Application of new optical load cells for in-line measurement of pantograph-catenary contact force

The contact force between pantograph and catenary is a parameter needed to evaluate the quality of the dynamic interaction of the two systems. The in-line measurements of this parameter have always been very hard due to the particular work condition of pantograph and catenary. High voltage (from 1.5 kV dc for underground trains to 25 kV ac for high-speed trains) is the main obstacle to be overcome for the measurement setup: if traditional sensors are used (electrical load cells), an adequate electrical insulation of the whole measurement setup is necessary, making it more complex and more expensive. In this work, the use of fiber Bragg gratings (FBG) load cells, designed on purpose, is presented. The main advantage of this kind of sensor is the intrinsic electrical insulation, which makes it very suitable for the measurement of pantograph-catenary contact force. In the following sections, laboratory tests and in-line tests using the optical load cells to measure the pantograph-catenary contact force will be discussed, proving the good work of the load cells and the possibility to obtain an easier measurement setup for the considered application.