Control device for the actuation of switchgears according to a time

Abstract

The information on the state of switchgears (2.1;2.2) appearing on call circuits in the form of analog low-voltage signals is conveyed in parallel to a circuit block (4). The information is digitalized at given points in time in the form of binary values '0' or '1' and is transmitted in series to a microprocessor (1). Preferably the circuit block (4) comprises at least one shift register in cascade connection. Call circuits are coupled to the circuit block solely via a high-impedance resistor (3.1;3.2). The circuit block (4) is supplied by a voltage supply circuit (5) so that when one of the switchgears (2.1;2.2) is in the open state, a current flows alternately via one of the protection diodes (D1S.1,D2S.1;DIS.2,D2S.2) of the circuit block (4), and does not do so when one of the switchgears (2.1;2.2) is in the closed state. To ascertain whether a voltage (U.sub.1,U2) at the input (4.1;4.2) of the circuit block (4) is D.C. or A.C., the microprocessor (1) effects a multiple scanning within a time period of one to two network half-waves and makes an analysis of values detected consecutively in time. The control device is especially well suited for the control of art oil or gas burner in continuous operation.