5． Monitoring system to detect pantograph defects by sensors placed on overhead contact line

Monitoring systems have been developed for detecting pantograph defects such as step-shaped wear of the contact strips of a pantograph or abnormal aerodynamic upward force of a pantograph.
It has been confirmed that the systems have good detection accuracy by using test equipment at RTRI site.

Since it is difficult to detect pantograph defects while a train runs, large section of overhead contact lines and its equipment can be damaged by the defects. Therefore, we developed methods for detection of the defects by sensors placed on overhead contact line which monitor all pantographs running through their scope of observation. The one method can detect step-shaped wear on contact strips of pantographs; the other method, abnormality of aerodynamic upward force of pantograph.

To detect step-shaped wear on contact strips, firstly vertical and horizontal vibration are measured by sensors on the contact wire (Fig.1). Then, the step-shaped wear can be detected by analyzing the waveform of the vibration.

For detecting abnormality of aerodynamic upward force of a pantograph, droppers force and the gradient of the contact wire are measured to evaluate the average contact force between contact wire and a pantograph, which equals the sum of the static and the aerodynamic upward force of the pantograph. If the value of the average contact force exceeds the permissible range, this is detected as an abnormality.

In order to verify the detection accuracy of these systems, we carried out several tests at RTRI. The test results are shown as follows:

it is possible to achieve accurate detection of the step-shaped wear of contact strips for speed up to 120 km/h
it is confirmed that the abnormal aerodynamic upward force detecting system can measure the average contact force at sufficiently high precision (Fig. 2)

Fig.1 Illustration of the step-shaped wear detection sensor
Fig.2 Abnormal aerodynamic upward force detection