Electronic watthour meter circuit
AssigneeWestinghouse Electric Corp.
InventorLanson Y. Shum
Life of this patent
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Abstract
An electrical energy measuring circuit is responsive to two analog signals proportional to the voltage and current components of an electrical energy quantity to be measured. Voltage-to-frequency converters convert sampled DC voltages into first and second pulse trains having frequencies proportional to the peak voltage levels and the related levels of active or reactive current. A binary counter is incremented at a fixed rate by the sampling pulses. The binary counter is periodically reset by one of the pulse trains. The accumulated counter value is applied to a down binary counter which counts down at the frequency of the second pulse train. Borrow pulses are generated to provide an indication of electrical energy consumption.
Claims10
An electronic watthour meter circuit responsive to the voltage and current components of an AC electrical energy quantity to be measured, said circuit comprising:
- means producing a first sinusoidal voltage signal in response to said voltage conponent;
- means producing a second sinusoidal voltage signal in response to said current component;
- means producing a sampling pulse in response to each cycle of said first voltage signal;
- sampling means controlled by said sampling pulse for sampling said first and said second voltage signals during each cycle thereof;
- voltage-to-frequency converter means producing first and second pulse trains each having a frequency responsive to the sampled values of said first and said second voltage signals, respectively;
- binary counter means having a counter input, a reset input, and binary outputs, said counter input receiving said sampling pulse and said reset input receiving said first pulse train such that said output produces a binary output inversely proportional to the sampled value of said first voltage signal during each cycle of said first voltage signal;
- and
- down binary counter means having data inputs, a clock input and a borrow output, said data inputs receiving said binary counter outputs, said clock input receiving said second pulse train such that said borrow output produces pulses responsive to the sampled values of said second voltage signal divided by the inverse values of the sampled values of said first voltage signal, whereby said borrow output pulses are representative of the electrical energy quantity to be measured.
Dependencies are inferred from the claim text.