| 摘要 |
<p>21 ME-5227 An electronic kilowatt-hour meter having internal error correction is disclosed for metering electrical power and energy consumption in a single phase or polyphase electrical system. A comparator compares an analog signal which is proportional to the voltage in the system with a relatively high frequency triangular waveform. The output of the comparator which is a pulse width modulated signal having a pulse duration proportional to the amplitude of the voltage in the system is multiplied by a signal which is proportional to the current in a system. The output of the multiplier is integrated to thereby provide a signal which is proportional to the energy consumed in the system. The output of the integrator is converted to a pulse train having a frequency which is proportional to the amplitude of the output signal of the integrator, and hence is proportional to the kilowatt hours consumed in the electrical system. In order to provides error correction, the phase of the analog signal which is proportional to the voltage in the system is shifted with respect to the phase of the triangular waveform by reversing the connections of these respective signals to the input terminals of the comparator. This is done each time an output pulse is generated by the analog-to-pulse-rate converter. Thus the integrator alternately integrates up and down to thereby correct any offset errors in the system.</p> |
