SCHALTUNGSANORDNUNG ZUR STABILEN REALISIERUNG GROSSER PHASENANSCHNITTWINKEL

摘要

The inductive load (18) is connected to the AC network on the one hand directly and on the other hand via a triac (24). A series circuit which comprises a resistor (4), a varistor (6) and a further resistor (5) is connected in parallel with the triac (24) and is supplied via a first diode (2). The anode of the first diode is connected to one connection of the load, and the cathode of the first diode is connected to one end of the series circuit. A capacitor (7) is charged by the positive half-cycle of the network voltage via the resistor (4) and another diode (11) to a voltage which is limited by the first-mentioned varistor (6). The discharging of the capacitor starts via a further diode (10) when the voltage falls below the aforementioned limited voltage. In this case, a negative pulse is emitted to the control electrode of the triac, via a further varistor (25), in order to trigger the triac (24). In this way, triggering pulses are emitted to the triac in the last part of each positive half-cycle such that the power supplied to the load is only very slightly dependent on the operating voltage and ageing of the components. <IMAGE>