Metros & Railways

Electrification as a form of traction for railways emerged towards the end of the 19th century. 25 kV, 50 Hz AC has become an international standard for railway electrification. Modern locomotives have various electrical, electronic and power electronic components for power conversion, control,  passenger information, protection and safety. Some components perform supervisory roles and monitor the working of the entire electrical and electronic systems in the locomotive.

Vacuum circuit breakers or SF6 gas circuit breakers are used for protection and interrupting short-circuits in the overhead catenary system that are and transient in nature. In older locomotives, On load tap changers (OLTCs) are used to regulate the input voltage to the main transformer and control the speed of the locomotive. In modern locomotives, OLTCs are gradually being replaced with thyristor converters that are less susceptible to failures, require less maintenance, and offer smooth speed control. There are various proprietary electronics assemblies present in the locomotive, such as converters, auxiliary converters, drive control units, vehicle control units, I/O modules, communication modules, etc. They perform various functions, such as power distribution in the locomotive, communication between various devices, regulating the power to the axles, etc.

To ensure a reliable operation and a long service life, testing of various components used in electric traction applications is necessary. Circuit breakers and OLTCs have typical tests that are performed, such as speed and travel measurements, contact timings and bounce, current and voltage characteristics, etc. The proprietary electronics hardware needs to be tested as per the manufacturer’s specifications.

Crest manufactures a full range of testing products for railways and OEMs for ensuring the quality of the product before installation and for periodic maintenance to ensure optimum performance of their assets.

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