| 摘要 |
An electronic wattmeter monitors the current and voltage of power lines and generates unitized voltage pulses at a frequency that is proportional to the average power carried by the lines. The wattmeter includes a current transducer that is inductively coupled to the monitored power lines. The transducer generates an induced current that is representative of the current that flows in the lines. The current transducer includes a magnetically permeable frame which has two magnetically permeable, spaced parallel leg members and a magnetically permeable cross-member that is detachably affixed between the leg members. The monitored power lines pass through an aperture defined by the leg members and cross-member of the frame and the frame additively applies the magnetic fields of the conductors to a coil that is inductively coupled to the frame. The coil generates an induced current corresponding to the current of the conductors. A multiplier samples the induced current at a rate defined by the line voltage and generates an output voltage signal that has an average intensity that is representative of the product of the line voltage and the current of the lines. An integrator successively integrates the output voltage signal of the multiplier to a particular magnitude and generates a unitized pulse for each integration up to the particular magnitude. An optical isolator generates an output signal that is modulated by the unitized pulses of the integrator and that is electrically isolated from the line voltage of the power lines.
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