Patent ID: 6095678
Filing Date: 2000-08-01
Classification: H01H

Abstract:
A method of calibrating a thermal trigger for an electrical switching device, the thermal trigger having a bimetal strip for each phase, one end of each bimetal strip being attached to the housing of the thermal trigger, the thermal trigger having two longitudinally displaceable positioned slides arranged in parallel, wherein the free end sections of the bimetal strips that are not attached to the housing and which bend outward under current loading in the direction of longitudinal displacement of the slides lie between both of the slides, the thermal trigger having a differential lever which is linked to one slide via a link joint and to the other slide via a tow connection, and which acts with at least one end section upon a trigger arrangement, and the thermal trigger having drive arms between each slide and each bimetal strip, the method comprising the steps of: attaching one end of the bimetal strips inside the housing of the trigger and putting the bimetal strips into a calibrating position by bending the bimetal strips outward, the bending being performed by applying a predetermined calibrating current for a predetermined heating-up time, then measuring the position of the free end sections of each bimetal strip on both folded ends opposite each other, then individually fitting both of the slides with hinged drive arms, then adjusting the drive arms on each slide using a calibration device provided with stops, including the step of sluing to the previously measured calibrating position of the individual bimetal strips, then attaching the drive arms on the slides in the pre-set calibrating position, and then mounting both of the slides provided with the drive arms to the differential lever inside the thermal trigger.