CIRCUIT BREAKER WITH LOW CURRENT MAGNETIC TRIP

A circuit breaker having a trip mechanism comprising a primary armature which is attracted toward a bimetal by magnetic flux produced by a predetermined overcurrent flowing through the bimetal to unlatch an operating mechanism and open electrical contacts, includes a pivoted supplemental armature which is also attracted toward the bimetal by the overcurrent and which bears against and urges the primary armature toward the bimetal to thereby reduce the predetermined overcurrent at which the breaker opens the electrical contacts. The supplemental armature comprises a flat strip of magnetically permeable material which is bent at one end to form a hook which merely drops into a recess in the breaker housing. Integral flanges on the strip form a magnetic yoke which concentrates the magnetic flux to increase the sensitivity of the magnetic trip function.