K.Y. Lee

A Fiber Bragg Grating Sensor System for Train Axle Counting

Railway signaling facilitates two main functions, namely, train detection and train control, in order to maintain safe separations among the trains. Track circuits are the most commonly used train detection means with the simple open/close circuit principles; and subsequent adoption of axle counters further allows the detection of trains under adverse track conditions. However, with electrification and power electronics traction drive systems, aggravated by the electromagnetic interference in the vicinity of the signaling system, railway engineers often find unstable or even faulty operations of track circuits and axle counting systems, which inevitably jeopardizes the safe operation of trains. A new means of train detection, which is completely free from electromagnetic interference, is therefore required for the modern railway signaling system. This paper presents a novel optical fiber sensor signaling system. The sensor operation, field setup, axle detection solution set, and test results of an installation in a trial system on a busy suburban railway line are given.

Magnetoelectric Smart Current Sensors for Wireless Condition Monitoring of Train Traction Systems

Condition monitoring of train traction systems has become increasing crucial to train operators in terms of safety, reliability and availability. Current signatures governed by electric motor drives of train traction systems are physically valuable to represent the operating conditions of the train traction systems. However, the long train length, tough and complex system connections, critical measuring locations, high-voltage and heavy-current environment, etc. always impose great difficulties when installing wired condition monitors involving active current sensors (e.g. current transformers, Hall sensors, Rogowski coils, etc.) which are often accompanied with the need of power supplies and signal conditioners. In view of this, we have developed power supply-free, signal conditioner-free, surface mount-type magnetoelectric smart current sensors and integrated them with a 4-channel, 2.4 GHz wireless communication (transmitter and receiver) unit. Four pairs of sensors and wireless transmitters have been installed on electric cables associated with the four electric motor drives situated underneath the 2nd, 5th, 8th and 11th cabins of a 12-cabin mainline train running between Hong Kong and Shenzhen, China. A 4-channel wireless receiver has been housed in the driver cab to provide real-time, wireless monitoring of the current signatures of the four electric motor drives. In this paper, the development of the sensors and wireless communication unit is described, and the field installation and test results are presented.