Electromechanical relays
AssigneeJ. H. Fenner & Co. Limited
InventorsAshley D. Derrick, Nicholas Hobson
Life of this patent
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Abstract
A device for preventing welding of the switch contacts of a heavy duty electromechanical relay comprises means (15, 16 and 17) adapted in use for monitoring the voltage supply to the relay coil (2) and detecting low voltage excursions therein. A counter (14) counts the number of low voltage excursions in the voltage supply to the relay coil (2) and an electronic switch (12) disconnects the voltage supply to the relay (2) if the number of low voltage excursions counted exceeds a predetermined number.
Claims6
A device for preventing welding of the switch contacts of a relay caused by oscillation of the switch contacts due to low voltage excursions in the voltage across the relay coil, comprising a counter having a clock input which is clocked each time the switch contacts open and close following the connection of a voltage supply to the relay coil, and switching means for disconnecting the voltage supply to the relay when the clock count exceeds a predetermined number.
Dependencies are inferred from the claim text.