Typical application circuit of the single-phase electric power measurement system SM9903

Published:2011/5/10 19:08:00 Author:Christina | Keyword: Typical application, single-phase, electric power measurement | From:SeekIC

Typical application circuit of the single-phase electric power measurement system SM9903 is as shown. The constant of this watt-hour meter is 1600P/kWh, P corresponds to the 1kWh electricity output pulse, the basic measurement range is 5A, the maximum measurement range is 20A. The 220V alternating current gets through the 340μΩ manganese copper resistance R0 and changes into the current sampling signal, and this signal gets through the precision metal film resistor network and becomes the voltage sampling signal. The 220V alternating current uses the capacitance step-down method to supply power to the circuit, C4 is the step-down capacitance, VDz1 is the regulator tube of the +5V power supplier, VDz2 is the regulator tube of the -5V power supplier. Pin-8 outputs the active power integrated calculate pulse and this pulse is sent to the mechanical counter by optical coupler 4N32. The 32768Hz quartz crystals' frequency stability is 30X 10-6/oC, the equivalent inductance is 0.9mH, the load capacitance is 12.5pF, the equivalent resistance is 35 to 45kΩ. The C6, C7 are the integral capacitance. R8 uses the several-cycle fine-tune resistance. Rv is the 10K271 type thermistor that has the over-voltage protection function. LED is the red led.



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