EMC test service checks out railway equipment

A precompliance EMC test service is available for railway rolling stock and equipment to ensure compliance with all aspects of the harmonised EN50121 standard.

With the increasing introduction of high-power electronic equipment, together with complex microcontrollers and a multitude of other electronic devices being installed on trains and other rail vehicles, electromagnetic compatibility within the rail environment has become a critical issue in every aspect of the design and implementation of train and rail-associated apparatus.

This has subsequently led to the mandatory requirement that all new railway applications, including stock (eg a single commercial railway unit), traction stock (eg electric and diesel locomotives etc), hauled stock (eg.

independent passenger coaches and freight wagons), main-line vehicles (eg high-speed trains, freight trains etc designed to operate between cities) and urban vehicles (eg underground train sets, trams, LRVs etc), must be tested, among other things, for compliance with the European and British Standard (BS) EN50121.

According to James Daniels,EMC Rail Test Engineer at EMC Solutions: "The directive EN50121 addresses the three main aspects of the railway system that EMC concerns: the effect of the railway system on the surrounding environment; the effect of the railway system on signalling and communications equipment; and the ability of railway equipment and related apparatus to remain unaffected by the inherently severe environment within which it is intended to operate.

It is further stated that the infrastructure controller and the train/rolling stock operator must take all reasonable measures to ensure that their actions and equipment do not compromise reliability due to EMI, under normal operating procedures".

To ensure that these issues are satisfied, and to help alleviate the concern of health and safety in an increasingly hazardous environment, it is now imperative that any newly introduced rail vehicle and associated equipment is tested to ensure that both the electromagnetic emissions and the level of immunity to external EMI are within the specified limits.

This EMC testing now forms a compulsory part of the assessment undertaken by the small number of vehicle acceptance bodies, within the UK, that approve all applicable equipment suitable for use on the nation's extensive rail network.

EMC Solutions' services include the precompliance testing of the electromagnetic compatibility of rolling stock (train and complete vehicle), and electromagnetic compatibility of rolling stock (apparatus), EN50121-3-1 and EN50121-3-2, respectively, encompassed by the overall product specification of EN50121, to the standards required by VABs to authorise the vehicle or equipment's suitability for use on the railway.

These specifications can be suitably interpreted and adapted by the company's fully qualified engineers to enable their application to any relevant item of rail-associated equipment.

The individual tests that form constituent parts of EN50121, conducted by EMC Solutions to ensure compliance with the standard, usually include the following elements (dependant on the type of vehicle or rail-enabled system under test): EN55011 Class B for radiated emissions (if appropriate); EN61000-4-6 Level 4 for conducted immunity; EN61000-4-4 Level 4 immunity to fast transient bursts; EN61000-4-2 Level 4 immunity to electrostatic discharge; and EN61000-4-3 immunity to radiated fields.

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