AFCI which detects and interrupts line side arcing
AssigneePass & Seymour, Inc.
InventorsBruce F. Macbeth, Jeffrey C. Richards
Life of this patent
Estimating the term…
Abstract
An arc fault causes the line voltage across the line terminals of an arc fault circuit interrupter (AFCI) to change its characteristic voltage pulse shape as the line voltage is momentarily removed from the AFCI terminals after the arc extinguishes and before it re-strikes by introducing a flat voltage portion to the pulse shape. This flat voltage portion changes the voltage pulse width. An arc detector/processor detects this change in pulse width to produce a signal indicative of upstream (line side) arcing. The flat voltage portion can also be detected using clamping diodes and charging capacitors.
Claims50
An arc fault detector operatively connected to first and second lines of an AC electric power distribution system, comprising:
- first means for determining a first width of a voltage pulse of a line voltage across said first and second lines in an absence of an arc fault on a line side of said arc fault detector;
- second means for determining a second width of a voltage pulse of said line voltage across said first and second lines in a presence of said arc fault on said line side of said arc fault detector;
- comparison means for comparing said first width to said second width;
- and
- means for producing a signal when said first width exceeds said second width for a predetermined number of line cycles of said line voltage.
An arc fault detector operatively connected to first and second lines of an AC electric power distribution system, comprising:
- means for sampling a waveform of a line voltage across said first and second lines on a line side of said arc fault detector;
- and
- means for determining when said waveform changes from a normal sine wave to an abnormal sine wave characterized by a flat voltage region, thereby indicating an arc fault.
An arc fault detector operatively connected to first and second lines of an AC electric power distribution system, comprising:
- means for determining a width of a voltage pulse of a line voltage across said first and second lines in a presence of an arc fault on a line side of said arc fault detector;
- comparison means for comparing said width to a width constant held in a memory;
- and
- means for producing a signal when said width exceeds said width constant.
An arc fault detector operatively connected to first and second lines of an AC electric power distribution system, comprising:
- first means for detecting a shift from a sine waveform to a flat top waveform which has a voltage level between two predetermined levels for a predetermined interval during a half wave;
- second means for detecting said shift for a predetermined number of half waves;
- and
- means, responsive to said first and second means, for producing a signal.
An arc fault detector operatively connected to first and second lines of an AC electric power distribution system, comprising:
- means for producing a first signal proportional to the AC power line voltage;
- means for producing a second signal phase shifted from said AC power line voltage;
- comparison means for comparing said first and second signals;
- and
- means for producing a detection signal when a magnitude of said first and second signals are simultaneously LOW.
An arc fault detector operatively connected to first and second lines of an AC electric power distribution system, comprising:
- first means for detecting a shift from a sine waveform to a flat top waveform after a beginning of a half cycle of AC electric power, wherein said flat top waveform has a voltage level between two predetermined voltage levels for a predetermined interval during said half cycle;
- second means for detecting said shift over a predetermined number of half cycles;
- and
- means, responsive to said first and second means, for producing a signal.
Dependencies are inferred from the claim text.