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US 5,289,110 AGranted
Input current responsive, tap changing transformer system
AssigneeCooper Industries, Inc.
InventorJohn A. Slevinsky
Life of this patent
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Abstract
A system for providing a constant current to airport or airfield signs is disclosed. The system receives input currents of varying amperages which also supply, and allow dimming of, runway or taxiway lights. According to various exemplary embodiments of the present invention, a high power factor is achieved which provides greater cost efficient operation of the signs.
Claims11
A system for providing a constant output current to lamps in signs and which receives an input current which can vary in amperage comprising:
- an input line for receiving said input current, wherein said input current has one of a plurality of amperages;
- a current monitoring transformer which monitors said input current and which generates a voltage which is proportional to said input current;
- a reference voltage generator for generating a reference voltage;
- a plurality of voltage dividers for transforming said voltage into a plurality of different voltages;
- a plurality of comparators, each of which receives one of said plurality of different voltages at a first input, said reference voltage at a second input and outputs a high level logic signal if said first input is greater in magnitude than said second input;
- and
- a tapped transformer having a plurality of taps, wherein one of said plurality of taps is selected in response to said high level logic signal, for outputting said constant output current to said lamps.
4 more elements
A system comprising:
- means for receiving an input alternating current having one of a plurality of amperages;
- means, responsive to said means for receiving, for detecting said one amperage and generating a plurality of different voltage levels proportional to of said one amperage;
- means for generating a reference voltage;
- means for comparing said voltage levels and said reference voltage;
- means for selecting a tap of a transformer having a plurality of taps based on a result of said means for comparing;
- and
- means for outputting an output current, in response to said selected tap, which has a substantially constant amperage even if said one amperage of said input alternating current changes to another of said plurality of amperages.
4 more elements
Dependencies are inferred from the claim text.