The first of 40 new Artic low-floor trams for Helsinki was inaugurated in the presence of the Finnish Minister of Traffic on 13 June. The electric drive system for the vehicles has been supplied by Voith Turbo — a specialist manufacturer of hydro-dynamic drive, coupling and braking systems for road, rail and industrial applications, as well as for ship propulsion systems.
The conditions of Helsinki’s rail network are characterised by below-zero temperatures (with permafrost), salty condensation and summer temperatures up to 30°C. These circumstances were taken into account when Helsinki City Transport called for tenders; they resulted in a rather demanding list of requirements, which were subsequently
met by the consortium Transtech and Voith with the Artic low-floor tram.
Despite a freely pivoting bogie with continuous axles, it was possible to achieve a low-floor configuration. A separate motor-gear unit with a continuous output of 65kW drives each of the eight axles of the 27.6m-long vehicle. The axles receive their power via two EmCon double traction inverters (pictured below). Wheels, axles, axle bearings, the drive-related vehicle control and the diagnostic system are also supplied by Voith.
Energy generated during braking is fed back into the overhead contact wire; if the overhead network is unable to take it, the energy is stored in heat exchangers and used for the heating system. Trams are an important means of public transport in Helsinki. On 11 lines and across a 118km network, 112 vehicles move 57 million passengers per year.