The online impedance serves as an essential parameter to evaluate the operating status and health condition of many critical electrical systems. Because of its non-contact nature and ease of on-site implementation, the inductive coupling approach is an outstanding method for online impedance measurement. The inductive coupling approach usually adopts a two-probe measurement setup. In some practical situations where a system under test (SUT) is exposed to significant electrical noise and power surges, the existing two-probe measurement setup lacks the necessary signal-to-noise ratio (SNR) and front-end protection to measurement instruments, which, as a consequence, makes its use challenging. To overcome this challenge, an improved two-probe measurement setup is proposed in this article. The proposed two-probe measurement setup incorporates signal amplification and surge protection modules, thereby improving its SNR and enhancing its ruggedness. By performing a number of tests that cover different frequencies and various SUTs, the accuracy and the reliability of the proposed two-probe measurement setup have been validated by experiments.

Inductive Coupling,Electrical System,Online Impedance Measurement,Two-Probe Measurement Setup