Electronic type watthour meter including automatic measuring-error correcting function
First Claim
1. An electronic watthour measuring apparatus comprising:
- power-to-frequency (W/F) converting means for converting electrical power supplied from a power source into a first frequency signal having a first frequency and a measuring error, corresponding to the electrical power;
frequency dividing means for dividing the first frequency of the first frequency signal in accordance with a controlled dividing rate to obtain a second frequency signal having a second frequency lower than the first frequency of the first frequency signal;
means for calculating a difference between the first frequency of the first frequency signal and a reference frequency contained in a reference signal derived from a reference watthour meter while measuring the same electrical power from the power source; and
means for setting said controlled dividing rate and applying said controlled dividing rate to the frequency dividing means in accordance with the difference between the first frequency and the reference frequency, whereby frequency-dividing operation by the frequency dividing means is controlled based on the dividing rate set by the setting means so as to eliminate the measuring error contained in the electrical power measured by the electronic type watthour measuring apparatus.
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Accused Products
Abstract
An electronic type watthour measuring apparatus equipped with an automatic measuring-error correcting circuit. The electronic type watthour measuring apparatus includes: a power-to-voltage (W/V) converter for converting electrical power supplied from a power source into a voltage signal corresponding to the electrical power; a voltage-to-frequency converter for converting the voltage signal derived from the W/V-converter into a frequency signal corresponding to the voltage signal and indicative of the electrical power with an error; a calculator for calculating a difference between the frequency of the frequency signal and a frequency of a reference signal derived from a reference watthour meter while measuring the same electrical power from the power source; and a controller for controlling the voltage signal outputted from the W/V-converter based on the difference in the frequencies of both the frequency signal and reference signal so as to eliminate the error contained in the electric power measured by the electronic type watthour measuring apparatus.
40 Citations
5 Claims
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1. An electronic watthour measuring apparatus comprising:
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power-to-frequency (W/F) converting means for converting electrical power supplied from a power source into a first frequency signal having a first frequency and a measuring error, corresponding to the electrical power; frequency dividing means for dividing the first frequency of the first frequency signal in accordance with a controlled dividing rate to obtain a second frequency signal having a second frequency lower than the first frequency of the first frequency signal; means for calculating a difference between the first frequency of the first frequency signal and a reference frequency contained in a reference signal derived from a reference watthour meter while measuring the same electrical power from the power source; and means for setting said controlled dividing rate and applying said controlled dividing rate to the frequency dividing means in accordance with the difference between the first frequency and the reference frequency, whereby frequency-dividing operation by the frequency dividing means is controlled based on the dividing rate set by the setting means so as to eliminate the measuring error contained in the electrical power measured by the electronic type watthour measuring apparatus. - View Dependent Claims (2, 3, 4, 5)
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Specification