Abstract: A modular circuit breaker system includes a plurality of modules mounted side-by-side. The modules include electrical terminals for connection to live and neutral conductors of an electrical supply. Rigid metallic conductors extend between the modules for connecting electrical circuitry of one module to the electrical circuitry of the other module. Each conductor is removably engaged with electrical contacts mounted within the respective modules.

Abstract: An electro-magnetic operating device 10 for a circuit breaker includes a coil 12 defining a cavity 14. A stator frame 20 which includes a pole piece 18 is arranged about the coil 12. A tube, which is closed off at one end by an end wall and at an opposed end by the pole piece 18 is arranged in the cavity 14. The tube 24 carries a core 22 therein. The plunger 22 is urged away from the pole piece 18 by a coil spring 28 arranged in the tube 26. The spring 28 is selected so that, when a load current of 100% is carried in the coil 12, the electro-magnetic force imparted to the core 18 exceeds the spring force imparted by the spring 28 to the core 22.

Abstract: A modular housing for a circuit breaker has first and second opposed side panels which engage one another at respective upper and lower edges defined by transversely extending flanges. The mated flanges define the upper and lower edges of the housing. When assembled, the side panels define an enclosure with front and rear openings, with grooves on the inner edges of the openings which receive tongues of respective modular front and rear panels of the circuit breaker housing. The front panel has an opening through which an operating lever protrudes when the housing is assembled, and the operating lever pivots on formations on the inner surfaces of the side panels. The modular construction of the circuit breaker housing allows different front and rear panels to be fitted to a common shell. For example, a range of circuit breakers having different operating handles and different terminal configurations can be provided at a relatively low cost.

Abstract: A method of fitting an overload coil for a circuit breaker onto a bobbin assembly. The overload coil is pre-formed into a helical coil with a pair of terminals and a coil sub-assembly is formed by attaching electrical leads to the terminals of the coil. Separate base and top halves of a split bobbin are assembled so that the pre-formed coil of the coil sub-assembly is held captive therebetween. A sensing tube is fitted through an aperture extending axially through the assembled split bobbin, and the sensing tube is mounted onto a magnetic cradle. Different top halves, such as a voltage coil top half and a high inrush top half may be fitted into a common base half. The invention extends to a bobbin assembly for a circuit breaker, as well as to an overload coil sub-assembly.

Abstract: A circuit breaker mechanism is provided with a U-shaped tripping lever which has a base and first and second parallel legs. The tripping lever is arranged around the magnetic frame of the circuit breaker and is mounted on pivot points which coincide with the pivot axis of the circuit breaker armature. On one leg is an outwardly extending projection, while on the other leg is a complemental cavity. A number of circuit breakers can be assembled side-by-side, with the projection on the tripping lever of a first circuit breaker engaging the cavity in the tripping lever of an adjacent circuit breaker. Thus, when one circuit breaker is tripped, the others are tripped together with it.

Abstract: An electro-magnetic operating device 10 for a circuit breaker includes a coil 12 which defines a cavity 14. A pair of elements 34, 44 are slidably arranged within the cavity 14, a first element 34 being operable to cause a time delay tripping of the circuit breaker and a second element 34 being operable to cause a substantially instantaneous tripping of the circuit breaker. A first pole piece 22 is associated with the first element. A linkage 64 is carried by the second element 44 for linking the second element to a moving contact carrier 66 of the circuit breaker. A frame 18, which defines a magnetic path, is arranged about at least a part of the coil 12, the magnetic frame 18 defining a second pole piece 40 which is aligned with the first pole piece 22. The first pole piece 22 and the elements 34, 44 are displaceable towards the second pole piece 40 to effect tripping of the circuit breaker.

Abstract: A circuit breaker actuating mechanism has a magnetic frame and a load coil, with a magnetic pole piece which is aligned with the axis of the coil. An elongate L-shaped armature pivots on the magnetic frame and has a head which moves transversely relative to the axis of the coil towards the pole piece. The pole piece is typically circular in section, and the head of the armature has a circular recess which matches the shape of the pole piece. The head of the armature has a pair of projections which extend relatively close to the pole piece when the armature is in a retracted position, increasing the initial attractive force between the pole piece and the armature. The mechanism is relatively simple and economical to manufacture, and offers an improved pull-in force.

Abstract: A shunt trip device includes an armature 18 pivotally mounted on a frame 12 of a ferro-magnetic material. A "U"-shaped member 20 is mounted on the frame 12 via a spacer 30 of a non-magnetic material. The member 20 and a portion of a post 16 of the frame 12 and the armature 18 define a first magnetic circuit. A limb 22 and a bridge portion 26 of the member 20 together with a part 14.1 and the post 16 of the frame and the armature 18 define a second magnetic circuit. A limb 24 and the bridge 26 of the member 20 together with the part 14.1 and the post 16 of the frame 12 and that portion of the armature 18 between the post 16 and the limb 24 define a third magnetic circuit. A coil 34 is carried on the limb 22 of the member 20 and permanent magnetic 22 is sandwiched between the portion 26 of the member 20 and the part 14.1 of the frame 12.

Abstract: An electro-magnetically operable device 12 for a circuit breaker 10 comprises a coil 13 that defines a cavity. A first plunger 14 and a second plunger 16 are located within the cavity, adjacent one another. The first plunger 14 is housed in a sealed canister 18 which is filled with a damping liquid. The plunger 14 is displaceable within the canister 18 in a damped manner. The second plunger 16 is also displaceable within the cavity and movement thereof is guided by an open tube 20. The first plunger 14 and the second plunger 16 are urged away from a pole piece 30 of the device 12 via helical springs 32 and 34, respectively.

Abstract: A current monitoring assembly 12 of a circuit breaker includes a coil 16, a tube 18 slidably mounted in the coil 16, a core 20 slidably housed within the tube 18, a first pole piece 22 mounted on an end of the tube 18 and an "O"-shaped magnetic frame 24 having a second pole piece 26 aligned with the first pole piece 22. A retarding fluid is contained within the tube 18 and a core spring 46 is arranged intermediate an end of the core 20 and the pole piece 22.

Abstract: The invention relates to a regulated DC power supply circuit comprising a full wave rectification stage for rectifying an AC input and a regulating stage for regulating an output voltage from the rectification stage. The regulating stage has a primary voltage regulating circuit and a secondary voltage regulating circuit. The primary voltage regulating circuit includes a series pass element, such as a MOSFET device, connected to operate continuously in source-follower mode. A primary voltage reference element, such as a zener diode, provides a gate reference for the series pass element. The secondary voltage regulating circuit is cascaded to the primary voltage regulating circuit in a voltage sharing configuration. The power supply circuit is therefore capable of handling input voltages over 1 kV, which exceed the maximum voltage rating of the MOSFET device. The invention extends to a DC voltage regulator, which includes the regulating stage without the rectification stage.

Abstract: An electro-magnetic shunt trip device has a pair of aligned plungers 10,24. A first plunger 19 acts on an operating member 20 which is pivotal and connected to a spring 18. The second plunger 24 is manually displaceable. A further spring 26 is located between the plungers. The plungers are part of a magnetic circuit, with a magnetic field being generated by a permanent magnet 30 and an electro-magnet 32. The permanent magnet and the electro-magnet generate fields of opposite polarity. If there is no current in the electro-magnet, the field provided by the electro-magnet will be sufficiently strong to hold the two plungers together. The spring 18 acting on the operating member will cause it and the plungers to move, so that the operating member is in a non-tripping position.

Abstract: A mounting frame is provided for components of a circuit breaker. The frame is of metal and is designed so that it carries current and is not merely for supporting the components. The frame has a terminal portion, a field generating portion, pole piece defining portions, a reverse arc runner, a support post for a bi-metal strip, a latching projection for an armature, guide surfaces for the armature and a pivot pin for an operating handle. The invention further provides a circuit breaker which utilizes the frame and to a circuit breaker which uses a coil of varying resistance, in comparison with the constant resistance of a path between a terminal and a bi-metal strip, to vary the magnetic tripping characteristic of breaker.

Abstract: A circuit breaker mechanism has an armature component that is slidably displaceable between latched and tripping positions. The armature is connected to a moving contact carrier that is pivotally connected to an operating handle that is also pivotal. The armature is connected to the carrier by a spring. The armature has a latching formation which engages a projection. When tripped,the armature is slightly pivoted to clear the projection.