EMC (Electromagnetic Compatibility) is an important part of any rail project, be it recommissioning or refurbishing rolling stock, track and infrastructure renewals, electrification and stabling projects, or adding additional electronic items to existing systems.
The management of EMC, from a risk-based viewpoint, is something that needs to be carried through all of the stages of a project; ideally from conception to completion. EMC is a specialist subject that not everyone is comfortable with – therefore knowing one’s responsibilities is key to a successful and stress-free project.
There are three scenarios that are common in the rail sector and project managers and engineers need to be aware of the main EMC considerations.
In all scenarios, the following points are key to ensuring a ‘no surprises’ EMC process:
- What is the EMC environment?
- What are the EMC requirements, and do they match the environment?
- Is there an EMC plan?
- Are there recognised quality/competency systems in place?
- How will deviations from the plan, the specifications, or the declared environment be resolved?
- What documents will be produced and are they sufficient to demonstrate compatibility?
In this scenario, a new fire alarm system is being installed as part of a station upgrade. Following the points above, the main EMC activity for this kind of situation is to ensure that the fire alarm system is suitable for its environment. Note that this covers the whole system, not just the sensors, so routing of cabling is also important.
Risks – Fire alarm fails to function as intended and there is a situation where a fire occurs, and the alarm does not go off, with the associated safety implications. There is also a risk that the fire alarm goes off when there is not a fire, causing loss of service in the station. These are both EMC risks, but have rather different severity levels.
Responsibility – There is a responsibility on the fire alarm system manufacturer to supply equipment that is suitable for the environment in which it is used. This can be achieved by the application of harmonised standards and a CE mark – a legal requirement for any electronic product being placed on the market. There is also a responsibility for the person who is looking after the upgrade project as a whole as it is an offence to knowingly bring into service a non-compliant installation.
Regulation – Apparatus and installations are both covered by EMC directive 2014/30/EU. Product-specific standards for fire alarms are available and, where applicable, should be compared to the expected rail environments given in the EN50121 series of standards. Documentation for fixed installations should reflect that this has been carried out appropriately using a risk-based approach.
Consider an existing maintenance depot that is being repurposed to be able to repaint rolling stock. Again, the questions require answering to ensure that all will be well when the depot is recommissioned. Of particular importance in this kind of scenario is ensuring that both the project and the suppliers of large apparatus understand what is required of them in terms of EMC, so that overall project costs can be kept down.
Risks – Apparatus or systems that are connected to the new parts of the maintenance depot interfere with existing systems. For example, variable-speed drives in fume extractors produce harmonics which, if uncontrolled, can couple into adjacent sensitive cabling such as that used for a depot protection system. This is just one example and, with many items of apparatus in a small area (there is never enough space), this situation can be replicated throughout a surprisingly large area.
Responsibility – The supplier of the equipment (in this case, the fume extraction system) is responsible for supplying equipment that is suitable for the environment in which it is used. As with scenario 1, the responsibility lies with both the manufacturer and the person bringing the installation into service.
Regulation – Apparatus and installations are both covered by EMC Directive 2014/30/EU. Generic standards for industrial environments are often used for equipment such as variable-speed drives, so, as with Scenario 1, the declared standards should be compared to the expected rail environments given in the EN50121 series of standards.
If a track alignment change is planned for an electrified railway, the EMC environment is unlikely to change dramatically; there was an electrified line before the works, and there will be one after, just in a different physical location.
The rail EMC environment is sometimes taken as extending 10 metres from the track centerline, therefore larger alignment changes may result in nearby areas coming within 10 metres of the track when previously they were not. Also, of consideration may be additional enabling works such as moving signalling cables, points heating systems and so on.
Risks – With no new apparatus to be supplied in this scenario, the requirements focus on the changes made to the electromagnetic environment. This then encompasses a consideration of EMC risk to third parties or neighbours, particularly if the zoning areas have changed due to the track moving.
Responsibility – There is a responsibility on the person in control of the works to ensure that the changes comply with the essential requirements of the EMC Directive.
Regulation – A form of EMC control or management is likely to be required to ensure that the finished project is compliant when it is brought into service.
So, in summary, the key points when undertaking any railway project from an EMC point of view are to ensure that both any procured equipment and the whole project are compliant. Suppliers to the rail sector should ensure that their equipment is suitable for the environment into which it is being installed and be able to provide such evidence that is required by projects. Evidence will most likely take the form of a Declaration of Conformity, which will state that the apparatus meets the requirements of appropriate and suitable standards and that the CE mark can be applied. For manufacturers – watch out for standards changing, they need to be correct at the point of placing on the market, not just when the product is launched.
For project managers, project directors and others with EMC responsibility for projects, a proactive framework of control, review and assessment is the easiest and most appropriate way to get to completion without an EMC headache.
This article was written by Dr Rob Armstrong, expert services and training manager at Eurofins York (formerly York EMC Services).