Development of a Deterioration Diagnosis Device for Arresters on Shinkansen Feeding Circuits

Abstract

Tsurugi YOSHIIResearcher, Tetsuo

Development of a detection device for deteriorated ZnO surge arresters at AC traction substations

“…Since surge arresters include a ZnO element inside an outer tube, as illustrated in Figure 1, the electrical circuit can be represented equivalently as a parallel circuit by the resistance R of the ZnO element itself and the capacitance C appearing in the vicinity of the outer tube. 4 As mentioned previously, only the total leakage current can be measured during operating hours and values of 0.20 mA to 0.77 mA have been reported as effective values. 3 Railroad companies have established maintenance standards for total leakage current measurements.…”

“…The aforementioned capacitance C negatively influences the measuring of the total leakage current in various ways. 4 We studied the characteristics of surge arresters during train service hours and found that, when the capacitive leakage current is dominant, even if only a slight harmonic component is included in the traction voltage, a large capacitive harmonic leakage current is generated as illustrated in Figure 2, which makes the resistive leakage current difficult to recognize. Also, the effective value of the total leakage current itself increases, giving rise to the possibility of erroneous determination.…”

“…A variety of methods for evaluating resistive leakage current have been proposed for improving the maintenance of ZnO surge arresters. Examples of these methods include: (a)canceling the capacitive leakage current by measuring the voltage waveform; (b)canceling the capacitive leakage current by acquiring a healthy voltage waveform in advance; and (c)monitoring fluctuations in the third‐order harmonic current component of the resistive leakage current …”