Patent ID: 6218917
Filing Date: 2001-04-17
Classification: H01H

Abstract:
A thermal trip unit for electric circuit breakers comprising:a strap arranged for connection with an electric circuit;a trip bar assembly rotatably mounted about a pivot above said strap;a bimetal element having a first end and a second end, said bimetal element electrically connected with said strap at said first end and arranged for striking said trip bar assembly at said second end;a calibration device having a first end and a second end, said calibration device extending through said trip bar assembly, the second end of said calibration device for contacting said second end of said bimetal element;a heater element electrically connecting with said bimetal element and said strap at one end and a circuit breaker contact carrier at an opposite end, said second end of said bimetal element movable towards said second end of said calibration device upon current transfer through said heater element; and,a drive connected to the first end of said calibration device for automatically moving said calibration device into contact with said second end of said bimetal element when said current transfer through said heater element exceeds a predetermined value.