Optimization of diesel engine - synchronous alternator group

The paper describes the findings of an experiment that is a result of close collaboration among four companies. The paper discusses the experiment on one locomotive by using a microprocessor-based relay, multiple function relay (MFR) SEL-701, for on-line measurement, control and optimization of a HEP (head end power) group. The HEP has a diesel engine, 810 HP/908 HP, 1800 rpm, and a double wound three-phase self-excited synchronous alternator, 625 kVA, 575 V. The HEP group is installed on the locomotive and supplies the electrical hotel power to the train´s coaches. The relay SEL-701 (Schweitzer engineering laboratories) measures the diesel engine temperatures on 7 different points and the winding temperatures at 3 internal points, one per each phase. The SEL-701 monitors alternator output currents, voltages and controls one (or both) train lines when the diesel engine´s hottest temperature equals the maximum admissible temperature. Amongst others the paper highlights the benefits derived by use of on-line measurements of the diesel engine before and after relocation of a pre-existent engine shutdown temperature probe. In addition, the paper discusses the decrease in the numbers of diesel engine shut downs due to the modified mode of protection and the increase in available electrical power supplied to the train lines together with the comparison of the HEP group efficiency before and after modification.