Patent ID: 6980069
Filing Date: 2005-12-27
Classification: H01H

Abstract:
1. A magnetic trip unit for actuating a latching mechanism to trip a circuit breaker upon an overcurrent condition, the magnetic trip unit including: a first electrically conductive strap configured to conduct an electrical current; a first magnet yoke disposed proximate to said first electrically conductive strap, said first magnet yoke comprising inwardly extended flanges defining a gap “z” therebetween; and a first armature pivotally disposed proximate to and adjustable to define a first and a second distance “L” from said inwardly extended flanges of said first magnetic yoke; said first armature being in operable communication with the latching mechanism; said first armature and said first magnet yoke providing a magnetic path therebetween; said magnetic path therebetween consisting of spaced apart facing surfaces of each of said first armature and said first magnet yoke; said magnetic path therebetween having a reluctance to magnetic flux; said reluctance is adjusted to prevent saturation of said magnetic flux when said current through said strap is a first number (X) times a rated current of the circuit breaker and said reluctance is adjusted to promote saturation of said magnetic flux when said current through said strap is a second number (Y) times said rated current of the circuit breaker; wherein said first number is a number smaller than said second number; wherein in response to a first current through said strap being about 3 times a rated current of the circuit breaker, and said first distance “L” being less than said gap “z”, a first magnetic torque is developed at said first armature; wherein in response to said first current through said strap, and said second distance “L” being greater than said gap “z”, a second magnetic torque is developed at said first armature; and wherein said first magnetic torque is equal to or greater than about 3 times said second magnetic torque.