Method and apparatus for separating and analyzing composite AC/DC waveforms
AssigneeADB-Alnaco, Inc.
InventorHarold Richard Williams
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Abstract
The present invention includes a method for separating AC and DC components of a composite waveform, and an inductive device capable of performing the method. The present invention also includes a ground fault condition monitoring system containing an inductive device of the present invention, and an electrical distribution system containing such a ground fault condition monitoring system, such as one for a lighting system.
Claims10
A method for substantially separating the DC component from the AC component of a composite AC/DC waveform in an airfield lighting or control system, said method comprising the steps of:
- a. obtaining an electrical connection to a composite AC/DC waveform;
- b. conducting said AC/DC waveform through an inductive device comprising:
- i. an inductor coil having an input pole, an output pole and a capacitor connected to said output pole so as to load said inductor coil;
- ii. a driver winding for said inductor coil, said driver winding adapted to sense AC current flow through said inductor coil;
- iii. a sampling element connected to said driver winding and adapted to detect said AC current in the form of a voltage across said sampling element;
- iv. signal processing circuitry comprising:
- (1) an inverting amplifier adapted to amplify said voltage;
- and
- (2) a phase shifter adapted to shift the phase of said voltage;
- v. a power amplifier coupled to said signal processing circuitry and also coupled to the other of said driver winding;
- and
- c. measuring the DC component of said AC/DC composite waveform through said output pole of said inductor coil.
A method for detecting a ground fault condition in an active AC circuit of an airfield lighting or control system, said method comprising the steps of:
- a. obtaining a circuit having an active AC waveform therein;
- b. superimposing upon said AC waveform a DC voltage, said DC voltage produced by a DC voltage source, whereby a composite AC/DC waveform is produced;
- c. separating said DC voltage from said composite AC/DC waveform;
- and
- d. directly measuring current flowing through said DC voltage source whereby the existence of a ground fault condition in said circuit is determined directly.
A method for detecting a ground fault condition in an active AC circuit, said method comprising the steps of:
- a. obtaining a circuit having an active AC waveform therein;
- b. superimposing upon said AC waveform a DC voltage, said DC voltage produced by a DC voltage source, whereby a composite AC/DC waveform is produced;
- c. separating said DC voltage from said composite AC/DC waveform using an inductive device comprising:
- i. an inductor coil having an input pole and an output pole, said inductive coil having a capacitor connected to said output pole so as to load said inductive coil;
- ii. a driver winding for said inductor coil, said driver winding adapted to sense AC current flow through said inductor coil;
- iii. a sampling element connected to said driver winding and adapted to detect said AC current;
- and
- iv. signal processing circuitry adapted to measure the DC component of said AC/DC composite waveform through said output pole of said inductor coil
- d. measuring current flowing through said DC voltage source whereby the existence of a ground fault condition in said circuit may be determined.
A method for substantially separating the DC component from the AC component of a composite AC/DC waveform, said method comprising the steps of:
- a. obtaining an electrical connection to a composite AC/DC waveform;
- b. conducting said AC/DC waveform through an inductive device comprising:
- i. an inductor coil means having an input pole, an output pole, and a capacitor connected to said output pole for loading said inductor coil, wherein said inductor coil comprises a driver winding means for sensing AC current flow through said inductor coil means;
- ii. a sampling element for connecting to said driver winding means and for detecting said AC current in the form of a voltage across said sampling element;
- iii. signal processing means comprising an inverting amplifier means for amplifying said voltage and a phase shifter means for shifting the phase of said voltage;
- iv. a power amplifier means coupled to said signal processing means and also coupled to the other of said driver winding means;
- and
- c. measuring the DC component of said AC/DC composite waveform through said output pole of said inductor coil means.
A method for detecting a ground fault condition in an active AC circuit, said method comprising the steps of:
- a. obtaining a circuit having an active AC waveform therein;
- b. superimposing upon said AC waveform a DC voltage, said DC voltage produced by a DC voltage source, whereby a composite AC/DC waveform is produced;
- c. separating said DC voltage from said composite AC/DC waveform using an inductive device comprising:
- i. an inductor coil means having an input pole, an output pole, and a capacitor connected to said output pole for loading said inductor coil means;
- ii. said inductor coil means comprising a driver winding means for sensing AC current flow through said inductor coil means;
- iii. a sampling element means connected to said driver winding means for detecting said AC current in the form of a voltage across said sampling element;
- and
- iv. signal processing means for measuring the DC component of said AC/DC composite waveform through said output pole of said inductor coil means
- d. Measuring current flowing through said DC voltage source whereby the existence of a ground fault condition in said circuit may be determined.
Dependencies are inferred from the claim text.