PCMS Engineering worked with a UK tram operator to carry out an investigation of the pantographs – the apparatus mounted on the roof of an electric tram collect power through contact with an overhead catenary wireon – on one of their trams following instances of wear on the pantograph horns.
There was evidence of wear due to abrasion and impacting abrasive wear, which can be caused by abnormal interaction with the overhead line equipment (OLE) contact wire. The impact damage was thought to be caused by the pantograph horns striking the knuckle -a mechanism for connecting railway cars in a train. The abrasive wear was apparent for some time but appeared to be worsening over time.
In order to try to detect the location of where potential wear could be developing, PCMS mounted four high-definition cameras to monitor the pantograph during operation along the full length of the tram route.
Two tri-axial accelerometers were mounted to determine if any abnormal forces were being induced to the pantograph; one accelerometer was mounted to the frame supporting the pantograph and the other was mounted directly to the pantograph.
To ensure continuous/real-time data was captured, the 2600 was configured to acquire transient data during the test period.
Video footage showed a possible connection between the pantograph horns and the adjacent overhead cable at a location under a bridge. However, the perspective of whether the cable actual makes contact with the horns is difficult to detect through the camera. PCMS recommend further investigation to determine the validity of the observation. The distances between the cables was determined by comparing the span of the pantograph.
The recorded footage between the two locations showed a distinct impact on the horns of the pantograph. A detailed investigation into the exact location of this merging cable was recommended.
Due to the pantograph deflection in the video footage observed between two stations, the final recommendation was to investigate into the possible cable connection along this route.