What EN 50155 is, and why rail projects treat it as a gate
EN 50155 is the CENELEC standard for electronic equipment used on rolling stock. Its full title is Railway applications – Rolling stock – Electronic equipment; the current editions are 2017 and 2021, and its international counterpart is IEC 60571. It covers equipment that controls, regulates, protects, diagnoses or powers something on the vehicle – which is precisely where a network switch sits.
Rail projects treat it as a gate rather than a nice-to-have because a train is not a factory with a bad climate. The failure modes are different. Vibration works on the connector rather than the housing. The supply rail collapses when the traction converter switches. Condensation forms on a cold morning and then the vehicle runs into a warm tunnel. Insulation has to hold at voltages that no general industrial product is designed for. A switch that has only met general industrial standards has not been tested against any of these.
The five requirement areas buyers keep coming back to
Almost every technical clarification in a rail tender reduces to five items, and each one is expressed as a class rather than as a single figure.
· Operating temperature, expressed as an OT class rather than a bare temperature range.
· Supply voltage, expressed as a window around the nominal battery or DC bus voltage.
· Supply interruptions, expressed as S classes – how long the equipment rides through a loss of supply without resetting.
· Shock and vibration, expressed as an EN 61373 category determined by the mounting position.
· EMC and insulation, tested to the EN 50121 series and designed along EN 50124-1.
Figure 1 – EN 50155 in five numbers: the requirement areas, the OT temperature classes, and the supply window a nominal 110 V DC system actually presents to the equipment.
EN 50155, EN 50121 and EN 61373: who does what
Three standards are usually quoted in the same sentence and they answer three different questions. When a supplier quotes all three, ask which document supports which.
| Standard | What it covers | What a buyer should see |
|---|---|---|
| EN 50155 | The equipment itself: temperature, supply, interruptions, insulation, documentation and testing | A type test report that names the declared OT and ST classes |
| EN 50121-3-2 | EMC on board the vehicle: emissions and immunity in the rolling-stock environment | EMC test data for the rolling-stock environment, not a general industrial report |
| EN 50121-4 | EMC for signalling and trackside apparatus | Relevant when the same switch family is used in trackside or station cabinets |
| EN 61373 / IEC 61373 | Shock and vibration testing in three axes, graded by mounting category | The category number the report covers, for example Category 1 Class B |
Why it is mandatory: it is written into the contract
EN 50155 is not enforced by a market regulator the way CE marking is enforced for the European Union. It is enforced by the contract. Rolling-stock builders and metro operators write the standard, the class, and sometimes the exact test clause into the technical specification, and a bid that cannot produce the corresponding report is marked non-compliant regardless of price. That is also why this keyword attracts serious buyers: the enquiry that arrives through it usually already has a specification attached to it.
The one question that separates serious suppliers
Ask for the report, not the logo. A supplier who says a switch “has EN 50155” is making a claim. A supplier who sends a type test report naming the OT class, the ST class and the EN 61373 category is making a statement you can put in a tender file.
The same discipline applies to the certifications that surround rail equipment. CE is a manufacturer’s declaration of conformity rather than a third-party certificate. An ISO 9001, ISO 14001 or ISO 45001 certificate tells you about the factory’s management system, not about whether this unit survives this mounting position. None of them substitutes for the type test report of the product itself. Buyers who understand that distinction are the buyers worth having a technical conversation with.
The three specifications that decide the project, once the label is checked
Compliance is a threshold, not a ranking. Two switches can both be compliant and still differ enormously in whether they suit your installation. Three specifications do most of the deciding.
Vibration and shock: state the EN 61373 category
EN 61373 classifies equipment by where it is bolted, and severity rises steeply as you move from the vehicle body towards the wheelset.
| EN 61373 category | Mounting position | Typical equipment |
|---|---|---|
| Category 1, Class A | Vehicle body, general mounting | Passenger information displays, CCTV cameras, passenger Wi-Fi |
| Category 1, Class B | Vehicle body, direct structure mount | Train control and network cabinets – the usual case for a rail switch |
| Category 2 | Bogie frame | Speed sensors, bogie control units |
| Category 3 | Axle and wheelset | Axle-mounted encoders |
Testing runs in three phases: functional vibration while the equipment is operating, endurance vibration over a long exposure, and shock simulating buffer impacts and emergency braking. A switch qualified for a trackside cabinet has not been tested for the train body, and a Category 1 Class A part has not been tested for a direct structure mount. Ask which category the report covers, and match it to the drawing.
Wide-range DC input: the 110 V bus is not a 110 V bus
The onboard DC bus is fed from the auxiliary converter and rises and falls with traction load. The standard sets the continuous range at 0.7 to 1.25 times nominal, with a temporary excursion to 0.6 and 1.4 times. On a nominal 110 V DC system that is a working window from 77 V to 137.5 V, and a transient range from 66 V to 154 V.
This is the most common mismatch in a rail bill of materials: a perfectly serviceable industrial switch, chosen for its temperature range, wired to a train battery and then resetting on every brake application. It is also the reason a rail switch datasheet leads with a voltage window rather than a single nominal figure, and the reason the DC input deserves the same attention as the temperature class.
Winsure’s rail transit switch family takes a DC 10 – 58 V wide-voltage input with dual-supply redundancy and reverse-polarity protection, and an AC 100 – 240 V variant is available for AC-fed station and trackside cabinets. That covers the 24 V, 36 V and 48 V nominal rolling-stock buses directly. Where a project runs a 110 V DC nominal bus, tell us the nominal voltage and we will confirm the input variant in writing against the 66 – 154 V window rather than leaving it to a datasheet footnote.
Fast start-up and hold-up: the ST and S classes
A rail switch has to start reliably after a cold soak, and it must not reboot when the supply blinks.
· ST classes define the switch-on extended operating temperature. The equipment must be capable of starting and reaching full operation after being exposed to the low end of its class on the platform in winter.
· S classes define ride-through: S2 covers a 10 ms interruption and S3 a 20 ms interruption, with no reset and no loss of stored configuration.
· Design consequences: conformal coating on the boards, no reliance on electrolytic capacitors that dry out under vibration, and firmware that keeps its configuration in non-volatile memory.
In practice the interruption class is what stops a camera stream dropping when the train takes power, and it is the specification most often missing from a first quotation, because it costs money and it is easy to leave out.
And the connector: why M12 rather than RJ45
RJ45 is an office connector. On a vehicle it loses contact under sustained vibration, and the plastic latch is a service liability in a carriage that is cleaned aggressively. EN 50155 equipment for the access layer therefore uses threaded M12 connectors – X-coded for Gigabit Ethernet, D-coded for Fast Ethernet – with IP67 sealing and a mating life measured in thousands of cycles rather than hundreds. Torque matters as much as the connector: an under-torqued M12 coupling does not fail immediately, it shows up months later as an intermittent link that nobody can reproduce.
Reference topology for a metro, tram or light-rail line
A metro communication network is three layers with three different jobs. The onboard layer moves data inside the train and hands it to the train-to-ground link. The trackside layer carries it along the line and has to survive the environment. The station and control layer records, displays and alarms on it. The reference design below is the one Winsure publishes for its railway transit communication solution.
Figure 2 – Reference topology: carriage access layer with M12 rail switches, a dual-redundant trackside ring, and the station and control centre. What each layer has to carry is different.
Layer 1 – onboard access
One switch per carriage is the usual starting point, plus one in the cab or on the locomotive for the train-level devices. Each carriage switch aggregates that carriage’s equipment: the passenger information displays and the coach controller, the CCTV camera or video encoder, the IP telephone, and the Wi-Fi access point. Between carriages the link runs on fiber rather than copper, which removes the earth-potential problem that appears when two vehicles are coupled and separated all day.
PoE is optional on this layer and worth having if a carriage carries cameras or access points. If you take it, remember that the PoE budget has to hold up across the same supply window as the switch itself, so a brownout budget is part of the PoE calculation and not a separate topic.
Layer 2 – train-to-ground and the trackside ring
Where the line has a trackside network, the usual design is a small number of switches in a ring rather than a star. On a metro the data path runs along the tunnel or the viaduct inside the same cable route as everything else, so a single cut is a normal event rather than an exceptional one. A ring with deterministic recovery is worth more than a faster switch: when a cable is cut during track work, the difference between a 20 ms recovery and a 200 ms recovery is whether the CCTV stream and the passenger information update survive, or restart.
The same switch family can serve trackside cabinets as well as the train, which is where the EN 50121-4 part of the family applies. Specifying one equipment family across both environments reduces the spares holding and simplifies maintenance qualifications, but only if the environmental class of each location is stated on the drawing.
Layer 3 – station and control centre
The station equipment room holds the aggregation switch, the video recording and archive, and the optical distribution frame where the single-mode backbone is terminated. These rooms are climate-controlled, so the constraint here is capacity and management rather than temperature: port count, uplink headroom, and a management interface the operator’s team already knows.
Keep the control centre out of the switching path of the onboard ring. The train’s own network should recover without waiting for a station device to converge, and the recording system should be a consumer of the video stream rather than a participant in its delivery.
PIS and CCTV backhaul: two different traffic profiles
The two largest traffic sources onboard a metro train look similar on a diagram and behave nothing alike.
| Traffic | What it actually needs | What to specify |
|---|---|---|
| Passenger information (PIS) | Small, steady packets to many displays. Availability and multicast efficiency matter far more than bandwidth | Ring recovery time, IGMP snooping for multicast, and a switch that restores service without operator action |
| CCTV backhaul | Sustained upstream video from encoders to the recorder. The heaviest load on the consist | Uplink capacity and per-port priority, so video is not starved by peak PIS traffic |
| Telephony and Wi-Fi | Bursty per-passenger traffic to PoE-powered endpoints | A stated PoE budget per port and per switch, with port priority so a supply dip sheds the least critical load first |
| Train control and signalling | Governed by its own functional-safety standards | Kept on a separate network. Passenger services traffic should not share it |
Note the last row carefully. A passenger information and CCTV network is a communications network; train control and signalling is a safety system with its own standards, its own segregation rules and its own acceptance process. Sharing a physical switch between them is a design decision for the signalling authority, not a cost optimisation, and it is better to say so early than to be told in a design review.
Winsure rail transit switches, and how to verify an EN 50155 claim
The rail transit switch family
Winsure builds its rail transit switches on a threaded M12 interface. The 8-port model is designated wsCom3010-8GM12/DC, and the M12 rail series appears in the Winsure railway transit solution as the carriage switch shared with the passenger information system. Two variants are offered: a rugged unmanaged unit for vehicle and trackside use, and a managed Layer 3 unit for the carriage aggregation role. Both are specified in the Winsure product manual to comply with EN 50155 and EN 50121 industry standard requirements.
| Specification | Rugged unmanaged (vehicle and trackside) | Managed Layer 3 (carriage aggregation) |
|---|---|---|
| Ethernet ports | 8 x Gigabit, M12 X-coded | 8 x 10/100/1000 M12, plus 1 x Console RJ45 / USB management port |
| PoE | Not offered on this variant | Optional, IEEE 802.3af/at PSE, up to 30 W per port at 48 V DC |
| Management | Unmanaged | STP / RSTP / MSTP, IGMP / MVR, Q-in-Q, LLDP, DHCP, port mirroring, storm control, link aggregation up to 8 groups, ACL, QoS, 802.1x, DoS protection, SNMP v1/v2/v3, RADIUS / TACACS+, IPv4 / IPv6 |
| Power input | DC 12 – 52 V (non-PoE), M12 4-pin A-coded power connector, overload and reverse-polarity protection | DC 10 – 58 V wide voltage with dual-supply redundancy and reverse-polarity protection; built-in 4.0 A overcurrent protection; AC 100 – 240 V variant available |
| Operating temperature | -40 ~ +85 °C; storage -40 ~ +85 °C | -40 ~ +85 °C; storage and transport -40 ~ +95 °C |
| Surge and ESD | EMC per FCC Part 15 and CISPR 22 Class A; ESD IEC 61000-4-2 Level 4; surge IEC 61000-4-5 Level 4; magnetic field IEC 61000-4-8 Level 5 | Power port IEC 61000-4-5 Level 3 (4 kV / 2 kV); Ethernet port IEC 61000-4-5 Level 3 (6 kV / 2 kV); ESD IEC 61000-4-2 Level 4 (15 kV); lightning protection 4 kV / 6 kV; EMI Class A |
| Mechanical testing | Shock IEC 60068-2-27, vibration IEC 60068-2-6, free fall IEC 60068-2-32 | Free fall 0.5 m; enclosure and mounting as below |
| Enclosure and mounting | Metal enclosure, natural convection, fanless, wall-mountable | IP40 metal enclosure, fanless aluminium heat dissipation, 1U rack-mount |
| Dimensions and weight | 157.8 x 121 x 43.2 mm, 0.65 kg | 485 x 250 x 45 mm, 2.8 kg |
| Switching capacity | 20 Gbps backplane, 2 Mbit buffer, latency under 10 µs, 8K MAC table | 30 Gbps backplane, 16 Mbit buffer, latency under 10 µs, 8K MAC table |
| MTBF | 300,000 hours | 100,000 hours |
| Certification and warranty | CE, FCC, RoHS, ISO 9001; MIIT network access licence and Ministry of Public Security inspection report; 5-year warranty | 5-year warranty; EN 50155 and EN 50121 compliance as stated in the product manual |
Both variants are fanless, which matters more on a train than in a factory: a fan is a wearing part, it ingests brake dust, and it is the component most likely to be the reason a carriage is taken out of service. Both also use a wide-voltage DC input, which is what makes the same hardware usable on a 24 V or 48 V bus.
How to verify an EN 50155 claim, in six documents
When you are comparing suppliers, ask for these six things. A supplier who can produce all six is a supplier you can put into a tender file.
| # | Document or figure to ask for | Why it matters |
|---|---|---|
| 1 | The type test report, with the declared OT and ST classes | A temperature range on a brochure is not a class. The report states which class was actually tested. |
| 2 | The EN 61373 category the report covers | Category 1 Class A and Category 3 are different products. Match the category to the mounting drawing. |
| 3 | The supply voltage range tested, expressed in absolute volts | Compare it with your nominal bus window – 66 to 154 V for a 110 V DC system – rather than with a marketing phrase. |
| 4 | The supply interruption class (S2 or S3) and the hold-up time | This is what determines whether the link survives a traction transient, and it is the figure most often omitted. |
| 5 | EMC test data to the EN 50121 series | General industrial EMC data does not answer the rolling-stock question. |
| 6 | Insulation and fire performance (EN 50124-1, and EN 45545-2 where the vehicle specification calls for it) | Required in most vehicle specifications, and routinely missing from a first quotation. |
If a supplier cannot name the classes, the answer is not “we comply” – it is that the test data has not been published. That makes the question a useful filter, because the projects that ask all six are the ones with a budget and a delivery date.
Where this equipment is already in service
Winsure’s rail transit switches sit inside a broader industrial networking range that is in service on utility, industrial and transport projects, and the group’s project record includes the Zhengzhou urban rail transit Line 3 Phase I PPP project alongside power, metallurgy and manufacturing references. Project experience is not the same thing as a type test report and should not be presented as one – but it does tell you the equipment has been through a real acceptance process rather than only a laboratory.
For buyers who want the wider picture of how the same switches are used across industries, the industry solutions index collects the manufacturing, power and utility references together, and the full range is listed under products.
Getting to a specification answer
Send us four things and the technical conversation becomes short: the nominal bus voltage of the vehicle, the mounting position of the switch in the consist, the OT class your specification calls for, and the number of devices per carriage. We will come back with the model, the input variant, and the test documentation that matches.
OEM and ODM requirements are supported, including connector and labelling changes for a specific rolling-stock programme. Where a project calls for a class or a mounting category outside the standard variants, tell us and we will confirm in writing rather than quote the nearest product that happens to be in stock. Written quotations are issued within 24 hours, and the range is summarised on the managed industrial switch and industrial grade switch category pages, with the wider range on the switches index. For the associated cabling and termination, see fiber optic cables, single-mode fiber patch cords, optical distribution frames and the transceiver range. For comparable industrial designs in the same family, the wsCom3028G-4GSFP-8G/DC-INT, the wsCom3010G-2GSFP-8G/DC-INT and the wsCom3010LG-2GSFP-8G/DC-INT show what the wider industrial managed range covers.
Winsure Communication is a Shenzhen-based industrial communication manufacturer, founded in 2016 within the Hansun group, with a factory under ISO 9001, ISO 14001 and ISO 45001 management systems. You can find the background on the about us page and reach the technical team through contact us – info@cnwinsure.com.
Frequently asked questions
1.Is EN 50155 a certification?
No. EN 50155 is a standard, and no notified body issues an “EN 50155 certificate”. A manufacturer declares compliance, and the evidence is a type test report from an accredited laboratory that states which temperature class, which EN 61373 category and which supply conditions were tested. Ask for that report by name and read the declared classes.
2.Can I use a rugged industrial switch on a train instead?
Usually not. A rugged industrial switch is qualified for a wide temperature range and for general industrial EMC, but the train bus is a different electrical environment and the vehicle body is a different mechanical one. The practical failure is usually the power input: a DC 12 – 55 V input sits below the continuous working window of a 110 V DC nominal system, which is 77 to 137.5 V. The connector is the second failure: RJ45 does not survive sustained vibration the way a threaded M12 coupling does.
3.What is the difference between EN 50155 and EN 50121?
EN 50155 is about the equipment: temperature, supply, interruptions, insulation, testing and documentation. EN 50121 is about electromagnetic compatibility in the railway environment, split by location – EN 50121-3-2 covers rolling stock, EN 50121-4 covers signalling and trackside apparatus, and EN 50121-5 covers fixed power installations. A rail switch datasheet will normally reference both.
4.Which M12 coding do I need for Gigabit Ethernet?
X-coded. M12 X-coded is the four-pair coding used for Gigabit Ethernet and provides IP67 sealing with a threaded coupling. D-coded is the two-pair coding used for Fast Ethernet, and A-coded is normally reserved for power and for low-speed signals. Because the access layer may carry both cameras and displays, confirm the coding of every port rather than assuming a single code across the switch.
5.What temperature class should a carriage network switch declare?
The class follows the mounting position and the operator’s specification, and it is normally expressed as an OT class rather than as a bare range. Cabinets inside the vehicle body in a temperate climate are frequently specified at OT3 or OT4, while equipment in an unheated area or in a vehicle operating in a cold climate moves towards the wider classes. The related ST class covers start-up after a cold soak, which is why a switch that operates at a low temperature is not automatically a switch that starts at it.
6.Does EN 50155 apply to trackside cabinets?
Not in the same way. EN 50155 is written for equipment on rolling stock. Trackside and station equipment is governed by the trackside parts of the same standard family, and the EMC requirement in particular moves to EN 50121-4. If the same switch family is used in both locations – which is a sensible spares strategy – state the environmental class of each location separately on the drawing rather than assuming one specification covers both.