A new approach for location of electrical faults along power transmission lines has been proposed in this paper. In the new approach, the electrical current signals of a fault at various locations along a transmission line are introduced into two fiber optical cables that could exhibit two different propagation speeds, and the fault location is found by using the time differences of arrival of the output signals from the two optical cables. To evaluate this approach, two types of experiments, one with square pulse generators for relaying the signals before being introduced into the optical cables and the other without any relay, have been carried out and the results show the location can be found with an error less than 10 m for a simulated power transmission line.

For Partial Discharge (PD) measurement, not only detecting the signal magnitude of PD is enough for evaluating the insulating constructions of HV equipment such as GIS, GIL, power cable, and cable joint, but also localization of the PD position is important to them. PD localization can help to find out the defect point effectively and determine the cause of PD, improve the manufacturing process, and increase the insulating properties. This paper describes multiple new methods of PD localization including 1) use of metallic foil electrode sensors, 2) excitation of X-ray radiation, 3) application of acoustic emission sensor, applied to a EHV prefabricated joint in a length scale of about 2m long. Comparing with the conventional PD localization for long size of cable, it is more difficult to locate a PD for the short size of joint due to the pulse reflection, the pulse propagating route and the difference of propagating velocity, based on the materials and shape of the part units of the joint. Several successful PD localization shown that the method can locate PD with sufficient accuracy.

With an example of PD localization for EHV cable joint on site, multiple method of PD localization is studied in this paper, including (1) method of using metallic foil electrode sensors, (2) method of excitation by X-ray radiation and a foil electrode sensor, and (3) method of applying acoustic emission sensors and a foil electrode sensor. Compared with the conventional method of PD localization for long distance cables of more than hundreds of meters, it is more difficult to localize a PD for a pre-fabricated type of joint of only a short length of around 2 m, due to problems in measurement such as the disturbance of pulse reflection, the complicated route of pulse propagation and the difference of pulse propagation velocity. The results of the example also show that this multiple method can give a high accuracy of PD localization.