This paper describes a diagnostic system for pantograph and catenary condition based monitoring, based on the measure of collector accelerations. The proposed set-up is cheap and feasibly installable on commercial service trains, with the aim to improve the present-day scheduled catenary and pantograph maintenance, and to lead towards an event-driven maintenance. Meaningful indications about pantograph-catenary interaction are obtained by the analysis of collector accelerations, summary values are computed in real time and compared with alarm limits