System and method for an AC powered downhole gauge with capacitive coupling

摘要

Borehole instruments are powered by AC instrument power transmitted on all three phases of a power cable concurrently carrying three phase motor power, the instrument power transmitted at a multiple of the motor power frequency and having a corresponding fraction of the motor power voltage, and received via a capacitive coupling sufficient to withstand high-voltage cable insulation testing. The phase-to-neutral motor power provides approximately the same power level to the borehole instruments if a phase shorts to ground.