UIC 552 railway connectors

UIC 552 series

Single-pole aluminium UIC 552 connector with automatic cover for 185 mm² train line cable

In brief. The UIC 552 connector links, between vehicles, the train line that powers heating, air conditioning, lighting and battery charging. Single-pole, in aluminium with an automatic cover, it takes a 185 mm² cable, withstands 3,000 V DC, carries 800 A at −10 °C and reaches IP 56. We supply the original part or a Form-Fit-Function alternative, with a reply within 48 working hours.

Below: how a UIC 552 connection is made up, our specifications and what we need to quote.

Request a quote for a UIC 552 connector

What is a UIC 552 connector used for?

It carries power from the locomotive to the coaches on trains approved for international traffic. UIC leaflet 552 is titled "Electrical power supply for trains – standard technical characteristics of the train line". It applies to all rolling stock and traction units fitted with a train line and running in international traffic. It covers couplers and conductors. Its 10th edition dates from 2005; according to the Intertek Inform catalogue, it is still current.

How is a UIC 552 heating connection made up?

The train line is a single conductor running beneath the whole train; the current returns through the rails. DB InfraGO, the German infrastructure manager, points out that it is also called the "heating line", a legacy of its original function. Today it charges batteries and lights, heats and air-conditions the coaches. Hence the large cross-section and the single pole of the connector.

This line takes several voltages depending on the network. An article in the journal Elektrische Bahnen (W. Fischer, 1983) lists four systems for passenger coaches: 1,000 V at 16⅔ Hz, 1,500 V at 50 Hz, 1,500 V DC and 3,000 V DC. Our connector is rated for 3,000 V DC, the highest of the four.

From one coach to the next, the connection is built around four items, which we supply as a complete system:

Item	Role
Plug for 185 mm² cable	End of the inter-vehicle cable (coupler)
Branch box	Outlet of the underframe cable towards the coupler
Junction box with automatic cover	Receives the plug, cover with automatic locking
Stowage box	Holds the plug when the coupler is not in use

For its own range, TE Connectivity also offers an intermediate branch box, a safety lock and an optional self-disconnecting coiled cable.

What are the specifications of the UIC 552 connector?

We take as our baseline the values published by TE Connectivity for its UIC 552: 800 A, 3,000 V DC, IP 56, 500 h salt spray, −50 °C to +120 °C. The rest comes from our technical data sheet.

Category	Specification	Value
Electrical	Number of poles	1
	Contact	Ø 25 mm
	Operating voltage	3,000 V DC
	Rated current	800 A at −10 °C (value taken from UIC leaflet 552)
	Withstand voltage	> 15 kV
	Electrical shock withstand	> 30 kV
	Contact resistance	< 1 mΩ
	Insulation resistance	> 5,000 MΩ
Materials	Housing	Painted aluminium alloy
	Insert	Polyamide
	Contact	Silver-plated brass
Environmental	Operating temperature	−50 °C to +120 °C
	Salt spray	> 500 h
	Sealing	IP 56 to EN 60529
	Fluid resistance	Diesel, mineral oil, acids, bases, cutting fluids
	Fire and smoke	EN 45545-2
Mechanical	Durability	500 mating cycles
	Vibration	1 g from 7 to 10 Hz (NF F 60-002, severity 1)
	Shock	30 g, 18 ms, half-sine

The 800 A rating applies at −10 °C, the condition set by the standard: bear it in mind if your rolling stock runs in very hot weather.

Which standards and qualifications apply?

UIC leaflet 552 defines the interface. Fire behaviour falls under EN 45545-2, mandatory for every component fitted to a train.

Standard	Scope
UIC 552, 10th edition (2005)	Train line: characteristics, couplers, conductors, coupler locking
EN 45545-2	Fire protection: fire and smoke requirements for materials
EN 60529	Ingress protection rating (IP 56)
NF F 60-002	Vibration testing (French standard)

Your UIC 552 connector cannot be found: what do we do?

We first look for the original part in the dormant stock held across our network in Europe and Asia. The original connectors we come across most often are made by Schaltbau and ERA Contact. Failing that, we reverse-engineer a Form-Fit-Function alternative: same contact size, same envelope, same cover, so that it mates with the boxes already installed. On an 800 A connection, crimp quality and contact resistance matter as much as geometry.

To quote, send us:

the original part number and manufacturer, read from the part or the parts list;
a photo of the marking, the contact face and the cover;
a drawing or an extract from the parts list, if you have one;
the quantity and the rolling stock concerned (coach series, locomotive);
the exact item: plug, branch box, junction box, stowage box or complete system.

All you have is an engraved number? Run a search by part number.

Frequently asked questions about the UIC 552 connector

Why does the UIC 552 connector have only one pole?

Because the train line is a single conductor: the current returns to the locomotive through the rails. DB InfraGO describes this arrangement, with return through the track, for supplying coaches from a diesel locomotive. A single large contact is therefore enough, provided it can carry the current for the whole train.

Which cable should be used with a UIC 552 connector?

Our UIC 552 connector takes a 185 mm² cable, the cross-section to which TE Connectivity also ties its 800 A rating. UIC leaflet 552 devotes a chapter to conductors. For an alternative, give us the part number of the cable in service: the cable gland and the contact are sized on its outside diameter and its core.

Can the junction box be replaced on its own?

Yes. We quote each item separately, including the junction box with automatic cover. Send us the part number of the box and that of the plug that mates with it: the alternative must accept the plugs already in service on your other coaches.

Does a UIC 552 connector have to meet EN 45545-2?

Yes. EN 45545-2 sets the fire and smoke requirements for materials and applies to every component fitted to a train. According to STRMTG, the French technical authority for guided transport, it covers new rolling stock as well as added or modified equipment; the usual level is HL1 outside tunnels, HL2 in tunnels. The material certificate can be supplied on request: state the level required.