Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific quantity comparison means
Patent
1990-02-21
1991-10-15
Stephan, Steven L.
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific quantity comparison means
361 77, H02H 326
Patent
active
050579630
ABSTRACT:
An opposite phase detecting device for alternating current electrical equipments includes a zero cross circuit synchronizing positive half waves of first and second line voltages of a three-phase AC supply supplied to an AC electrical equipment and generating first and second synchronizing pulses each having a pulse width corresponding to an electrical angle of approximately 180 degrees, a counter circuit counting the first synchronizing pulses from the zero cross circuit, a one-shot multivibrator triggered by the second synchronizing pulse to thereby generate a reset pulse having a relatively short time interval, and an AND circuit generating a reset signal based on a logical multiplication of the reset pulse generated by the pulse generating circuit and the first synchronizing pulse generated by the synchronous circuit. The counter circuit is reset when supplied with the reset signal from the AND circuit. The counter circuit generates an opposite phase detection signal when the count value thereof reaches a predetermined value.
REFERENCES:
patent: 3838314 (1974-09-01), Boothman et al.
patent: 4045682 (1977-08-01), Poorbaugh et al.
patent: 4284939 (1981-08-01), Kawada et al.
patent: 4562507 (1985-12-01), Kudo et al.
patent: 4878208 (1989-10-01), Seki et al.
Kabushiki Kaisha Toshiba
Shaw, Jr. Philip M.
Stephan Steven L.
To Edward H.
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