First, I will assert that all ideas presented here are mine and mine alone, derived independently of any other work being done by others in this field. That being said, this is my vision for a possible construction of a hall effect current measuring device to be used on high voltage systems. The basic design consists of hall effect magnetic sensors cast into a solid dielectric housing surrounding a high capacity through conductor. This construction keeps the sensors at a fixed known distance from the conductor which is key for proper calibration and consistent readings of the sensors. Also in the same dielectric housing is a power storage suoercapacitor, a microprocessor to gather and transmit the sensor data with infrared optical pulses, and a photovoltaic cell which will receive optical power transmitted up from the base and provide power to the processor and sensors. This dielectric housing will be connected to the base with two optical fiber links, one standard infrared fiber will carry sensor data, and the other will be a thicker optical shunt to carry high intensity light for power. There will be no electrically conductive connection from the base to the dielectric sensor housing. The base would contain a high intensity LED bank to transfer optical power to the sensor housing as well as an infrared photodiode to receive the sensor data. A second processor in the base will convert the sensor data into measurements of the current through the device, and will provide fiber optic or serial communications to mutifunctuion relay devices which can use the current measurements for protection and metering functions. This is one possible application of hall effect sensors for high voltage current measurement, which I believe could be made comparably rugged and reliable to traditional EHV oil filled current transformers, insofar as the hall effect sensor devices themselves are thoroughly tested prior to encasement.
This conceptual design can be considered GNU public, in case I or anyone else decides to hash out the design details.