UIC 550: Power Supply Installations for Passenger Stock (RIC Voltages) – 2026 Guide

Detailed guide to UIC 550 (2026). Understanding the 4 standard RIC voltages (1000V, 1500V, 3000V), the High Voltage Train Line, and how multi-voltage converters enable international rail travel.

UIC 550: Power Supply Installations for Passenger Stock (RIC Voltages) – 2026 Guide
September 26, 2023 4:39 pm
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💡 Key Takeaways: UIC Leaflet 550

  • Core Function: Defines the electrical systems required for passenger coaches to operate internationally across different power grids.
  • The “Big 4” Voltages: Standardizes the four acceptable input voltages from the locomotive: 1000V AC, 1500V AC, 1500V DC, and 3000V DC.
  • RIC Regime: Ensures a coach marked with “RIC” can accept power from any compliant locomotive in Europe without blowing a fuse.
  • Shore Supply: Specifies the connectors and safety protocols for plugging trains into the grid (Pre-conditioning) at depots.
⚡ 2026 Energy Update: Modern rolling stock creates heavy demands on the UIC 550 “Train Line” due to powerful HVAC systems and passenger WiFi/Charging points. The 2026 focus is on Smart Energy Management—using AI to load-shed non-essential systems (like dimming lights) when the locomotive needs peak traction power.

When you cross a border in Europe on a train, the locomotive might change, or the voltage in the overhead wires might change. But the lights in your cabin stay on, and the AC keeps running. This seamless experience is made possible by UIC Leaflet 550.

This standard defines how power is transmitted from the locomotive (the source) to the passenger coaches (the load) via the Train Line (also known as the Heating Line or Train Busbar).

The Challenge: 4 Voltages, 1 Train

Europe does not have a single railway voltage. To ensure Interoperability, UIC 550 dictates that international passenger coaches (RIC vehicles) must be equipped with a Static Converter capable of accepting all four standard voltages:

Voltage TypeNominal ValuePrimary Users (Regions)
AC (Low Freq)1000 V $\sim$ 16.7 HzGermany (DB), Austria (ÖBB), Switzerland (SBB), Sweden, Norway.
AC (Standard Freq)1500 V $\sim$ 50 HzAlso used where the overhead line is 25kV 50Hz (via transformer step-down).
DC (Medium)1500 V DCFrance (SNCF – Conventional), Netherlands (NS).
DC (High)3000 V DCItaly (FS), Belgium (SNCB), Poland (PKP), Spain (Renfe).

How It Works: The “Train Line”

The Train Line is a single-pole high-voltage cable running the length of the train. The return current flows through the wheels and the rails.

  • The Selector: Modern coaches have an automatic voltage selector. It detects whether the incoming power is AC or DC, and what voltage level it is.
  • The Converter: This device takes the “dirty” variable input (1000V-3000V) and converts it into a stable onboard supply (typically 24V DC for batteries/control and 400V AC 3-phase for HVAC motors).

Shore Supply (Depot Power)

Trains often sit in depots overnight. To keep them warm (or cool) without running a locomotive, they are plugged into a Shore Supply. UIC 550 standardizes these external plugs to ensure a German depot can power a visiting French train safely.

FAQ: Passenger Power Supply

Can I plug a standard device into the UIC 550 Train Line?

Absolutely not. The Train Line carries lethal High Voltage (up to 3000V DC). The sockets you see at your seat (230V) are fed from a separate, isolated auxiliary circuit powered by the onboard converter, not directly from the train line.

What does the “RIC” marking mean on a coach?

RIC stands for Regolamento Internazionale Carrozze. A coach with this marking complies with UIC 550 (and other standards), certifying it can travel freely across most European borders and accept all 4 standard power voltages.

Why do the lights flicker when the train passes a neutral section?

When passing a “Phase Break” or neutral section (where the power source changes), the main circuit breaker opens (VCB Open). The UIC 550 line loses power for a few seconds. Modern trains use batteries to keep LEDs on, but older stock may flicker as the converter restarts.

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