The current transformer includes a magnetic circuit made of magnetic material that is intended to be placed around a primary conductor, and a secondary winding that is wound onto a portion of the magnetic circuit in order to deliver a secondary current to processing circuits. In this current transformer the magnetic circuit includes at least one device for varying the magnetization of a portion of the magnetic circuit according to the temperature in order to limit or to decrease the magnetic flux in the magnetic circuit when the temperature of the magnetic circuit increases. The protection device and the electrical circuit breaker include such a transformer.

An electromagnetic trip unit, wherein: the electromagnetic trip unit includes a movable core, an upper static core and a lower static core; the movable core can move relative to the upper static core and the lower static core in the upper static core and the lower static core; a movable core body end of a movable core body of the movable core faces and approaches the lower static core end of the lower static core, when the electromagnetic trip unit is not released, a first magnetic field air gap is formed between the movable core body end and the lower static core end; the movable core body of the movable core is also provided with a movable core body step, when the electromagnetic trip unit is not released, a second magnetic field air gap is formed between the movable core body step and the lower static core end.

A direct-acting electromagnetic trip device including a housing, and a regulation mechanism, a linkage mechanism, an electromagnetic system and a trip mechanism which are arranged in the housing. The regulation mechanism is connected with the linkage mechanism, the linkage mechanism is connected with one end of an iron core of the electromagnetic system, and the linkage mechanism is connected with the trip mechanism at the same time. The regulation mechanism includes a rotary knob and a regulation rod, wherein the rotary knob is abutted against and engaged with the regulation rod, and the regulation rod is abutted against and engaged with the linkage mechanism. The electromagnetic system further includes an elastic element that pushes the iron core to allow the linkage mechanism to be abutted against the regulation rod and allow the rotary knob to be abutted against the regulation rod.

An apparatus having a conductor passing through a magnetic yoke and is mounted on the bracket, in which the magnetic yoke is fixed on the bracket as well. Above the conductor, a shaft is mounted on the top of the bracket. A push rod is mounted on the shaft and rotates with the shaft about the bracket. An armature, spaced apart from the magnetic yoke, is fixed on the push rod. Adjusting mechanisms are mounted on both sides of the shaft between the push rod and the bracket. Within the adjusting mechanism, a torsion spring is around the shaft. An adjusting rod is provided with a plurality of adjusting surfaces which makes contact with the adjusting mechanism. A spring force of the torsion spring enables the push rod to rotate towards a direction which makes the armature and the magnetic yoke separate.

A short-circuit protection action current adjusting method and a device thereof for a multi-pole electromagnetic release. An electromagnetic system includes an auxiliary static iron core, a second static iron core, a coil, a reset spring and a dynamic iron core; at an initial position, a first gap is formed between the auxiliary static iron core and the dynamic iron core, a second gap is formed between the dynamic iron core and the second static iron core, and the thickness of the second gap changes in the same direction along with the size variation of a release threshold; the elastic force of the reset spring changes oppositely along with the size variation of the release threshold; when a release current value is adjusted from large to small, the coil energy reduces in a quadratic relationship mode along with flowing currents and meanwhile the electromagnetic attraction between the dynamic iron core and the second static iron core is increased in a quadratic relationship mode, which is in inverse proportion to reduction of the thickness of the second gap. According to the short-circuit protection action current adjusting method and device thereof for the multi-pole electromagnetic release, adjustment of the release current value and electromagnetic attraction required by actions of the dynamic iron core are in a linear fixed corresponding relationship due to automatically achieved balance between two quadratic functions, and adjustment of the release threshold through the user is convenient, reliable and stable.

Disclosed embodiments include an instant trip mechanism for a molded case circuit breaker. In some embodiments, the mechanism includes an adjustment dial to set a current for an instant trip operation; an instant bar provided with an upper portion contactable with the adjustment dial, a shaft portion serving as a rotation shaft, and a lower extending portion downwardly extending from the shaft portion; an electromagnet unit to generate a magnetic attraction force that is proportional to an amount of current flowing on the circuit; an armature rotatable with a lower end portion supported by a shaft, and attracted toward the electromagnet unit by the magnetic attraction force; and a spring for applying to the armature a load varying in a direction of the armature getting away from the electromagnet unit.

Disclosed is a molded case circuit breaker including a case configured to accommodate an element for trip, an upper cover detachable attached to the case, a dial configured to include a fixing plate, which is provided to protrude along an outer circumference surface thereof, and a first stopper disposed under the fixing plate, a crossbar moved by the dial, a first dial fitting hole provided in the upper cover for the dial to be fitted into the first dial fitting hole, and a dial rotation adjusting unit provided in the first dial fitting hole and fitted between the fixing plate and the first stopper to guide a rotation of the dial, the dial rotation adjusting unit including a plurality of fitting grooves arranged at certain intervals. The first stopper is fitted into and fixed to the plurality of fitting grooves according to the rotation of the dial.

Methods, apparatus, and systems are provided for a selectivity device for a circuit breaker. The invention includes a modular assembly adapted to be coupled to a load conductor assembly. The modular assembly includes a tripping plunger including a cam surface adapted to interact with a breaker tripping mechanism; an armature coupled to the tripping plunger; a yoke adapted to generate a magnetic field in response to an electric current in the load conductor assembly and disposed to apply a magnetic force proportionate to the electric current on the armature; and a spring assembly adapted to counter-balance the magnetic force up to a predefined tripping current in the load conductor assembly. Numerous additional aspects are disclosed.

A short-circuit protection action current adjusting method and a device thereof for a multi-pole electromagnetic release. An electromagnetic system includes an auxiliary static iron core, a second static iron core, a coil, a reset spring and a dynamic iron core; at an initial position, a first gap is formed between the auxiliary static iron core and the dynamic iron core, a second gap is formed between the dynamic iron core and the second static iron core, and the thickness of the second gap changes in the same direction along with the size variation of a release threshold; the elastic force of the reset spring changes oppositely along with the size variation of the release threshold; when a release current value is adjusted from large to small, the coil energy reduces in a quadratic relationship mode along with flowing currents and meanwhile the electromagnetic attraction between the dynamic iron core and the second static iron core is increased in a quadratic relationship mode, which is in inverse proportion to reduction of the thickness of the second gap. According to the short-circuit protection action current adjusting method and device thereof for the multi-pole electromagnetic release, adjustment of the release current value and electromagnetic attraction required by actions of the dynamic iron core are in a linear fixed corresponding relationship due to automatically achieved balance between two quadratic functions, and adjustment of the release threshold through the user is convenient, reliable and stable.

A circuit breaker including an adjustable instantaneous trip level. Adjustable instantaneous trip level can be applied to a one-pole and/or two-pole circuit breakers including a thermal and magnetic mechanism, including AFCI, CAFCI, and/or GFCI constructions. The circuit breaker includes a magnet position adjustment mechanism allowing an operator to adjust the instantaneous trip level to a desired setting, such as between about 5 to 10 times the handle rating. The design also allows for alternate magnets to be used for either an increased or decreased instantaneous settings as desired. In two-pole circuit breakers, the instantaneous trip level can be set independently for each mechanism pole. Multi-pole circuit breakers and methods of adjusting instantaneous trip level are provided, as are other aspects.