BRIGHTNESS CONTROL OF CABLE RING OF AIRFIELD LIGHT SIGNAL SYSTEM Russian patent published in 2003 - IPC

FIELD: electrical engineering, automatic systems for stabilization and control of alternating voltage and current. SUBSTANCE: brightness control of cable ring of airfield signal system has power transformer which secondary winding has one tap as minimum, at least two units of keys built in parallel opposition, control unit incorporating phase-pulse converter which outputs are connected to controlling electrodes of keys, unit comparing measured value of current with reference one, squarer, integrator, storage with reference values of currents, unit determining numbers of keys and phases of their switching, current pickup which input is placed in network of secondary winding of power transformer and transmitter of phase of network voltage. One unit of keys is connected to tap of finish of secondary winding. Other unit of keys is connected to proper tap and all of them are interconnected. Input of squarer is connected to output of current pickup, output of squarer is connected to one of inputs of integrator, another input of integrator is connected to output of phase pickup and output of integrator is connected to one of inputs of comparing unit. Another input of comparing unit is connected to storage, output of comparing unit is connected to input of unit determining numbers of keys and phases of their switching which output is connected to one of inputs of phase-pulse converter. Another input of phase-pulse converter is connected to output of phase pickup. EFFECT: improved form of current nearing sinusoidal form thanks to exclusion of no-current condition by switching over of taps and upper tap of secondary winding of power transformer in the course of half-cycle. 3 cl, 3 dwg