| 摘要 |
A monitoring system for continuously monitoring the ground conductor of an electrical cable having power conductors and a pilot wire in addition to the ground conductor. An a.c. test signal is connected onto a loop comprised of the ground conductor and pilot wire and a terminating impedance. A current transformer samples the test signal on the ground conductor and checks its magnitude. By making the transformer impedance considerably lower than the mutual inductance between the ground conductor and pilot wire, large, expensive blocking impedances are not required to prevent the test signal from following sneak paths from the test loop to earth ground.
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