Abstract: A method and system for visually guiding an aircraft in its landing approach to a runway having an approach area equipped with approach lights operable in off, low, medium, and high intensity states. The lights are communicated with a secondary side of a transformer, which has a primary side with low, medium, and high taps that correspond to the light states. Off, low, medium, and high lighting intensity requests correspond to the low, medium, and high states of the plurality of lights. AC power is switched between the transformer taps in response to a request for an increase in lighting intensity. Power is sequentially applied to the taps by supplying the power to the low tap for a first predetermined time interval before supplying the power to the medium tap.

Abstract: A method and system for visually guiding an aircraft in its landing approach to a runway having an approach area equipped with approach lights operable in off, low, medium, and high intensity states. The lights are communicated with a secondary side of a transformer, which has a primary side with low, medium, and high taps that correspond to the light states. Off, low, medium, and high lighting intensity requests correspond to the low, medium, and high states of the plurality of lights. AC power is switched between the transformer taps in response to a request for an increase in lighting intensity. Power is sequentially applied to the taps by supplying the power to the low tap for a first predetermined time interval before supplying the power to the medium tap.

Abstract: A UPS having a ferroresonant transformer is selectively switched from AC line voltage to an inverter by a control method and apparatus using fuzzy logic to select an optimum switching point. The control apparatus and method senses output load current, output voltage and input voltage. Output current is used to calculate output load as a percentage of full load. First membership functions relating to percent load, second membership functions relating to output voltage, third membership functions relating to input voltage switching points, and rules using percent load membership and output voltage membership as antecedents and values of input voltage switching points as consquents as determined by regulation characteristics of the ferroresonant transformer, are used to execute a fuzzy inference and generate dynamic input voltage switching points for comparison with line input voltage to control switching of the UPS between line and inverter sources.