| 摘要 |
<p>1,079,374. Automatic control systems. WESTINGHOUSE ELECTRIC CORPORATION. Feb.16, 1965 [Feb.27, 1964], No.6645/65. Heading G3R. In a system including a plurality of polyphase sources 1, 2 operating in parallel, a load unbalance detecting arrangement includes a current transformer loop circuit 8, 8, 9, 10 for producing a signal current proportional to the difference in load currents of the sources 1, 2, and a voltage sensing circuit 11 for each power source, the circuit 11 including means for deriving voltages in phase and in quadrature with the signal current and means for vectorially combining the derived voltages with the phase voltages of the power source. The output from the circuit 11 may be applied to a voltage regulator 7 associated with the relative power source so that the unbalance is automatically corrected, or it may be applied to an indicating or protective device. Each circuit 11 includes a capacitor 12 and a resistor 13 energized by the signal current, a first transformer 14 having its primary 16 connected across the capacitor 12 and having secondaries 17, 18, 19, and a second transformer 15 having its primary connected across the resistor 13 and having secondaries 21, 22 which together with the secondaries of transformer 14 are connected as shown to the output phase lines of the power source. The Specification describes with reference to a vector diagram Fig. 2 (not shown) how voltages in phase with and in quadrature with the signal . current are derived, and how these derived voltages are combined with the phase voltages to modify the voltage to which the regulator 7 responds, whereby there is maintained a proper reactive load division between the sources 1, 2. By suitably modifying the connections, the circuit 11 . may be used to respond to unbalance of real load instead of reactive load. The circuit 11 may also be modified to provide a D. C. output signal with polarity and magnitude determined by the direction and magnitude of the unbalance Figs.3 to 5 (not shown).</p> |
