Abstract: The invention relates generally to downhole measurement tools having a regulated voltage power supply and methods of use thereof. The downhole measurement tools are associated with electrical submersible pumps for providing a stabilization technique for a five (5) volt power supply over a wide temperature range. A voltage regulator circuit for the downhole measurement tools has a temperature dependent resistance to adjust the feedback of the regulated voltage to compensate for the temperature coefficient effects of the other components in the regulator circuit.

Abstract: A downhole measurement tool circuit and method to balance fault current in a protective inductor, which keeps an alternating current balanced in a protective choke during a phase-to-ground fault condition in a power cable or a downhole motor of an electrical submersible pump. The downhole measurement tool circuit and method cause a conducting of current during the negative polarity voltage portions of a phase-to-ground fault condition, but do not cause a conduction of negative polarity voltage during use of a negative polarity megger.