
One end section of the neutral bus bar has a terminal pori~ion with a crimp at the end for securing the bus bar to a neutral pigtail. Preferably, the terminal portion is bent transverse to the end section so that it is substantiall;~ parallel to the flat center section. Where the routing of the pigtail makes it desirable, the crimped end can be angled in the plane of the flat terminal portion of the end section of the neutral bus bar. In circuit breakers whi~~h have line to ground fault protection, but not neutral t:o ground fault protection, and therefore only one toroidal coil, the crimp for connection to the neutral pigtail can :be provided on either end of the neutral bus bar, but is preferably provided on the end which is not passed through the single toroidal coil.
It is an object of the present invention to provide improved residential light industrial and commer cial circuit breakers with ground fault protection having improved means for insulating the bus bars in the ground fault detector.
It is alsso an object of the invention to provide such improved insulating means which can be easily and economically installed and retained in place.
These objects and others are realized by an invention wh~_ch is directed to an insulating barrier for a pair of confronting flat C-shaped circuit breaker bus bars with facing depending end portions wherein the barrier comprises a pair of confronting C-shaped insulating members conforming to the shape of the flat C-shaped bus bars and joined by a pair of projections which extend between and electrically insulate the facing depending end portions of the bus bars from each other. Preferably, the insulating barrier is formed with flat linear sections joining the confronting C-shaped members which are then folded to form the projections. The C-shaped insulating members have edge extensions covering the edges of the bus bars. Grippers formed integrally with the edge extensions snap under the bus bars to secure the insulating member in place.
These and other needs are also satisfied by an invention which is directed to a ground fault circuit breaker in which the ground fault detection circuit is implemented on a printed circuit board, and wherein a fixed contact member and a resiliently deformable movable contact member, which also serves as a spring mount for the test button, are both directly mounted on the printed circuit board. More particularly, the resiliently deformable movable contact member comprises an electrically conductive metallic strip secured along a side edge at a first end to the printed circuit board. Preferably, this electrically conductive metallic strip has a base section extending from the first end secured to the printed circuit board, and a terminal section bent at an angle, preferably about 90°, to the base section and terminating in a free end which contacts the fixed contact member when the test button is depressed. Also preferably, the fixed contact member is an electrically conductive strip secured along a side edge at a first end to the printed circuit board with a base section spaced from the base portion of the movable elec trical contact, and a terminal portion generally parallel to or angled slightly toward, but spaced from the terminal portion of the electrically conductive metallic strip of the movable contact.
~. ~~o~~ls BRIEF DESCRIPTION OF THE DRAWINGS
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying 5 drawings in which:
Figure 1 is an isometric view of a ground fault circuit breaker to which the invention has been applied.
Figure 2 is a vertical section taken along the line 2-2 through the circuit breaker of Figure 1.
Figure 3 is another vertical section through the circuit breaker of Figure 1 taken along line 3-3.
Figure 4 is an exploded isometric view of the insulating barrier in accordance with the invention and showing the relationship of the barrier to other components of the circuit breaker.
Figure 5 is a cross section taken along the line 5-5 in Figure 3.
Figure 6 is an isometric view of another embodi ment of an insulating barrier in accordance with the invention.
Figure 7 is a schematic circuit diagram of the ground fault detector which forms part of the circuit breaker of Figures 1-3.
Figure 8 shows a portion of the region of the circuit breaker of Figure 3 in the region of the test switch.
Figure 9 is a fragment of Figure 3 showing the test switch of the invention in the actuated position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be shown as applied to a single pole residential or light commercial or industrial ground fault circuit breaker; however, it will be evident to those skilled in the art that the invention is also applicable to multi-pole circuit breakers as well.
Referring to Figure 1, the ground fault circuit breaker 1 comprises a housing 3 which is composed of electrically insulating material such a thermo-setting resin. A load tez-minal 5 and load neutral terminal 7 are provided for connecting the circuit breaker to a load. A
line terminal 9 (see Figure 2) is provided. at the opposite end of the housing 3 for connection to a commercial power system. ThE: line side of the neutral is connected to a pigtail 11. The ground fault circuit breaker 1 includes an operating member :13 having an integral molded handle 15 extending through the housing 3. A ground fault test switch 17 is also accessible through the housing.
The: housing 3 defines a compartment 19 (see Figure 2) in which a circuit breaker mechanism 21 is housed, and a second compartment 23, separated from the compartment 19 by a center panel 25, which houses a ground fault circuit interrupter :~7 (see Figure 3).
The. circuit breaker mechanism 21 is of the type disclosed in U.S. Patent No. 3,566,318 which includes a complete description of its structure and operation.
Briefly, the circuit breaker mechanism 21 includes a pair of separable contacts 29, including a fixed contact 31 and a movable contact: 33, a supporting metal frame 35, an operating mechan.i~>m 37, and a trip device 39. The fixed contact 31 is connected by a conductor 41 to the line terminal- 9.
The operating mechanism 33 includes a flat elec trically conductive generally C-shaped contact arm 43 to which the moldable contact 33 is secured at the lower end.
The upper end of t:he contact arm has a notch 45 which is biased again:~t a projection 47 on the operating member 13 in a manner to be discussed. The operating member is mounted in the hou:~ing 3 for rotation about an axis perpen dicular to the plane of Figure 2. Motion is transmitted from the operating member 13 to the contact arm 43 when the circuit breaker 1. is manually operated, and from the contact arm X63 to the operating member 13 when the breaker is automatically gripped.
The operating mechanism 37 further includes a latchable cradle 49 which is pivotally supported at one end _r ~~o~o~s by a pivot 51 molded into the center panel 25. The other end 53 of the cradle 49 is latched by the trip device 39 in a manner to be discussed.
As more specifically described in U.S. Patent No.
3,254,176, the ends of the latchable cradle 49 are offset and disposed along a plane which is parallel to a plane in which the main body portion of the latchable cradle 49 is disposed. This places the ends of the cradle 49 in the same plane as the C-shaped contact arm 43. A spring 55 is connected, under tension, at one end in a slot 57 near the lower end of the C-shaped contact arm 43, and at the other end to a bent over tab 59 projecting outward from the main body of the latchable cradle 49.
The trip device 39 includes a bimetal 61 secured at an upper end to a bent over tab 63 on the frame 35. The contact arm 43 of the operating mechanism 37 is connected to the lower end of the bimetal 61 by a flexible conductor 65. The upper end of the bimetal 61 is connected by another flexible conductor 67 to the ground fault detector discussed below which in turn is connected to a tang 69 extending through an opening in the end wall of the housing 3. The load terminal 5 is connected to the external end of the tang 69 for connection of the circuit breaker to a load. The closed circuit through the circuit breaker 1 extends from the line terminal 9, conductor 41, fixed contact 31, movable contact 33, contact arm 43, flexible conductor 65, bimetal 61, flexible conductor 67, the ground fault detector, tang 69, and load terminal 5.
The trip device 39 further includes an elongated, rigid magnetic armature or latch member 71 mounted on a spring 73 which is welded to the free lower end of the bimetal 61. The magnetic armature 71 extends generally upward along side the bimetal 61, and has an opening 75 forming a latch surface 77 at the base of the opening. The latch end 53 of the cradle 49 is formed with a latch surface 79 and a stop surface or fulcrum part 81. The armature 71 serves as a stop to engage the fulcrum part 81 ~~.0~~18 of the latchable cradle 49 in the latched position of the cradle. A U-shaped magnetic member 83 is secured to the bimetal 61 adj acent the magnetic armature 71 to concentrate the flux created by current flowing through the bimetal.
The circuit breaker is shown in Figure 2 in the tripped position. The cradle 49 is latched for resetting the circuit breaker by rotating the handle 15 clockwise, as shown in Figure 2. This causes a projection 85 on the operating member 13 to engage the tab 59 and rotate the latchable cradle 49 in the counterclockwise direction until the latch end 53 is latched in the opening 75 in the magnetic armature 71. This operation is shown in detail in U.S. Patent No. 3,566,318.
The separable contacts 29 are closed by moving the handle 15, with the cradle 49 latched, in the counter clockwise direction as viewed in Figure 2 to the on posi tion. This causes the projection 47 on the operating member 13 which engages the notch 45 in the contact arm 43 to move the upper end of the contact arm to the right of the line of action of the spring 55 resulting in closure of the contacts 29. The contacts 29 could be manually opened from this closed position by rotating the handle 15 clock-wise, as viewed in Figure 2, to the off position.
The trip device 39 provides over-current protec tion through the bimetal 61. Prolonged current above the rated current of the circuit breaker heats the bimetal 61 causing the lower end to deflect to the right, as shown in Figure 2 , thereby unlatching the cradle 49 , as the armature 71 pivots about the fulcrum 81 until the latch surface 79 on the latch end 53 of the cradle slides off of the latch surface 77. When unlatched, the cradle 49 is rotated clockwise by the spring 55 until it engages a stop pin 87 molded in the center panel 25 of the circuit breaker housing. During this movement, the line of action of the spring 55 moves to the right of the pivot formed by the notch 45 in the contact arm and the projection 47 on the operating member 13, whereupon the spring 55 biases the contact arm 43 in the opening direction to open the con-tacts 29 and move;~ the contact arm 43 so that the line of action of th.e force exerted by the spring on the operating member 13 shifts across the rotational axis of the operat-ing member 13 and actuates the operating member to the tripped position :shown in Figure 2. The tripped position of the oper~~ting member 13 is intermediate the "on" and "off" positions. The operating member 13 is stopped in the intermediate or tripped position seen in Figure 2 when the projection ~;5 eng,ages the tab 59 on the cradle 49. The contact arm 43 i:~ stopped in the open position seen in Figure 2 whE~n it engages the stop pin 87. The circuit breaker is r<~set following the trip in the manner discussed above.
ThE: trip device 39 also provides short circuit protection. The very high current through the bimetal 61 produced by a short circuit induces a magnetic flux which is concentrated by the magnetic member 83 and of sufficient magnitude to attract the armature 71 to the magnetic member, thereby unlatching the cradle 49 to trip the circuit breaker.
As discu:~sed, the circuit breaker 1 also provides ground fault protection, both for line to ground faults and neutral to ground faults. All the components for ground fault protection are mounted on a printed circuit board 91 in the compa.rtmeni: 23 formed in the molded housing 3 as shown in Figure 3. The printed circuit board 91 is posi-tioned within the compartment 23 by a pin 95 molded into the center panel 25. A suitable ground fault protection circuit 119 is of the well-known dormant oscillator type.
This circuit includes two transformers formed by toroidal sensing coil; 97 and 99. The primaries of the transformers are formed ~>y passing a neutral conductor 101 and a line conductor 103 through the central openings 105 and 107 in the sensing coils 97 and 99, respectively.
_ 21.05018 These conductors 101 and 103 are flat bus bars formed from sheet material. As best seen in Figure 4, the neutral bus bar 101 has a flat center section 101a extend-ing parallel to a common plane P containing the end faces 5 of the toroidal coils 97 and 99. A flat leg section 101b extends generally laterally from the upper end of the center section of 101a and is bent substantially at a right angle to the flat center section. A second leg section 101c extends generally laterally from the lower end of the 10 center section 101a and is bent transversely to the flat center section. A terminal portion lOlc' of the leg lOlc is bent generally perpendicular to the leg 101c to extend in a plane generally parallel to the plane of the flat center section 101a. A crimp 101d is formed in the end of the terminal portion 101c'. Preferably, this crimp 101d is bent at an angle in the plane of the terminal portion 101c' for a purpose to be discussed.
The line bus bar 103 also has a flat center section 103a and a first leg section 103b extending gener ally laterally from the upper end center section and bent generally perpendicular to the plane of the center section 103a. A second leg section 103c extends laterally from and is bent generally perpendicular to the lower end of the flat center section 103a.
The upper legs 101b and 103b and the lower legs 101c and 103c extend from opposite sides of the respective center sections 101a and 103a of the neutral bus bar 101 and the line bus bar 103 so that when the two bus bars are placed side by side the flat upper leg sections 101b and 103b, and the flat lower leg sections 101c and 103c, are in spaced, flat confronting relation. The upper leg sections 101b and 103b extend through the central aperture 105 of the toroidal coil 97 while the leg sections 101c and 103c extend through the central aperture 107 in the toroidal coil 99.
__ 210~~18 The crimp 101d on the terminal portion 101c' of the lower leg 101c on the neutral bus bar 101 secures this bus bar to the neutral pigtail 11. The crimp 101d is bent at an angle to the terminal portion 101c' of the lower leg 101c so that the pigtail is lead directly from the crimp to the opening 111 in the housing 3. The upper leg 101b of the neutral conductor 101 is connected by an insulated lead 110 to a tang 113 which is secured to the load neutral terminal 7. This upper end of the neutral bus bar 101 is also connected by the lead 112 to the printed circuit board 91.
The lower end of the line bus bar 103 is connected by the flexible conductor 67 to the bimetal 61 and is also connected by a lead 114 to the printed circuit board 91.
The upper end of the line bus bar 103 is connected through an opening in the central panel 23 to the tang 69 leading to the load terminal 5. The windings on the toroidal sensing coils 97 and 99 form the secondaries of the sensing transformers.
In an exemplary embodiment of the invention, the neutral bus bar 101 and line bus bar 103 are formed from copper sheet material having a thickness of 0.047 inches (1.2 mm). The center sections are .135 inches (3.4 mm) wide and the legs are .125 inches (3.175 mm) wide. With these bus bars, the circuit breaker 1 has a rated current of 50 amperes. With the prior art insulated wire used as the neutral and line conductors for the sensing transform-ers, the 0.220 inch (5.59 mm) diameter of the central apertures 105 and 107 of the sensing coils limit the rated current of the circuit breaker 1 to 30 amps using 10 gauge twisted wire. Thus, the bus bars 101 and 103 allow the rating of the ground fault circuit breaker to be increased without major modification to the circuit breaker struc-ture.
The neutral and line bus bars 101 and 103 are electrically insulated from each other, and from surround-ing components by a one piece insulating barrier 235. The mo5~ts insulating barrier 235 comprises a pair of confronting C-shaped insulating members 237 and 239 in a common plane R
joined by linear sections 241 and 243. The C-shaped members 237 and 239 conform to the shape of the center portions 101a and 103a and the portions of the bent legs B
and C which are in the same plane as the center sections.
These C-shaped members 237 and 239 have edge extensions 245 and 247, respectively, which extend over the side edges of the conductors 101 and 103. The linear sections 241 and 243 join the C-shaped members 237 and 239 in the plane of the bottom edge extensions 245 and 247. These linear sections 241 and 243 are hinged at their connections 241A
and 243A with the C-shaped member 237 and at hinge connec-tions 241B and 243B at the connection with the C-shaped member 239. The linear sections 241 and 243 are also formed with score line 241C and 243C at their mid-points.
trippers 249 and 251 are molded into the edge extensions 245 and 247, respectively.
The insulating barrier 235 can be formed flat in a vacuum forming process. The linear sections 241 and 243 are then folded at the hinge lines 241a-b, 243a-b and score lines 241c and 243c to form projections 253 which extend transverse to the common plane of the C-shaped members 237 and 239 as shown in Figure 5. This also brings the C
shaped members 237 and 239 close together to the same spacing as the conductors 101 and 103. The projections 253 are then pressed between the facing depending legs 101B, 103B and 101C, 103C, respectively, with the C-shaped members 237 and 239 fitting down over the center sections 101A and 103A. The grippers 249 and 251 snap under the bottom surfaces of the conductors 101 and 103 to secure the insulating barrier 235 in place. A suitable material for the insulating barrier 235 is 0.010 inches or .25 thick polycarbonate.
An alternate form of the insulating barrier 257 is illustrated in Figure 6. In this embodiment, the insulat-ing barrier 257 is formed with the projections 259 and 261.
._ 210~~18 These projections 259 and 261 space the confronting C-shaped members 263 and 265 properly to snap over the conductors 101 and 103, without folding, as in the previ-ously described embodiment.
In operation, upon detection of a grounded load conductor or a grounded load neutral conductor through the toroids 97 or 99, the ground fault circuit 119 energizes a trip solenoid 123. Energization of the trip solenoid 123 results in extension of the solenoid plunger 127. A flag 129 secured to the plunger extends through a slot 131 in the center panel 25 and pushes the armature 71 to the right as viewed in Figure 2 to trip the circuit breaker thereby opening the separable contacts 29.
In order to allow for periodic verification of the operation of the circuitry, a test circuit is provided which includes the test switch 17, accessible from the outside of the housing 3 as seen in Figure 1. More specif ically, a test wire 121 is connected between the neutral conductor 101 and the load conductor 103 by way of the test switch 139 of the test switch 17, which closes contacts 135 and 137, and is routed through the toroid 97 (Fig. 3) to induce a signal in the secondary winding T1 to simulate a ground fault condition. Upon actuation of the test button 139, a ground condition is simulated, resulting in a trip of the circuit breaker through energization of the trip solenoid 123.
The lower end of the neutral 101 is welded to the end of the pigtail 11 extending through an opening 111 in the housing 3 for connection to a panel neutral. The upper end of the neutral lead 1a1 is connected to the printed circuit board by a lead 112 and to a tang 113 leading to the load neutral terminal 7. The lower end of the line lead 103 is connected to the flexible conductor 67 leading from the bimetal 61 and by lead 114 to the printed circuit board, while the upper end is connected through an opening in the central panel 23 to the tang 69 leading to the load terminal 5. The windings T1 and T2 on the toroidal sensing coils 97 and 99 form the secondaries of the transformers.
The schematic diagram of the circuit 119 of the ground fault detector which is mounted on the printed circuit board.91 is. illustrated in Figure 7. The circuitry 119 includes the sensing toroids 97 and 99 with secondary windings T1 and T2, respectively. As previously discussed, the line conductors 103 as well as the neutral conductor 101, are routed through the toroids 97 and 99. Additional-1y, a test conductor 121 is routed through the upper toroid 97.
The toroid 97 is used for sensing ground faults.
During normal conditions, the magnetic fields generated by the conductor 103 amd the neutral conductor 101 cancel and therefore do not induce a voltage on the secondary winding T1 of the thyroid 97. However, during a ground fault condition, there will be a resultant magnetic field which will induce a voltage in the secondary winding T1 which, in turn, will energizE: a trip solenoid 123 by way of a ground fault interrupter integrated circuit IC1, as discussed below.
The toroi.d 99 is used in conjunction with the toroid 97 fo:r sensing a grounded neutral condition. As discussed in Linear Integrated Circuits 1989 by Raytheon Corporation, Section 10 on pages 10-16 through 10-21, a grounded nE~utral will close a magnetic path between the toroids 97 and 99. The resultatant AC coupling closes a feedback path around an operational amplifier in the IC1 causing the operational amplifier to oscillate. When the peaks of the oscillation voltage exceed an CR trigger comparator threshold within the IC1, the IC1 output will go high. Circuitry for detecting a grounded neutral condition is also disclosed in United States Reissue Patent No.
30,678.
'1'L1C secondary windings T1 and T2 of the toroids 97 and 99, respectively, are applied to a low power ground fault interrupter integrated circuit IC1, such as a Raytheon RV4:145 or a TRC-10020 by Technology Research Corporation of Clearwater, Florida. More specifically, one side of the secondary winding T1 is applied to pin 3 of the integrated circuit IC1. The other side of the secondary winding T1 is applied to pin 1 of the IC1 by way of the resistor R1 and serially coupled capacitor C1. A resistor R2 is connected between pins 1 and 8 of the integrated circuit IC1. The resistors R1 and R2 determine an amplifi-cation factor for an operational amplifier within the integrated circuit IC1. Exemplary values for the resistors R1 and R2 are 150 ohms and 1 megohm, respectively. The capacitor C1 which may be, for example, 15 microfarads acts as a coupling capacitor. A noise capacitor C2, for exam-ple, 0.01 microfarads is connected between pins 1 and 2 of the integrated circuit IC1.
One side of the secondary winding T2 is connected to the secondary winding T1 that is connected to pin 3 of the integrated circuit IC1. The other side of the second-ary winding T2 is connected to a tuning capacitor C3, for example, 1 microfarad. The other side of the tuning capacitor C3 is connected to the resistor R2, pins 7 and 8 of the integrated circuit IC1 as well as to a noise capaci-tor C4, for example, 0.01 microfarads. The other side of the noise capacitor C4 is connected to pin 4 of the inte-grated circuit IC1.
The winding of the trip solenoid 123 is connected on one end to the line conductor 103 with the other end connected to a full wave rectifier, generally indicated by the reference numeral 125, and including the diodes D1, D2, D3 and D4. The do output of the full wave rectifier 125 is connected across a silicon controlled rectifier SCR 1.
The gate terminal of the silicon controlled rectifier SCR
1 is connected to pin 5 of the integrated circuit IC1. A
noise capacitor C5, for example 6.8 microfarads is connect-ed between the gate terminal of the silicon controlled rectifier SCR 1 an pin 4 of the integrated circuit IC1 to prevent spurious triggering of the silicon controlled rectifier SCR 1.
A resistor R4, for example 30 kilohms, is con-nected between full wave rectifier 132 and pin 6 of the integrated c:ircuiit IC1. This resistor limits the current to the :shunt regulator within the integrated circuit IC1. Surge protective devices, such as the varistors RV:L and :RV2 are used to protect the circuit from overvoltage.
In operai:ion, upon detection of a grounded load conductor or a grounded load neutral conductor by the toroids 97 or 99, a voltage is induced in the secondary windings T1 <~nd T2. This voltage, in turn, is applied to the integrated circuit IC1. During such conditions, pin 5 of the integrated circuit IC1 enables the gate terminal to fire the silicon controlled rectifier SCR 1, which, in turn, energi2;es thE; trip solenoid 123. Energization of the trip solenoid 123 results in extension of the solenoid plunger 127. A flag 129 secured to the plunger extends through a slot 131. in the center panel 25 and pushes the armature 71 t:o the right as viewed in Figure 2 to trip the circuit breal~:er thereby opening the separable contacts 29.
In order to allow for periodic verification of the operation of the circuitry, a test circuit 132 is provided which includes thc~ test switch 17, accessible from the outside of the hour>ing 3 as seen in Figure 1. More specif ically, the test wire 121 is connected between the load neutral conductor 101 and the load conductor 103 by way of the test switch 17, and a resistor R3, for example 15 kilohms, and is routed through the toroid 97 (Fig. 3) to induce a signal in the secondary winding T1 to simulate a ground fault condii~ion. Upon actuation of the test button 17, a ground condition is simulated, resulting in a trip of the circuit breaker through energization of the trip solenoid 123.
Referring to Figures 3, 8 and 9, the test switch 17 includes a. fixed contact 135, a movable contact 137 and a test button 139. The fixed contact 135 and the movable contact 137 each comprise an electrically conductive metallic strip, suc:h as a copper strip. The metallic strip of the fixed contact 135 has a base section 141 which is secured alone a side edge 143 to the printed circuit board by a latera:Lly e:~tending projection 145 which extends ._ through the printed circuit board and is soldered in place on the back of the printed circuit board. The solder joint 146 also electrically connects the fixed contact 135 to a lead trace 147 in the test circuit of the printed circuit board. The fixed contact has a terminal section 148 cantilevered laterally from the end of the base section 141. The movable contact 137 similarly has a base section 149 and a terminal section 151 and is similarly secured along the side edge of the base section 149 to the printed circuit board. The fixed and movable contacts 135 and 137 are nested in spaced relation with the base portions substantially parallel. The terminal section 151 of the movable contact 137 extends at substantially a right angle to the base section 149, while the angle between the base section and terminal section of the fixed contact is slightly greater than a right angles so that the terminal section 148 angles slightly toward the terminal section 151 of the movable contact 137.
The test button 139 includes an enlarged head portion 153 which is received in a recess 155 in an upward ly extending bass 157 molded into the housing 3. A stem 159 on the underside of the head 153 extends through a guide opening 161 in the housing 3 and terminates and an enlarged terminal portion 163. The terminal section 151 of the movable contact 137, which is resiliently deformable, being made of copper, bears against the terminal portion 163 and biases the button to the full upward or unactuated position shown in Figure 3. The button 139 is retained by the terminal portion 163 which bears against the portion of the housing 3 forming the guide opening 161. With the test switch 17 in its unactuated position, the test circuit 119 is open circuited. When the ground fault detector is to be tested, the test button 139 is depressed thereby resilient-ly deforming the movable contact 137 to bring it into electrical contact with the fixed contact 135 to complete the test circuit as shown in Figure 6.
._ ~10~~18 While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alterna-tives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustra-tive only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.
Claims (8)
1. A circuit breaker including a power circuit and neutral circuit; separable power contacts connected in said power circuit; an operating mechanism for opening and closing said separable power contacts; a trip mechanism responsive to selected current conditions in said power circuit for tripping said operating mechanism to open said separable power contacts; characterized by a ground fault interrupt including: a pair of toroidal sensing coils laterally spaced from each other in a common plane each sensing coil having a coil end face and a central aperture transverse to said coil end face, said coil end face of each sensing coil being in said common plane; and a pair of flat bus bars each having a flat center section with its widest portion laying flat and in a plane extending parallel to said common plane of said coil end face of each sensing coil and between said toroidal sensing coils and offset laterally from the flat center section of the other bus bar, and flat leg sections extending generally laterally from each end of the center section and bent to extend one through each of said aperture of said toroidal sensing coils generally transverse to said common plane, and means connecting one of said flat bus bars in said power circuit and the other of said flat bus bars in said neutral circuit, and actuating means connected to said sensing coils and operative to actuate said trip mechanism in response to a ground fault in either said power circuit or said neutral circuit.
2. The circuit breaker of claim 1 wherein one leg section of said other flat bus bar connected in said neutral circuit has a terminal portion with a crimped end which secures said other bus bar in said neutral circuit.
3. The circuit breaker of claim 2 wherein said terminal portion of said other flat bus bar is bent into a plane substantially parallel to said common plane.
4. The circuit breaker of claim 1 wherein said flat bus bar: comprise a pair of confronting C-shaped flat bus bars with facing, depending end portions at least one of which from each bus bar extends through said at least one toroidal ground fault sensing coil; and an insulating barrier comprising a pair of confronting C-shaped insulat-ing members conforming to the shape of said flat C-shaped bus bars and joined by a pair of projections which extend between and electrically insulate said facing, depending end portions.
5. The circuit breaker of claim 4 wherein said projections comprise linear sections formed substantially in a common plane with said C-shaped insulating members and foldable to projects generally transverse to said common plane between said facing, depending end portions of said C-shaped bus bars.
6. The circuit breaker of claim 1 further characterized by a ground fault test circuit mounted on a printed circuit board, including test apparatus including a fixed contact member mounted on said printed circuit board and electrically connected to said ground fault test circuit; a resiliently deformable movable contact member supported at a first end directly by said printed circuit board and electrically connected to said ground fault test circuit; and a test button biased to an off position by said resiliently deformable movable contact member and depressible to resiliently deform said resiliently deform-able movable contacts member to contact said fixed contact member to complete said ground fault test circuit.
7. The circuit breaker of claim 6 wherein said resiliently deformable movable contact member comprises a first electrically conductive metallic strip secured along a side edge at said first end to said printed circuit board.
8. The circuit breaker of claim 7 wherein said first electrically conductive metallic strip of, said resiliently deformable movable contact member has a base section extending from said first end, and a terminal section bent at an angle to said first section and terminating in a free end which contacts said fixed contact member when said test button is depressed.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/943,796 US5291165A (en) | 1992-09-11 | 1992-09-11 | Insulating barriers for circuit breaker bus bars and a ground fault circuit breaker incorporating same |
| US07/943,670 US5293142A (en) | 1992-09-11 | 1992-09-11 | Ground fault circuit breaker with flat bus bars for sensing coils |
| US943,801 | 1992-09-11 | ||
| US07/943,801 US5293522A (en) | 1992-09-11 | 1992-09-11 | Ground fault circuit breaker with test spring/contacts directly mounted to test circuit of printed circuit board |
| US943,796 | 1992-09-11 | ||
| US943,670 | 1992-09-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2105918A1 CA2105918A1 (en) | 1994-03-12 |
| CA2105918C true CA2105918C (en) | 2002-12-17 |
Family
ID=27420707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2105918 Expired - Fee Related CA2105918C (en) | 1992-09-11 | 1993-09-10 | Solid copper bus shunt through ground fault circuit breaker electronic |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU661185B2 (en) |
| BR (1) | BR9303743A (en) |
| CA (1) | CA2105918C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2422957B (en) * | 2005-04-20 | 2007-10-03 | Boeing Co | Circuit protection devices having an integral barrier with grounding provision |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109390187B (en) * | 2017-08-09 | 2020-09-04 | 施耐德电气工业公司 | Earth leakage circuit breaker |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4081852A (en) * | 1974-10-03 | 1978-03-28 | Westinghouse Electric Corporation | Ground fault circuit breaker |
| US3931601A (en) * | 1974-11-27 | 1976-01-06 | Amf Incorporated | Receptacle device ground fault circuit interrupter |
-
1993
- 1993-08-17 AU AU44724/93A patent/AU661185B2/en not_active Ceased
- 1993-09-09 BR BR9303743A patent/BR9303743A/en not_active IP Right Cessation
- 1993-09-10 CA CA 2105918 patent/CA2105918C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2422957B (en) * | 2005-04-20 | 2007-10-03 | Boeing Co | Circuit protection devices having an integral barrier with grounding provision |
Also Published As
| Publication number | Publication date |
|---|---|
| BR9303743A (en) | 1994-03-29 |
| CA2105918A1 (en) | 1994-03-12 |
| AU661185B2 (en) | 1995-07-13 |
| AU4472493A (en) | 1994-03-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |