Thermally controlled electromagnetic relay - has bimetal strip armature whose deformation increases contact engagement pressure and delays opening after de-energising

摘要

The relay comprises a laminated bimetal strip and resilient leaf bridge pivoted at one end to one terminal and carrying a contact cooperating with a fixed contact of a second terminal. The bridge carries a rounded lug and is spring biassed towards an open position. A member is axially movable against a spring by an electromagnet to close the contact by engaging a notch in the member underside with the lug. Current through the bimetal strip deforms the bridge to force the lug against the notch thus preventing withdrawal of the member when the electromagnet is energised until the bimetal strip has cooled down.