On line measurement and improvement of working parameters of a diesel engine-synchronous alternator group

The paper discusses an experiment on a locomotive 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, 810-908 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 microprocessor based relay, MFR SEL-701 (Schweitzer Engineering Laboratories) measures the diesel engine temperatures on seven different points and the winding temperatures at three internal points, one per phase. The SEL-701 monitors alternator output currents and voltages and controls one (or both) train lines when the diesel engine´s hottest temperature equals the maximum admissible temperature. Amongst other benefits, the paper highlights those derived by use of on line measurements of the diesel engine before and after the relocation of a preexistent engine shutdown temperature probe. In addition, the paper discusses the decrease in the number 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.