A hotstick instrument for estimation of the potential of an HVDC conductor

In 1989-1990, New England Power Service Company (NEPS) and Bonneville Power Administration (BPA) jointly sponsored the UHVDC Live-Line Voltage-Estimator Project with three principal goals: to develop a technology which would permit moderately accurate estimates of the DC potential of a UHVDC line without requiring an electrical connection to ground or any other reference point; to develop an instrument embodying this technology which could be applied by a lineman in the field and to demonstrate that the system functioned as expected; and to develop and incorporate in the instrument a technique for estimating the induced AC component of the potential. As demonstrated at the BPA outdoor test facility on August 15, 1990, the first goal has been fully met. The authors report a demonstration that a properly located field mill can determine the DC potential to better than 10% of full scale over a range from 0 to ±500 kV, even in the presence of wind and corona. Solutions to the remaining pair of goals have been defined, and an effort is underway to develop a field-hardy engineering prototype of a production instrument