Abstract: A circuit breaker with overload and short-circuit protection functions for a motor, on which is mounted a thermally actuated overload tripping device including an adjustment dial to set a value corresponding to a rated current value of the motor on a scale. The dial has a standard setting pointer mark and a correction setting pointer mark side-by-side along a perimeter. The standard setting pointer mark applies to using the circuit breaker as a single item. The correction setting pointer mark applies to using a number of circuit breakers arranged in a line in close contact with each other. By setting a mark selected according to the arrangement of the circuit breaker at the rated current value, the steady state current value of the tripping device can be adequately set to correspond to the rated current value of the motor.

Abstract: A circuit breaker with overload and short-circuit protection functions for a motor, on which is mounted a thermally actuated overload tripping device including an adjustment dial to set a value corresponding to a rated current value of the motor on a scale. The dial has a standard setting pointer mark and a correction setting pointer mark side-by-side along a perimeter. The standard setting pointer mark applies to using the circuit breaker as a single item. The correction setting pointer mark applies to using a number of circuit breakers arranged in a line in close contact with each other. By setting a mark selected according to the arrangement of the circuit breaker at the rated current value, the steady state current value of the tripping device can be adequately set to correspond to the rated current value of the motor.

Abstract: A circuit breaker includes terminals with screws on a power supply side and a load side disposed at a front end section and a rear end section of a main body case containing a current interrupting unit and a switching mechanism. A terminal cover is detachably attached onto the main body case at a position corresponding to the terminals on at least one of the power supply side and the load side. A terminal cover attaching surface is formed on an upper surface on the power supply side and/or the load side of the main body case. The terminal cover is inserted while sliding on the attaching surface from a front end, so that the terminal cover is attached to the main body case with a snap-fit coupling unit at an assembling position.

Abstract: A circuit breaker includes terminals with screws on a power supply side and a load side disposed at a front end section and a rear end section of a main body case containing a current interrupting unit and a switching mechanism. A terminal cover is detachably attached onto the main body case at a position corresponding to the terminals on at least one of the power supply side and the load side. A terminal cover attaching surface is formed on an upper surface on the power supply side and/or the load side of the main body case. The terminal cover is inserted while sliding on the attaching surface from a front end, so that the terminal cover is attached to the main body case with a snap-fit coupling unit at an assembling position.

Abstract: An overload/open-phase tripping device for a circuit breaker includes a plurality of bimetallic elements arranged in a row; a differential shifter mechanism; and a tripping lever for transmitting a force applied by the differential shifter mechanism to a switching mechanism. The differential shifter mechanism includes a push shifter having a plurality of operation ends; a pull shifter having a plurality of operation ends; and a differential lever disposed between the push shifter and the pull shifter. The differential lever is provided with an action end for applying the force to the tripping lever upon an overload, and an action end for applying the force to the tripping lever upon an open-phase. The two action ends face the tripping lever, and the action end for the open-phase is located at a position farther from the tripping lever than the action end for the overload.

Abstract: An overload/open-phase tripping device for a circuit breaker includes a plurality of bimetallic elements arranged in a row; a differential shifter mechanism; and a tripping lever for transmitting a force applied by the differential shifter mechanism to a switching mechanism. The differential shifter mechanism includes a push shifter having a plurality of operation ends; a pull shifter having a plurality of operation ends; and a differential lever disposed between the push shifter and the pull shifter. The differential lever is provided with an action end for applying the force to the tripping lever upon an overload, and an action end for applying the force to the tripping lever upon an open-phase. The two action ends face the tripping lever, and the action end for the open-phase is located at a position farther from the tripping lever than the action end for the overload.

Abstract: An overload tripping device includes a temperature-compensating bimetal operating as a tripping lever and interposed between an output lever of a differential shifter mechanism linked with a main bimetal and a latch receiver of an opening-and-closing mechanism section of a circuit breaker. The temperature-compensating bimetal has an intermediate portion journaled on a bimetal holder. An operating arm made of a light molding material is attached to a tip of the temperature-compensating bimetal so as to push the latch receiver. Additionally, a balance weight may be installed on the temperature-compensating bimetal to balance inertial moments on the opposite sides of the bimetal. Thus, the circuit breaker is prevented from being inadvertently tripped due to external stimulus.

Abstract: In an instantaneous-tripping circuit breaker, a heater-mounted main bimetal, a shifter of a differential shifter mechanism, and an adjustment dial of a thermal overload/open-phase tripping device are removed from a standard circuit breaker equipped with a breaking section, an opening and closing mechanism section, a thermal overload/open-phase tripping device, and an electromagnetic instantaneous tripping device in a case. Instead, a trip coil of the instantaneous tripping device is connected to a main circuit via a connection conductor of a low resistance, a test-tripping part is mounted in place of the shifter of the differential shifter mechanism, and the adjustment dial is replaced with a dummy dial. Accordingly, the standard circuit breaker is changed to an instantaneous-breaking circuit breaker.

Abstract: A thermal overload open-phase tripping device includes in a case bimetals corresponding to different phases; a differential shifter mechanism composed of a push shifter and a pull shifter, linked to operating ends of the bimetals, and an interlocking plate; and a compensating bimetal for transmitting output from the shifter mechanism to an opening and closing mechanism section of a breaker main body. The push and pull shifters are slidably supported to extend over interphase partition walls in the case, and a case cover is placed and held over the push and pull shifters. Rib-shaped projections projecting from an inner surface of the case cover and facing the top surfaces of the shifters are provided as shifter position guides to constrain inclination of the shifters moving in accordance with bending displacement of the bimetals to hold the shifters horizontally.

Abstract: In an instantaneous-tripping circuit breaker, a heater-mounted main bimetal, a shifter of a differential shifter mechanism, and an adjustment dial of a thermal overload/open-phase tripping device are removed from a standard circuit breaker equipped with a breaking section, an opening and closing mechanism section, a thermal overload/open-phase tripping device, and an electromagnetic instantaneous tripping device in a case. Instead, a trip coil of the instantaneous tripping device is connected to a main circuit via a connection conductor of a low resistance, a test-tripping part is mounted in place of the shifter of the differential shifter mechanism, and the adjustment dial is replaced with a dummy dial. Accordingly, the standard circuit breaker is changed to an instantaneous-breaking circuit breaker.

Abstract: An overload tripping device includes a temperature-compensating bimetal operating as a tripping lever and interposed between an output lever of a differential shifter mechanism linked with a main bimetal and a latch receiver of an opening-and-closing mechanism section of a circuit breaker. The temperature-compensating bimetal has an intermediate portion journaled on a bimetal holder. An operating arm made of a light molding material is attached to a tip of the temperature-compensating bimetal so as to push the latch receiver. Additionally, a balance weight may be installed on the temperature-compensating bimetal to balance inertial moments on the opposite sides of the bimetal. Thus, the circuit breaker is prevented from being inadvertently tripped due to external stimulus.

Abstract: In an overcurrent-tripping device for a circuit breaker, an electromagnet is used to open a movable contact shoe when a heavy current flows through a conduction path. A push rod is provided so as to contact the movable contact shoe. The electromagnet of the overcurrent-tripping device is located above the push rod so as to attract a movable iron core of the overcurrent-tripping device linearly along a moving direction of the push rod. When the heavy current such as a short-circuit current flows through the conduction path, the movable iron core is attracted to push the movable contact shoe via the push rod for rapid opening of the movable contact shoe. Thus, before a tripping operation of the opening-and-closing mechanism, the movable contact shoe is moved, so that the time required by the movable contact shoe for the opening operation is reduced.

Abstract: A switching mechanism for a circuit breaker includes a frame; a latch rotatably supported on the frame; a holder rotatably supported on the frame and having a movable contact; a handle lever rockably supported on the frame by lever shafts; a toggle link formed of first and second links rotationally connected by a toggle shaft; and a switching spring. A free end of the first link is rotatably connected to the latch, and a free end of the second link is rotatably connected to the holder. The first and second links generally overlap each other to reduce the movement range of the toggle link to miniaturize a switching mechanism. The switching spring is situated between the toggle shaft and the handle lever at a side opposite to a switching handle with respect to the lever shaft.

Abstract: A circuit breaker includes a current path for first and second contacts connected in series in an insulative container. When an overcurrent occurs by over load, the second contact is opened based on a command from a time delay trip portion of an overcurrent trip device. When a short-circuit current occurs, the first and second contacts are opened based on a command from an instantaneous trip portion of the overcurrent trip device. Since the first and second contacts are contained in a common container, the wiring works between the first contact and the second contact is unnecessary. Since the first and second contacts are opened in the instantaneous trip, interruption of a high short-circuit current is facilitated.