GB1459055A - Electrical control circuitry - Google Patents

Abstract

1459055 Burner control ELECTRONICS CORP OF AMERICA 23 Dec 1974 [11 Jan 1974] 55483/74 Heading F4T A burner control apparatus comprises a flame sensor 66 to produce a signal when a flame is present, lockout apparatus 42, 42-1, 42-2, for de-energizing the apparatus, a device 108, 108-1 for actuating fuel control means, a preignition timing interval circuit 144 and an ignition timing interval circuit 160 having a common capacitor 146 one of the timing intervals being a function of the charging of the capacitor and the other being a function of the discharging of the capacitor means 24 responsive to a request for burner operation to initiate an ignition sequence by actuating the timing circuit circuitry responsive to the actuated timing- circuit for energizing the control device at the end of the first timing interval, flame signal responsive circuitry 22 responsive to a signal from the flame sensor 66 to maintain the control device energized and means responsive to the end of the ignition timing interval to deenergize the control device and cause lockout apparatus 42, 42-1, 42-2, to lockout the burner control apparatus in the absence of the signal from the flame sensor. In operation, power is supplied through terminals 10, 12 to transformer 16 and thence to flame sensor 66. Call for burner switch 24 closes and the air flow from blower motor 28 is sensed to thus energize transformer 40 and a D.C. voltage appears at terminal 52 of full-wave rectifier 46. Capacitor 146 is uncharged and in the absence of a signal from circuit 22 transistors 98, 112 and 120 are non-conducting. Lockout switch actuator 42 is heated, pre-ignition delay capacitor 146 is charged to thus initiate charging of trial-forignition capacitor 162, and after a delay due to timing network 144, the ignition and pilot fuel are turned on 30, 32. A flame signal from circuitry 22 causes the ignition 32 to be turned-off and initiates main-fuel flow 34. If the flame signal is lost, contacts 110-2 are opened and the fuel supply is turned-off and contacts 108-1 are opened to prevent ignition or pilot-fuel flow. In a modification, the control circuitry between terminals 52, 54, Fig. 2 (not shown), is altered. In a further modification, terminals 300-, 302 are connected to a D.C. supply, which is energized in response to a call for burner, the onset of the ignition sequence being delayed by a switch 304.