Circuit breaker with low current magnetic trip

Abstract From the Canadian patent

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 …