Miniature circuit breaker

A miniature circuit breaker comprising an insulative housing, first and second electrical terminals supported by said housing, manually operable actuating means pivotally supported by said housing, fixed and movable electrical contacts in said housing, an electrically conductive fixed contact support structure supporting said fixed contact, with the fixed contact support structure being electrically connected to the first terminal, an elongated, electrically conductive, movable contact arm supporting said movable contact, and being movable between closed and open positions in which the fixed and movable electrical contacts are respectively engaged and separated, a trip mechanism which includes a bi-metal having a first end electrically connected to the movable contact arm and a second end electrically connected to said second terminal, and an operating mechanism comprising an operating member pivotally fixed to the housing, and a tension spring having first and second ends and a longitudinal axis therebetween, with said operating member having first and second ends and a longitudinal axis therebetween, with the first end being releasably engageable with said trip mechanism, the improvement comprising:

• said movable contact arm having first and second ends, a contact support side, and an opposite spring supporting side, with the first end of said movable contact arm being actuatable by the manually operable actuating means and with the movable contact being fixed to the contact supporting side adjacent to the second end of said movable contact arm,
• the second end of said pivotable operating member being adjacent to and spaced from the spring supporting side of said movable contact arm, in both the engaged and separated positions of the fixed and movable contacts,
• the first and second ends of said tension spring respectively linking the second end of said pivotable operating member and the spring supporting side of said movable contact arm, with said longitudinal axes of the tension spring and movable contact arm being in spaced, substantially parallel relation in both the engaged and separated positions of the fixed and movable electrical contacts,
• and wherein the fixed contact support structure includes a contact supporting leg portion which is in closely spaced relation with the movable contact arm, when the fixed and movable contacts are in engagement, to provide a reverse current loop which magnetically aids in rapidly separating the fixed and movable contacts upon the onset of an over current condition.