Tap changing power regulator for airport lighting

Claim 1

A power current regulator circuit of the type comprising: an input for an alternating mains feed; a first transformer whose primary winding is connected to said input and whose secondary winding contains a staged set of taps; at least one intermediate transformer similar to the first transformer; a last transformer whose secondary winding is intended to be connected to the load to be regulated via a member for measuring the load current or the load voltage; a series of controlled switches suitable for connecting each tap of each transformer to the following transformer; and control means for switching one of said switches in each of said series to the conducting state; wherein said control means comprise: a comparator stage for comparing the value measured by said measuring member with a reference value; a clock signal generator triggered by the beginning of each zero crossing in the mains voltage, and subsequently by the zero crossing in the current flowing through the load; an up/down counter circuit suitable for defining a count capable of changing stepwise depending on the result of the comparison and at the rate of the clock signal, and including as many up/down counters as there are tapped transformers; latch memories connected to the parallel outputs from the up/down counters; means capable of actuating the latch memories with at least one predetermined delay relative to the clock signal depending on the direction of counter variation; a timing circuit for a selected timing period, and triggered at another predetermined delay relative to the clock signal; and decoder means connected to the parallel outputs of the latch memories in order to actuate said series of switches during said timing period.