LAUSR

The online impedance serves as a key parameter to evaluate the operating status and health condition of many critical electrical assets. The inductive coupling approach is a superior method to extract the online impedances of the electrical assets, as it does not have any physical electrical connection to the energized electrical asset under test. However, the existing setup of the inductive coupling approach usually uses two inductive probes, with one as an injecting inductive probe (IIP) and the other as a receiving inductive probe (RIP), and consequently, it is unable to simultaneously measure the online impedances of electrical devices distributed in multibranch cables. In addition to the prevalent two-probe setup, a method involving a three-probe setup, with one IIP and two RIPs, has also been reported. However, its applicability is limited to the simultaneous measurement of the online impedances of electrical devices distributed in two-branch cables. Also, the three-probe setup ignores the parasitic components of IIP and RIPs, which may affect the accuracy of online impedance measurement. To overcome the aforementioned limitations, this article proposes a multiprobe inductive coupling method for the simultaneous measurement of the online impedances of electrical devices distributed in more than two branches of cables. The measurement setup of the proposed method consists of one IIP, multiple RIPs depending on the number of devices to be measured, and a computer-controlled signal generation and acquisition system. Using a circuit with three branches as a test sample, the accuracy and the reliability of the proposed method have been verified by experiments.