Development of calibration apparatus for DC electric field measurement device

DC electric field is one of the most important parameters to evaluate the environment impact of DC power transmission project. In this paper a new apparatus for the calibration of shutter-type filed mills was developed. The parallel plate system can produce a calculable electric field with space charge. The principle and arrangement of the system are described in detail. Tests are performed to study several important factors that affect the accuracy of the calibration procedure. The test results suggest that the height of the field mill should be less than half of the spacing between the parallel plates. Normally electric-field meters that operate in the ground plane can be calibrated by making a hole in the center of the bottom plate and mounting the probe flush with the bottom plate. And calibration of ground-referenced field mills that operate above the ground plane can be made by supporting the probe at the center of the parallel plates with the handle. In this paper the difference between two mounting types are discussed and compared.