Magnetic device for a magnetic trip unit

A circuit breaker including:

• a first contact arm arranged between first and second electrically conductive straps;
• a latching mechanism configured to move said first contact arm out of contact with said first and second electrically conductive straps;
• a first magnet yoke disposed proximate to said first electrically conductive strap, said first magnet yoke comprising inwardly extended flanges that define 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.

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 magnet yoke configured to conduct an electrical current, said first magnetic yoke configured as a U-shaped bight defined by flanges extending toward each other having a gap “z” therebetween;
• and
• a first armature pivotally disposed proximate to said first magnetic yoke in operable communication with the latching mechanism, said first armature and said first magnet yoke adjustable for providing a magnetic path therebetween having a first distance “L” and a second distance “L” separating said first armature and said magnet yoke, 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;
• 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.

A magnetic trip unit for actuating a latching mechanism to trip a circuit breaker upon an overcurrent condition, the magnetic trip unit comprising:

• an electrically conductive strap configured to conduct an electrical current;
• a magnet yoke disposed proximate to said electrically conductive strap, said magnet yoke comprising inwardly extended flanges that define a gap “z” therebetween and that partially surround said electrically conductive strap;
• and
• an armature pivotally disposed proximate to and adjustable to define a first and a second distance “L” from said inwardly extended flanges of said magnetic yoke;
• said armature being in operable communication with the latching mechanism;
• 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 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 armature;
• wherein said first magnetic torque is equal to or greater than about 3 times said second magnetic torque;
• wherein in response to a second current through said strap being about 7.5 times the rated current of the circuit breaker, and said first distance “L” being less than said gap “z”, a third magnetic torque is developed at said armature;
• wherein in response to said second current through said strap, and said second distance “L” being greater than said gap “z”, a fourth magnetic torque is developed at said armature;
• and
• wherein said third magnetic torque is equal to or greater than about 6 times said fourth magnetic torque.