System for maintaining excitation of an alternator during excessive output current conditions
First Claim
1. A system for supplying power to a field winding to maintain excitation of an alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load and the field winding being supplied during normal operating conditions by a shunt type voltage regulator responsive to the output voltage of the generator, the system comprising:
- a current transformer having a primary winding in series with an output line of the generator, a secondary winding, and a tertiary winding shunted by a capacitance;
means for rectifying the voltage supplied by the secondary winding, the output terminals of the rectifying means being connected in series with the regulator output terminals to supply power to the field winding; and
control circuit means, connected to the output of the generator, and responsive to output current conditions to enable the rectifying means output during excessive output current conditions, said rectifying means output being disabled by the control circuit means in the absence of excessive output current conditions, whereby power from the rectifying means is supplied to the field winding only when an excessive output current condition exists.
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Accused Products
Abstract
A system for supplying power to a field winding to maintain excitation of an alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load and the field winding being supplied during normal operating conditions by a shunt type voltage regulator responsive to the output voltage of the generator. The system includes a current transformer having a primary winding in series with an output line of the generator, a secondary winding, and a tertiary winding shunted by a capacitance. A rectifier circuit rectifies the voltage supplied by the secondary winding, the output terminals of the rectifier circuit being connected in series with the regulator output terminals to supply power to the field winding. A control circuit, connected to the output of the generator and responsive to output current conditions enables the rectifier circuit output during excessive output conditions. Power from the rectifier circuit is supplied to the field winding only when an excessive output current condition exists. Additional circuitry prevents the enabling of the rectifier output if a decrease in generator voltage is accompanied by a decrease in generator frequency which substantially corresponds to a desired response of the voltage regulator. Another circuit disables the voltage regulator when the currents in the output lines of a multi-phase generator are not substantially equal during excessive output current conditions.
39 Citations
32 Claims
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1. A system for supplying power to a field winding to maintain excitation of an alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load and the field winding being supplied during normal operating conditions by a shunt type voltage regulator responsive to the output voltage of the generator, the system comprising:
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a current transformer having a primary winding in series with an output line of the generator, a secondary winding, and a tertiary winding shunted by a capacitance; means for rectifying the voltage supplied by the secondary winding, the output terminals of the rectifying means being connected in series with the regulator output terminals to supply power to the field winding; and control circuit means, connected to the output of the generator, and responsive to output current conditions to enable the rectifying means output during excessive output current conditions, said rectifying means output being disabled by the control circuit means in the absence of excessive output current conditions, whereby power from the rectifying means is supplied to the field winding only when an excessive output current condition exists. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A current transformer circuit comprising:
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a primary winding electrically connected in series with a load circuit through which an alternating current supplying said load flows; a secondary winding connected to an output circuit, said output circuit including elements having predetermined voltage ratings, the ratio of the ampere-turns of the secondary winding to the ampere-turns of the primary winding being approximately 2;
5; andmeans, including a tertiary winding, for limiting the voltage across the secondary winding to a level generally below said predetermined voltage ratings to protect said circuit elements, the voltage limiting means includes a capacitance electrically connected in shunt with the tertiary winding and forming a closed loop therewith, said primary winding being coupled to the secondary and tertiary windings only by electromagnetic induction, the tertiary winding being coupled to the primary and secondary windings only by electromagnetic induction, said tertiary winding having a resistance in the range of 3-7% of the reactance of the capacitance at the frequency of the alternating current.
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9. A system for supplying power to a field winding to maintain excitation of an alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load and the field winding being supplied during normal operating conditions by a shunt type voltage regulator responsive to the output of the generator, the system comprising:
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a current transformer having a primary winding in series with an output line of the generator, a secondary winding, and a tertiary winding shunted by a capacitance, the primary winding being coupled to the secondary and tertiary windings only by electromagnetic induction; and means for rectifying the voltage supplied by the secondary winding, the output terminals of the rectifying means being connected in series with the regulator output terminals. - View Dependent Claims (10, 11, 12)
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13. A system for supplying power to a field winding to maintain excitation of a multi-phase alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load, the field winding being supplied from a shunt type voltage regulator responsive to the output voltage of the generator during normal operating conditions, the system comprising:
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sense and boost means for sensing the current in each of the generator output lines and for impressing a voltage on the field winding during excessive output current conditions whose magnitude is substantially proportional to the number of generator output lines in which an excessive output current is flowing, said impressed voltage being sufficient to maintain the excitation of the generator during said conditions; and voltage regulator disabling means, responsive to the outputs of the sense and boost means, for disabling the regulator when the currents in the generator output lines are not substantially equal during excessive output current conditions, thereby halting the supplying of power from the regulator to the field winding, whereby the excitation of the generator is solely a function of the number of lines in which excessive output current flows. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A system for boosting the power supplied to a field winding to maintain excitation of an alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load, the field winding normally being supplied by a shunt type voltage regulator which regulates the excitation of the generator and the generator voltage according to a predetermined function of the generator voltage and generator frequency, the system comprising:
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means for boosting the field of the field winding during an excessive output current condition by impressing a voltage sufficient to maintain excitation of the generator upon the field winding during said condition; and control circuit means for enabling the boosting means on a decrease in generator voltage indicative of an excessive output current condition except when the decrease in generator voltage is accompanied by a change in generator frequency which substantially corresponds to said predetermined function of the generator voltage and generator frequency, whereby the system does not boost the power to the field winding when the voltage regulator reduces the excitation of the field winding due to a change in generator frequency. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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Specification