Improved configurations of sensors for the measurement of tower footing resistance.

摘要

Relatively low footing resistance of a transmission line pole is desired as it affects switching surge performance and surges caused by lightning strikes to power transmission lines. Safety of personnel and animals in the vicinity is also related to the footing resistance. The footing resistance must be measured periodically because it changes with season. There are limited commercial equipment available which can measure tower footing resistance without disconnecting overhead static wire. In this research, a "Single Point System" designed earlier at Tennessee Technological University was used to measure the footing resistance of transmission poles even with static wire connected.;In this thesis, different magnetic field sensor configurations were developed to measure tower footing resistance using relatively low values (less than 3 mA) of current. Three configurations viz. a compact Single Point System (SPS), Single Sensor System (SSS), and Parallel Sensor System (PSS) based on previously developed "Single Point System (SPS)" were developed. Application of a compact Single Point System to measure resistance of a grounding grid was also studied.;Tower footing resistance on the laboratory pole was varied from 10 to 200 ohm and tested using compact SPS, SSS and PSS. An error of +/- 6.55% and +/- 8.86% was observed on ungrounded and grounded field poles respectively when the compact Single Point System (SPS) was employed.