Method of calibrating a thermal trigger for an electrical switching device

摘要

A method of calibrating a thermal trigger for an electrical switching device starts with fastening bimetal strips (1) for each phase in the housing of the trigger. Thereafter, the bimetal strips (1) are heated-up with a predetermined calibration current for a predetermined time, and are thus brought into a calibrated position. In the calibrated position, the positioning of each of the free end sections of each bimetal strip (1) is measured on both folded ends opposite each other. Then, two slides (3, 4) are fitted with two hinged drive arms (5,6) and are retained in a calibration device. Stops (9) bring the drive arms (5, 6) into the previously measured calibrated position of the assigned bimetal strip (1) by sluing. In the calibrated position, the other single- piece arms (8) with the trigger arms (5,6) are attached to the slide (3,4) . The slides (3,4) that are provided with rigid drive arms (5, 6) in calibrated positions are assembled in the trigger together with a differential lever (12) actuating one of the two slides (3,4). This method is especially suited for a fully automatic assembly line.