A molded case circuit breaker configured to protect its ports and cables is provided. The molded case circuit breaker comprises an electronic trip unit (ETU) including communication ports or a thermomagnetic trip unit (TMTU). The molded case circuit breaker further comprises a terminal cover configured to pass cables that connect to the communication ports of the ETU and pass the cables over lugs without touching the lugs. The molded case circuit breaker further comprises a cable box cover that protects the cables of the ETU from external harm. The terminal cover including an emboss fixture having emboss guides for alignment and fixing of the cable box cover. The electronic trip unit (ETU) or the thermomagnetic trip unit (TMTU) and the cable box cover are assembled with one or more screws. The cable box cover is prevented from falling after the one or more screws are taken out from the terminal cover regardless of how the circuit breaker is mounted.

A molded case circuit breaker configured to protect its ports and cables is provided. The molded case circuit breaker comprises an electronic trip unit (ETU) including communication ports or a thermomagnetic trip unit (TMTU). The molded case circuit breaker further comprises a terminal cover configured to pass cables that connect to the communication ports of the ETU and pass the cables over lugs without touching the lugs. The molded case circuit breaker further comprises a cable box cover that protects the cables of the ETU from external harm. The terminal cover including an emboss fixture having emboss guides for alignment and fixing of the cable box cover. The electronic trip unit (ETU) or the thermomagnetic trip unit (TMTU) and the cable box cover are assembled with one or more screws. The cable box cover is prevented from falling after the one or more screws are taken out from the terminal cover regardless of how the circuit breaker is mounted.

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 method for adjusting a magnetic release mechanism includes steps: a first measurement of the present release current I of the magnetic release mechanism is carried out, a decision is made as to whether an adjustment step is performed, a start-adjustment current I.sub.J0 is selected, a second measurement of the present release current I of the magnetic release mechanism is carried out, a decision is made as to whether an adjustment step is performed and that in the event that an adjustment step is necessary, a selection of a certain differential amount ΔI.sub.J takes place, partial demagnetisation of the permanent magnet is carried out in a further adjustment step with the adjustment current I.sub.J formed in this way and the steps are carried out in succession until the release current I measured lies within a specified range between I.sub.TARGET.sub._.sub.min and I.sub.TARGET.sub._.sub.max.

A circuit interruption device (e.g., a molded case circuit breaker) includes at least one set of contacts, a contact actuator mechanism configured to open the at least one set of contacts and a trip control circuit configured to cause the contact actuator mechanism to open the at least one set of contacts responsive to a condition satisfying a first trip criterion and to apply a second trip criterion (e.g., a lower current level trip threshold) responsive to the opening of the at least one set of contacts. The trip control circuit may be configured to apply the second trip criterion after a succeeding closure of the at least one set of contacts. The trip control circuit may be further configured to return to application of the first trip criterion after lapse of a predetermined interval following the succeeding closure of the at least one set of contacts.

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.

A circuit breaker includes at least one moveable contact. The moveable electrode is operably connected to a Thomson coil actuator that can separate and open the contacts of the circuit breaker. A sensor senses current or voltage in the circuit breaker. When a condition exists that triggers an opening action, a controller will use select a current level to apply to the Thomson coil actuator. The selected current level will vary based on the sensed current or voltage level. The controller will cause a driver to apply the selected current level to the Thomson coil actuator, and it will cause the contacts to separate and open. If the circuit breaker is a vacuum interrupter, the vacuum interrupter may employ a multi-section bellows in which each section has unique structural characteristics as compared to the other sections, so that different sections will dominate as the Thomson coil's speed of operation varies.

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.

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.

A circuit breaker includes at least one moveable contact. The moveable electrode is operably connected to a Thomson coil actuator that can separate and open the contacts of the circuit breaker. A sensor senses current or voltage in the circuit breaker. When a condition exists that triggers an opening action, a controller will use select a current level to apply to the Thomson coil actuator. The selected current level will vary based on the sensed current or voltage level. The controller will cause a driver to apply the selected current level to the Thomson coil actuator, and it will cause the contacts to separate and open. If the circuit breaker is a vacuum interrupter, the vacuum interrupter may employ a multi-section bellows in which each section has unique structural characteristics as compared to the other sections, so that different sections will dominate as the Thomson coil's speed of operation varies.