Adjustable circuit breaker thermal trip unit
AssigneeWestinghouse Electric Corp.
InventorsJohn K. Livesey, James N. Altenhof, Jr.
Life of this patent
Estimating the term…
Abstract
Apparatus for adjusting the calibration of a thermal trip unit which is to be used in conjunction with an electrical circuit breaker. A rotatable knob is provided which adjusts the trip unit to between one hundred percent of the rating of the circuit breaker and some value which is less than one hundred percent. An adjustable stop screw is provided to engage the rotatable knob when the knob is rotated to adjust the calibration of the trip unit to the desired value which is less than one hundred percent of the rating of the breaker. The adjustable stop screw thereby limits travel of the adjustable knob between only one hundred percent of the rating of the circuit breaker and the desired value which is less than one hundred percent.
Claims18
A circuit breaker, comprising:
- separable main contacts for opening to interrupt electrical current flowing through an interconnected load;
- rotatable trip bar means rotatable about an axis and translatable along said axis, said trip bar means having a face portion capable of being abutted by another member for the purpose of causing rotation of said trip bar means;
- operating means interconnected mechanically between said separable main contacts and said rotatable trip bar means for causing said separable main contacts to open in relationship to the rotation of said rotatable trip bar means;
- trip means angularly movable relative to said face portion along a predetermined path of travel as a function of said electrical current to abut said face portion at a predetermined location along said path of travel to cause said trip bar means to rotate to cause said separable main contacts to open at a predetermined magnitude of said electrical current;
- and
- adjustment means cooperable with said trip bar means for adjustment of the translational disposition of said trip bar means relative to said trip means within a range of adjustment to cause said face portion to be abutted by said trip means at a different location along said path of travel of said trip means to cause said trip bar means to rotate to cause said separable main contacts to open at a different magnitude of said electrical current.
A trip unit usable with a circuit breaker of the kind which has separable main contacts for opening to interrupt electrical current flowing through an interconnected load, and operating means interconnected mechanically to said separable main contacts for causing said separable main contacts to open comprising:
- rotatable trip bar means rotatable about an axis and translatable along said axis, said trip bar means having a face portion capable of being abutted by another member for the purpose of causing rotation of said trip bar means;
- trip means angularly movable relative to said face portion along a predetermined path of travel as a function of said electrical current to abut said face portion at a predetermined location along said path of travel to cause said trip bar means to rotate to activate said operating means to cause said separable main contacts to open at a predetermined magnitude of said electrical current;
- and
- adjustment means cooperable with said trip bar means for adjustment of the translational disposition of said trip bar means relative to said trip means within a range of adjustment to cause said face portion to be abutted by said trip means at a different location along said path of travel of said trip means to cause said trip bar means to rotate to cause said separable main contacts to open at a different magnitude of said electrical current.
Dependencies are inferred from the claim text.