| 摘要 |
A system for measuring and recording DC electric field data at multiple locations using field mill sensors having periodically exposed sensing electrodes to provide cyclic signals, relating to the field amplitude and polarity, which are demodulated by phase synchronous detection to provide measurement of the field at an indicator which is calibrated and checked by intermittently applying to a rotor electrode a DC voltage determine calibration data for sensor indicators. Phase and frequency adjusting circuits control sensor motor/rotor speed and the signals generated for optimum polarity and amplitude measurement. Motor speed is controlled to minimize effects of external noise. Contamination degradation of sense electrode insulators is measured by comparing output signals as the rotor is changed between rotating and stopped conditions. Metal modulator parts are finished with extremely smooth polished surfaces. A central computer communicates with all remote sensors to record data and to monitor and control system operation and to provide appropriate alarms related to electric field intensities and to the operating condition of the sensors.
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