Authors: L. GUREVICH, Dr., Head of Division at State Technical University of Volgograd, V. FOKIN, Director General, Energoservice

Overhead catenary systems installed on high-speed lines possess a number of unique characteristics that ensure safe and smooth train operation. This includes the increased tension of a contact wire, messenger cables and connecting wires; thermal endurance and wear resistance; increased mechanical strength of contact wires and cables; minimal mass of all structural elements but not at the expense
of strength and durability; and reliable rust protection. To satisfy these stringent requirements, Ø 120-150mm2 low alloy copper or bronze contact wires are traditionally used. The contact wire shall have minimum sag, which is ensured by an overhead catenary system that uses closely spaced droppers to attach the messenger wire or catenary to the contact wire.

Innovative MK-series messenger wire

Russian engineers have created a wire that is ideally suited for batch production while offering high strength, slight temperature-related linear deformation, good rust resistance, electrical conductivity which is close to copper conductors, and enhanced aerodynamic properties. The wires have standard dimensions and are compatible with standard fittings. MK-series compact and plastically-deformed messenger wires may also be used as auxiliary messenger wires, electric connectors between contact wire and feeder line wires.

This copper catenary alloy-free wire solution is a breakthrough in that it offers high strength without the traditional drawbacks of alloy-based solutions.
Advantages include:
– reduced amplitude and strength of wire dancing;
– reduced risk of wire break;
– low stress in the event of snow and ice accumulation due to the smooth exterior shape;
– high-strength parameters which are close to the performance of bronze wires;
– high current-carrying capacity and electrical conductivity, and;
– enhanced aerodynamic parameters.

Russian Railways (RZD) and the Russian R&D Institute of Rail Transport (VNIIZhT) have conducted comprehensive tests of the MK compacted copper messenger wire, which demonstrated that pressed wires provide an enhanced cross-section utilisation ratio, reduced electric impedance in the traction network, improved load-carrying capacity and better thermal resistance. An extensive testing programme checked the factors which may affect the catenary wire in real life but at the possible extremes of performance. This included a thermal degradation check with heating to 155°С, track resistance tests, bending tests, low-temperature creeping tests, endurance to
vertical oscillations (eolian vibration) with multiple heating to 100°С, and other tests, some of which have never been performed for catenary wires before.

As part of RZD’s Resource-Saving Technologies Deployment Programme, the MK-120 series compacted wire was installed as pilot messenger wire in 2015 and 2016 on track sections totalling 60km on the West Siberian Railway and South Urals Railway. The МК-120 wires were installed according to a traditional installation process using existing fittings and tools and the tests showed that the wire’s catenary impedance reduction would offer an economic benefit to the railway.

Following a meeting of the Innovative Technologies Working Group of the Russian Ministry of Transport in September 2016, it was recommended that state-owned companies purchase MK-series messenger wires. In 2017, the MK-120 compacted wires were installed on sections of the Sverdlovsk Railway, South Urals Railway and West Siberian Railway for a total length of 109.4km.

Full text can be found here http://energoservise.co...