Abstract: Malfunction of an earth leakage breaker due to a lightning surge is prevented, and when a lightning arrester is short-circuited and damaged by a high-level lightning surge, a power supply short circuit is prevented. A contact 41, an overcurrent detector section 43, and a zero phase current transformer 44 are disposed in order from a power supply side to a load side, and a lightning arrester 3 is connected between the overcurrent detector section 43 and the zero phase current transformer 44.

Abstract: Malfunction of an earth leakage breaker due to a lightning surge is prevented, and when a lightning arrester is short-circuited and damaged by a high-level lightning surge, a power supply short circuit is prevented.

Abstract: A circuit breaker-includes: a casing having a base and a main cover secured to the base, the casing accommodating a circuit breaking mechanism; a recesses formed in one surface of the main cover, the opposite surface of which is on the side of the base, the recess being adapted to receive an auxiliary device of the circuit breaking mechanism; and an auxiliary cover mounted on the main cover in such a manner as to close the recess. The circuit breaker is automatically tripped when the auxiliary cover is opened, thus permitting installation of the auxiliary device thereon with high security.

Abstract: A composition of matter is provided which comprises low-shrinkage, wet-type unsaturated polyester (B.M.C.) having high thermal conductivity, glass fibers, and a particulate aluminum nitride filler having high thermal conductivity. Also provided is an electrical component housing which possesses high thermal conductivity and heat dissipation properties including a body of a low-shrinkage, wet-type unsaturated polyester (B.M.C.) composition having high thermal conductivity.

Abstract: A multipole circuit breaker of a type with a mechanism pole having a switching mechanism in which adjacent poles are disposed in opposition to the mechanism pole with an interphase wall therebetween and each having an internal attachment such as an alarm switch or the like but no switching mechanism. A latch engages a cradle of the switching mechanism and is arranged to be actuated by an automatic tripping device. A supporting shaft rotatably supports the latch, an a lever fixed on the supporting shaft engages the cradle. Actuators are fixed on the supporting shaft so as to engage the internal attachment of the respect adjacent poles. The supporting shaft is made of metal. Insulating caps are inserted and fixed onto end portions of the supporting shaft, the supporting shaft passing at portions of the insulating caps through the interphase walls. The actuators are inserted and fixed onto the insulating caps.

Abstract: A circuit interrupter which comprises a pair of separable contact structures each including a contact element, at least one of the contact structures being movable between a closed position and an open position relative to the other contact structure for opening and closing an electric circuit extending through the circuit interrupter, the movable contact structure having an arm support that is pivotable about an axis, a movable contact arm pivotally supported on the arm support and extending in a parallel and an opposite direction to the other contact structure for generating an electromagnetic repulsive force therebetween, and a biasing means connected between the arm support and the movable contact arm for biasing the movable contact arm to a predetermined position with respect to said arm support, and an operating mechanism connected to the arm support of the movable contact structure for separating the movable contact structure from the stationary contact structure in response to an overcurrent flowing t

Abstract: A circuit interrupter which comprises, in a compartment defined in an electrically insulating housing, a pair of separable contacts defining, when separated, an arcing region therebetween, and an operating mechanism, including a tripping unit and an operating handle, for opening and closing the separable contacts. The housing which includes an electrically insulating bottom wall has a gas exhaust passage having an inlet opening in the inner surface of the housing. The inlet of the gas exhaust passage is located in the bottom wall at a position effective for exhausting an arced gas generated in the arcing region without contacting the operating mechanism.

Abstract: A circuit breaker having a larger separation distance between a stationary contact 4 and a movable contact 6 in the automatic mode than in the manual mode. The pivot shaft 24 of a crank 13 is placed in a higher position than in a conventional circuit breaker, to thereby enable the arm 7 carrying the movable contact 6 to rotate through a greater angle. A stop plate 26 is provided to prevent the flex angle .theta. formed between a first link 11 and a second link 12 of a toggle mechanism 10 from becoming too small when the contacts are opened, which enables easy manual closure with the normal stroke of a switch handle 16 and avoids the need for a stronger spring 17.

Abstract: A circuit breaker having separable contacts and a releasable trip mechanism operable upon overcurrent conditions to automatically separate the contacts includes a moveable arm stop connected to the releasable mechanism for limiting travel of the moveable contact in the open circuit position. The moveable arm stop includes a cam portion having an extended surface to limit travel of the moveable contact and establish a first contact separation distance when the trip mechanism is latched, and a flat surface limiting travel of the moveable contact to establish a second, greater contact separation distance when the trip mechanism is released.