GB1293037A - Arrangements for monitoring a plurality of flame locations simultaneously - Google Patents

Abstract

1293037 Flame monitor LANDIS & GYR AG 26 Aug 1970 [3 Sept 1969] 41042/70 Heading F4T In a flame monitoring arrangement for monitoring a plurality of flame locations simultaneously, an alternating voltage from a tapping 24 and an end 27 of a transformer secondary winding is applied to pairs of electrodes 15 and 18, 16 and 19 &c. by way of capacitors 28 and resistors 29, 30 &c., the electrodes allowing no current flow unless a flame is present, in which case partial rectification occurs allowing capacitors 28 to charge up until a unijunction transistor 32 becomes conducting. This allows capacitor 28 to discharge through resistor 34 so charging a capacitor 38 to a voltage which causes transistor 37 to conduct, the output signals from the respective transistors 37 being combined by a circuit containing diodes 45, 46, 48 and 49 and a transistor 57. This circuit acts as an OR- circuit or an AND-circuit according to whether a selector switch 54 is connected to contact 52 or 53 respectively. The position of selector switch 54 is determined by a relay 59 energized by a gas burner automatic control arrangement 1 (not shown). The output of the AND and OR circuits is determined by whether transistor 57 conducts or not, the conducting state allowing a relay 58 to be energized to operate a switch 62 to give an output signal. When the burners are all supposed to be operating an output fault signal is produced if one or more of the flames fails; whereas when the burners are all supposed to be out of operation a fault signal is produced if one or more of the flames is still alight.