A miniaturized space-potential DC electric field meter

The authors describe a space-potential electric field meter designed to measure the field under a DC transmission line in the presence of distorting objects. The meter uses fiber-optics to couple a small measuring probe to a remote readout device, so as to minimize field perturbation due to the presence of the probe. By using coherent detection, it has been possible to produce an instrument whose operating range extends from about 30 V/m up to about 500 kV/m without the need for range switching on the probe. The electrical and mechanical design of the meter is described, and data from laboratory and field tests are presented