OVER AND UNDER EXCITATION PROTECTION CIRCUIT FOR ALTERNATING CURRENT POWER SYSTEMS INCLUDING IMPROVED DEMODULATOR CIRCUIT
First Claim
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1. A demodulator circuit comprising:
- a first pair of terminals for receiving an alternating voltage;
a first circuit branch connected between one of said pair of terminals and a common circuit point and comprising a first pair of diodes connected in series by like polarity electrodes thereof;
a second circuit branch connected between the other of said pair of terminals and said common circuit point and comprising a second pair of diodes connected in series by like polarity electrodes thereof, said electrodes being of opposite polarity to the interconnected electrodes of said first pair of diodes;
a Zener diode connected from the midpoint between said first pair of diodes and the midpoint between said second pair of diodes;
a transformer winding connected across said pair of terminals;
said winding having a center tap to which is applied a second alternating voltage to produce from said circuit an output at said common circuit point whose average voltage is proportional to phase difference between said alternating voltages.
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Abstract
Polyphase generators operating in parallel are provided with a circuit to protect against over or under excitation of any one generator. The circuit comprises means for developing a direct voltage proportional to the differential reactive current of each generator and also means for developing a direct voltage proportional to the rectified phase voltages, such voltages being summed and the result compared with a reference.
7 Citations
1 Claim
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1. A demodulator circuit comprising:
- a first pair of terminals for receiving an alternating voltage;
a first circuit branch connected between one of said pair of terminals and a common circuit point and comprising a first pair of diodes connected in series by like polarity electrodes thereof;
a second circuit branch connected between the other of said pair of terminals and said common circuit point and comprising a second pair of diodes connected in series by like polarity electrodes thereof, said electrodes being of opposite polarity to the interconnected electrodes of said first pair of diodes;
a Zener diode connected from the midpoint between said first pair of diodes and the midpoint between said second pair of diodes;
a transformer winding connected across said pair of terminals;
said winding having a center tap to which is applied a second alternating voltage to produce from said circuit an output at said common circuit point whose average voltage is proportional to phase difference between said alternating voltages.
- a first pair of terminals for receiving an alternating voltage;
Specification
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Current AssigneeWendell Calfee, William W. Billings
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Original AssigneeWendell Calfee, William W. Billings
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InventorsBillings, William W., Calfee, Wendell
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Primary Examiner(s)Huckert, John W.
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Assistant Examiner(s)Hart, R. E.
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Application NumberUS05/207,876Time in Patent Office588 DaysField of Search307/232,317,318 323/16US Class Current327/3CPC Class CodesH02H 7/062 for parallel connected gene...
