A large number of circuit protection devices (101) are copied mainly because of their relative mechanical and electronic simplicity. In the vast majority of cases the external appearance of most copies compares with a genuine product whilst their interior construction is somewhat different from the genuine design resulting usually in a much reduced performance and in some cases dangerous behaviour The proposed invention uses a fixture (100) at the point of sale to measure the time current characteristic (105,106,107) of a circuit protection device (109) or a plurality of circuit protection devices, and verify this characteristic against known data (110,111) for each individual circuit protection device. Once validated the overcurrent characteristic is re-calibrated (103,104,112) in a pre determined manner to enable each circuit protection device to function at its rated current.

A circuit breaker structure (3) having an adjustable magnetic trip unit characterized by an insulating housing (5) containing a circuit breaker mechanism (7) having separable contacts (21, 27), a trip unit (15) comprising a magnetic device respon­sive to overload current conditions, the magnetic device having an armature (105) and a calibrating screw (119) for calibrating an air gap between the armature and an associated magnet, the trip unit also including a cam for varying the tension of the spring (113) and the cam having spaced indexing indenta­tions and an associated ball (149) in the frame for rolling engagement with the cam surface and for seating in any indentation to provide positive settings of the spring tension.

The invention relates to a circuit interrupter including magnetically operable trip means for tripping the circuit interrupter open in response to overcurrents exceeding a predetermined value.

The trip means in each pole of the interrupter includes a trip-bar actuating lever (105) of unitary construction, a magnetic armature (113) disposed on the lever, and a magnetizable core (119) which cooperates with the armature to form a predetermined air gap (135) when the unitary lever is in a non-actuated position, and which core is disposed to be energized by said overcurrents, thereby to attract the armature and effect a trip-bar actuating movement of the lever, the arrangement being such that the air-gap defining surfaces of the armature and core are, and throughout movement of the lever remain, substantially parallel with respect to each other.

The novel arrangement permits precise calibration and adjustment over a wider range of trip currents and provides a predictably accurate response.

Ce déclencheur (10) est propre à être connecté à un disjoncteur et comprend un premier bloc (12) et un deuxième bloc (14). Le premier bloc (12) comprend un premier boîtier (16) et un organe de déclenchement (20) du disjoncteur accessible depuis l'extérieur du premier boîtier (16). Le deuxième bloc (14) comprend un deuxième boîtier (26) et au moins un organe de détection (28) d'un défaut électrique. Chaque organe de détection (28) est disposé à l'intérieur du deuxième boîtier (26) et comporte au moins un élément mobile (56) qui comprend une extrémité de contact (62) propre à être déplacé en direction de l'organe de déclenchement (20), lorsqu'il détecte un défaut électrique. Le premier bloc (12) et le deuxième bloc (14) sont deux blocs distincts l'un de l'autre et le premier boîtier (16) et le deuxième boîtier (26) sont propres à être mécaniquement assemblés l'un à l'autre dans une configuration assemblée du déclencheur (10). Chaque extrémité de contact (62) est propre à coopérer mécaniquement avec l'organe de déclenchement (20), de manière à ce que l'organe de déclenchement (20) soit apte à déclencher le disjoncteur en configuration assemblée du déclencheur, lorsque l'organe de détection (28) correspondant détecte un défaut électrique.

This concerns a molded case circuit breaker having separable main contacts and an operating mechanism utilized to cause the separable main contacts to open and close. A trip unit is provided to actuate the operating mechanism in desirable circumstances. The trip unit has a plunger and latch contained therein which is primarily responsible for latching the circuit breaker contacts open by way of the operating mechanism once a trip has occurred.