Technical

Electric Diesel
                             Hauling

Sequence from the previous issue

The three-phased alternative power machine has given the possibility that the railway men dream, the electrical hauling engine without maintenance, to become true.
The electrical hauling with three-phased asynchronic engines with the rotor in short-circuit had the so-called start off in the '90s, presently being in operation, in working process or in the stage of orders for thousands of pieces of locomotives and motorcars. The electrical Diesel hauling has closely followed the electrical hauling and presently we can talk about final technical solutions in this field, respectively the electrical transmission c.a. - c.a. Due to the operation at high voltage (of three-four times higher than the transmission c.a. - c.c.), the c.a - c.a. transmission allowed the reduction of the dimensions of the main generator. The unlimited possibilities of the power converter to transform the static parameters of the electrical power supplied by the generator allowed the annulment of the other auxiliary generators from the locomotive with c.a. - c.c. transmission (two-four as number).
The electrical Diesel locomotives with c.a. - c.a. transmission, although they are extremely sophisticated, have reasonable prices and deserve the effort to be purchased. They take advantage, besides the newest achievements in the electronics field, of a higher power and of the latest news in the thermal engines - namely, the fast Diesel engine with commonrail injection electronically driven, with reduced consumptions of fuel in comparison with the slow and semi-rapid engines, but with a perfectly comparable life duration.
Presently, an electrical Diesel locomotive with c.a. - c.a. transmission is superior to the c.a. - c.c. solution through:
- superior global efficiency and, consequently, corresponding reduces energetic consumptions;
- the reduction of the number of generators ( 1, in comparison with 4);
- the reduction of the power for the auxiliary services;
- the supply of the passengers trains with the electrical power in all the field voltage and frequencies;
- retrieving electrical braking;
- extremely reduced costs for the maintenance of the electrical equipment;
- reduced weight;
- the possibility to achieve universal locomotives ( for the freight train transport, as well as for passengers);
- the reduced aggressiveness against the track;
- the increased maximal traffic speed (of 200 km/h and even more ), with the possibility to regulate it, according to the needs, without interfering on the hauling gearing .
Also taking advantage of the modern mechanics, taken over from the electrical locomotives, the achievements in the field are presently characterized by the following parameters:
- The locomotive on six axles of 5,000 - 6,000 HP, the weight of 180 - 190 t, using semi-rapid Diesel engines - for freight transport services;
- The locomotive on four axles of 3,000 - 3,500 HP, weight of 84 t, with the fast Diesel engines - for universal use.
The calculations regarding the hauling capacity have been confirmed on the occasion of the tests that have been performed, also in Romania. The electro-mechanical feature of the three - phased asynchorinc hauling with the rotor in short-circuit, doubled by the electronic means of surveillance of their operation, as well as of the entire locomotive (with fast reaction), allowed the hauling of the heavy trains in difficult ramps with a locomotive on four axles, instead of a locomotive on six axles.
The conclusion of those presented above with regard to the electrical Diesel hauling is that, currently, after the ascendant evolution of the electrical transmission, the technical solutions of c.a. - c.a. type have already grown up and reached to the generalized consecration. The purchase of these locomotives is justified through their universal feature, by reduced costs for maintenance and exploitation and by reduced energetic consumptions. Concretely, taking into consideration the existence and the pounding of the electrical hauling, the universal electrical Diesel locomotive with c.a. - c.a. transmission proves to be sufficient for the needs of the railway transport from Romania, including the perspective development, having the following main features:
- Diesel engine power - around 3,000 HP;
- Maximal speed - 140 - 160 km/h;
- The formula of the axles - Bo - Bo;
- Weight - 80 - 84 t;
- UIC construction with the provision of the compatibility with the European railway networks.
The current moment is favorable for the change of the electrical Diesel locomotives generation, to which the techniques of the '50s imposes the endowment of the new locomotives in order to meet the European standards.
The experience on world plan and from Romania regarding the "radical" modernization of the old locomotives proves extremely expensive, and the benefices are relative, because the old parties remained on the locomotive "pull back" and shadow the benefices brought by the new parts adopted within the modernization action. At this chapter, there has been empirically established the "barrier of the modernization cost: if the modernization costs 800,000 USD for a life duration of 12-15 years, it is more likely to buy a new locomotive for the next 40 years".
A new locomotive does not mean only a modern transmission c.a. - c.a., but also a modern metallic construction and a last generation suspension, fact that provides a superior running position and an increased comfort. And, besides these, efficient brakes, improved auxiliary equipment, ergonomic, according to the last international regulations: or, briefly, "a shop window with all the current technological news".

Daniel Secarescu