A crucial problem for railway companies is the detection of the critical points of the overhead line for predicting excessive wear of the contact wire and for helping maintenance activities. An innovative tool, based on wavelet multiresolution analysis, is proposed in this paper for on-line monitoring of the quality of current collection. Wavelet decomposition of data collected from different measurement systems (e.g. total traction line current or signals acquired from unconventional sensors) can perform an automatic analysis of the data collected and can detect a singular occurrence of arcing due to loss of contact of the pantograph. A relevant outcome of such an analysis is the evaluation of a quantitative index for checking the quality of the current collection via an integral analysis of the multiresolution signal decomposition. Examples of analysis from experimental data are reported in the paper.

Wavelet decomposition is proposed as an innovative tool for analyzing and classifying data acquired during test runs performed in Italy along the Florence-Rome high-speed railway line. It is based on the multi-resolution analysis typical of the wavelet transform: such analysis was applied to the traction current measurements. The wavelet tool allows automatic analysis of the data collected and detection of singular break arcs due to losses of contact of the pantograph. Software used for processing data was the Wavelet toolbox package developed inside a Matlab environment. Some examples of analysis from experimental data are reported in this paper.

A new measurement system able to detect the occurrence of arcing between the pantograph and the overhead contact line was studied and set up. The system uses photomultiplier tubes to measure the duration of the ultraviolet emission due to electric arcing. The major advantages of the system proposed are its non-invasivity with respect to the pantograph equipment, its reliability and its low cost. Correlation with data acquired during high-speed test runs from different sensors (e.g. currents measured in an equipotential wire between the front and the rear pantographs, images acquired from a TV camera), provided the opportunity to perform an efficient calibration and an analysis of selectivity of the phototube sensor. Data from the phototube sensor along with various other information lead to the definition of a reliable index for evaluating the quality of the current collection. The determination of such an index has primary relevance for maintenance activities, for computing the minimal thrusts to be applied to the pantograph at different speeds and for testing new materials for overhead contact wires and collector strips.

A new measurement system able to detect the occurrence of arcing between the pantograph and the overhead contact line has been studied and set up. It uses photomultiplier tubes in order to measure the duration of the ultraviolet emission due to electrical arcing. The measurement equipment was installed on board of an ETR500, a high-speed train of Italian Railways, with a double pantograph. A software package was developed in LabWindows/CVI environment for recording and elaborating data acquired from the measurement chain. In the paper the software for acquiring and processing data in order to validate the phototube sensor and to evaluate the status of the pantograph-catenary interaction is presented, along with experimental results.