Claims
- 1. A thermal-magnetic trip unit for molded case circuit breakers comprising:
- a thermally-responsive electrically conductive element arranged for connection with a circuit breaker line or load strap;
- a magnetically responsive element within a circuit breaker enclosure having top and bottom parts, said bottom part at least partially surrounding said electrically conductive element providing a magnet force in proportion to circuit current through said electrically conductive element;
- a latching armature positioned a predetermined separation distance from said magnetically responsive element to define a magnetic separation gap, said latching armature having top and bottom parts, said bottom part arranged for retaining a circuit breaker releasable element under quiescent current through said electrically conductive element and releasing a circuit breaker releasable element under overload current through said electrically conductive element, said top part of said latching armature interfacing with said top part of said magnetically responsive element through a predetermined point of contact; and
- a compression spring holding said top part of said latching armature against said top part of said magnetically responsive element, said spring defining a line of force acting on said latching armature and said magnetically responsive element above said predetermined point of contact, said predetermined point of contact comprising a protrusion on said top part of said magnetically responsive element.
- 2. A thermal-magnetic trip unit for molded case circuit breakers comprising:
- a thermally-responsive electrically conductive element arranged for connection with a circuit breaker line or load straps;
- a magnetically responsive element within a circuit breaker enclosure having top and bottom parts, said bottom part at least partially surrounding said electrically conductive element providing a magnet force in proportion to circuit current through said electrically conductive element;
- a latching armature positioned a predetermined separation distance from said magnetically responsive element to define a magnetic separation gap, said latching armature having top and bottom parts, said bottom part arranged for retaining a circuit breaker releasable element under quiescent current through said electrically conductive element and releasing a circuit breaker releasable element under overload current through said electrically conductive element, said top part of said latching armature interfacing with said top part of said magnetically responsive element through a predetermined point of contact; and
- a compression spring holding said top part of said latching armature against said top part of said magnetically responsive element, said spring defining a line of force acting on said latching armature and said magnetically responsive element above said predetermined point of contact, said predetermined point of contact comprising a protrusion on said top part of said latching armature.
Parent Case Info
This is a division of application Ser. No. 07/841,182, filed Feb. 25, 1992.
US Referenced Citations (4)
Divisions (1)
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Number |
Date |
Country |
Parent |
841182 |
Feb 1992 |
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