US 4,080,582 A · Circuit breaker with improved trip mechanism

Abstract

A single-pole circuit breaker or a plural-pole circuit breaker of the type having a common trip bar extending between poles whereby any pole tripping acts therethrough to trip the other pole or poles. The breaker is provided with an improved trip mechanism comprising a subassembly for each pole wherein all of the thermal and magnetic trip elements are mounted on a breaker terminal plate that acts as a base therefor and which is secured to the breaker housing. This trip mechanism also comprises shunt contacts mounted on the armature and bimetal for closing a protective shunt across the bimetal on magnetic trip and for rocking action on shunt contacts due to bimetal movement to break any welds therebetween; a field test mechanism having a spring-biased rotary trip member accessible from the outside and an eccentric lever attached thereto for manually tripping the breaker for test purposes; and an insulator lining the lower surface of the contact finger to prevent the arc from re-striking below the contact when the contacts trip open thereby to enhance completion of the tripping action.

Claims15

Dependent claims

In an electrical circuit breaker, the combination comprising:

an insulating housing having a compartment therein enclosing a circuit breaker mechanism comprising:
a pair of terminals extending from said compartment to the exterior for connecting said circuit breaker to an external circuit;
a stationary contact connected to one of said terminals within said compartment;
a movable member having a contact thereon within said compartment operable for engaging or disengaging said stationary contact;
means comprising an operating handle and toggle linkage and latching mechanism for operating said movable member;
tripping means for controlling said latching mechanism to release said toggle linkage and trip said movable member and its contact open;
and a thermal and magnetic trip subassembly for actuating said tripping means in response to overload conditions, said subassembly comprising magnet and bimetal members rigidly mounted on the other terminal with said bimetal member electrically connected thereto, an armature member resiliently mounted on and electrically connected to said other terminal for attraction by said magnet, and means electrically connecting said bimetal member to said movable member so as to form a current path from said one terminal to said other terminal through said stationary and movable contacts.

4 more elements

In a plural-pole electrical circuit breaker having an insulating housing including a compartment therein for the circuit breaker mechanism, which mechanism comprises in each pole thereof a pair of terminal plates, one of said plates extending from each end of each said compartment for connection to an external circuit, a stationary contact mounted to one plate of each said pair thereof, and a movable contact finger subassembly having a rotatable shaft extending between compartments and a contact finger having a contact at one end thereof rigidly mounted on said shaft at its other end in each said compartment for limited rotation therewith to close and open said contacts, a manual lever operated overcenter toggle spring and linkage mechanism in one pole thereof including a latch therefor and a common trip mechanism for controlling said latch for setting said movable contact finger in closed position from which it may be tripped open by overload current, the improvement comprising:

a thermal and magnetic trip subassembly in each said compartment for actuating said common trip mechanism comprising:
elongated magnet and bimetal members mounted on and electrically connected to said other terminal plate in parallel so that said bimetal member extends between the poles of said magnet member which has a U-shaped configuration to magnetize the same when current flows in said bimetal member;
an elongated armature member and flexible means mounting the same on and electrically connecting the same to said other terminal plate;
shunt contacts and means mounting the same in electrical connection on said armature and bimetal members respectively for shunting large currents from said bimetal member on magnetic trip;
means for mounting said second terminal plate to said housing whereby to mount said thermal and magnetic trip subassembly in said compartment;
and a flexible conductor connecting said movable contact finger to the shunt contact mounting means of said bimetal member in the respective compartment thereby to allow current flowing through the breaker contacts to flow through said bimetal member when said shunt contacts are open or in shunt thereof through said shunt contacts and said armature member to said other terminal plate when said shunt contacts are closed.

3 more elements

Dependencies are inferred from the claim text.

Circuit breaker with improved trip mechanism

Life of this patent

Circuit breaker with improved trip mechanism

Life of this patent

Abstract

Claims15