Thermal studies of D.C. traction motors

This paper describes a thorough thermal study on a fleet of DC traction motors which were found to suffer from overheating after 3 years of full operation. Overheating of these traction motors is attributed partly because of the higher than expected number of starts and stops between train terminals. Another probable cause of overheating is the design of the traction motor and/or its control strategy. According to the motor manufacturer, a current shunt is permanently connected across the motor field winding. Hence, some of the armature current is bypassed into the current shunt. The motor then runs above its rated speed in the field weakening mode. In this study, a finite difference model has been developed to simulate the temperature profile at different parts inside the traction motor. In order to validate the simulation result, an empty vehicle loaded with drums of water was also used to simulate the full pay-load of a light rail vehicle experimentally. The authors report that the simulation results agree reasonably well with experimental data, and it is likely that the armature of the traction motor will run cooler if its field shunt is disconnected at low speeds

Senator Elizabeth Warren fights the White House over the secret Trans-Pacific Partnership #TPP #TPPA

In his visit to the G20 in Brisbane, President Barack Obama sought to promote his ambitious Pacific Rim trade agreement — the Trans-Pacific Partnership (TPP). He told an audience at the University of Queensland: We’ll keep leading the effort to realize the Trans-Pacific Partnership to lower barriers, open markets, export goods, and create good jobs for our people. But with the 12 countries of the TPP making up nearly 40 percent of the global economy, this is also about something bigger. It is our chance to put in place new, high standards for trade in the 21st century that uphold our values. So, for example, we are pushing new standards in this trade agreement, requiring countries that participate to protect their workers better and to protect the environment better, and protect intellectual property that unleashes innovation, and baseline standards to ensure transparency and rule of law.