Described in this paper are the new devices which convert three-phase active-power (0-1kW) or reactive-power (0-1kVar) to DC voltage (0-5V) and pulse-frequency (12-24c/s).
The P-V converter utilizes the time division multiplier, the essential circuits of which are a voltage-controlled linear oscillator and a switching circuit. The P-f Converter includes the P-V converter and the V-f converter, the circuit of which is also a voltage-controlled linear oscillator. For this oscillator, we developed the astable multivibrator whose discharging current is proportional to the control voltage.
The performance of these converters are nearly equal to that of Class 0.2 indicating wattmeter. On the other hand, these converters are protected well against the surge voltage (5kV, 1×40μs) and the short circuit current (40×rated current, 1sec), etc., which might occur in the power line.
The P-f converter is made use of in frequency-division-multiplex telemetering. The P-V converter is made use of as the pre-converter for both analog and digital measuring-and controlling-equipments. Because of the high level output, the P-V converter mentioned here can be connected directly to an A-D converter.
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