GB879994A - Improvements in flame failure or heat source detectors - Google Patents

Abstract

879,994. Burner control by radiation-sensitive devices. ASQUITH ELECTRICS (COLNE) Ltd. April 6, 1960 [April 17, 1959], No. 13090/59. Class 40(3) [Also in Group XI] In a circuit, for detecting the failure of a flame or of a source of heat, comprising a resistance element energized by direct current through a transformer and rectifier from an A.C. source in series with a relay coil, the current through which varies with the temperature of the resistance element to detect the presence or absence of heat, a contact member operated by the relay coil directly controls a valve to shut off the fuel supply in the event of flame failure at a burner or to control directly the operation of a switch for a fuel pump or electricity supply. As supplied to a spark ignition system in which gas supplied to a burner BU through a valve V is ignited by a plug P, the resistance element E heated by the flame F is in series with the operating coils of relays Rl, R2 fed with D.C. voltage from a rectifier D and transformer T<SP>1</SP> energized from mains A.C. when a switch S is closed. The relay R2 energized when switch S is operated, closes contact r3 and the ignition system is brought into operation by the actuation of a push-button B<SP>1</SP> after the switch S has been closed. At contacts b2 the transformer T2 is energized so that its winding t is operative to ignite the sparking plug P, and over contacts bl a relay coil V1 is operated to open the valve V to allow gas to pass to the burner BU which becomes operative. The flame F increases the resistance of the element E with the result that relay R1 releases closing contacts r1, r2 so that an indicating lamp L is illuminated. The button B<SP>1</SP> is now released, and the coil V1 is energized to hold the valve V open over closed contact rl. If the gas supply, heat source, or ignition fails, relay R1 is energized under control of the element E, and at contact rl the coil V1 is de-energized so that the valve V closes. At contact r2 the lamp L is extinguished. If the element E should fail, relay R2 is de-energized so that at contact r3 the circuits of the lamp L and of relay V1 are broken.