Electronic three-phase watt-hour meter
AssigneeSiemens Aktiengesellschaft
InventorGunter Steinmuller
Life of this patent
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Abstract
An electronic multiphase watt-hour metering system containing time-division multiplying circuitry. A duty cycle modulator and a switching device are provided for each phase of interest, the output signals of which are combined and conducted to a current-to-frequency converter. The output frequency of the current-to-frequency converter is responsive to the rate of electrical power consumption from a multiphase transmission system. In one embodiment, the current-to-frequency converter is coupled at its output to an accumulating counting system for recording the total energy supplied to a load. There may further be provided an indicator responsive to the frequency of the current-to-frequency converter for providing a visual indication of the instantaneous rate of power usage.
Claims8
A circuit for measuring, by time-division multiplication, electrical energy which is delivered to a load by a multiphase transmission system having n symmetrical phases, the circuit being characterized in that there are provided:
- n means for producing n respective first signals, each of said first signals being responsive to a voltage at a respectively associated phase conductor of the multiphase transmission system;
- n means for producing n respective second signals, each of said second signals being responsive to a load current flowing through a respectively associated phase conductor of the multiphase transmission system;
- n switching means, each having first, second and control terminals, said first terminal being adapted to receive a respectively associated one of said first signals;
- n duty cycle modulator means each having an input terminal for receiving a respectively associated one of said second signals and an output terminal for providing an output signal having a duty cycle responsive to the amplitude of said respectively associated second signal;
- n means for coupling said output signal of a respectively associated duty cycle modulator means to said control terminal of a respectively associated one of said switching means for controlling said associated switching means in response to said output signal and thereby producing at said second terminal of said respectively associated switching means a respective time-division multiplied, energy proportional signal;
- combining means connected to each of said second terminals of said n switching means for producing a composite multiplier signal responsive to said n time-division multiplied, energy proportional signals at said n second terminals of said n switching means;
- current-to-frequency conversion means having an input terminal connected to said combining means for receiving said composite multiplier signal, and an output terminal for providing an output frequency signal responsive to said composite multiplier signal;
- and
- counting means having an input terminal connected to said output terminal of said current-to-frequency conversion means for receiving said output frequency signal, and producing an indication responsive to said output frequency signal.
Dependencies are inferred from the claim text.