DC-machines

Gullapalli D, Phillips LH, II (2004). Neurosarcoidosis. Current Neurology and Neuroscience Reports 4 441-447 Hankey GJ (1991). Isolated angiitis/angiopathy of the central nervous system. Cerebrovascular Diseases 1 2-15 Harrison CN, Linch DC, Machin SJ (1998). Desirability and problems of early diagnosis of essential thrombocythemia. Lancet 351 846-847... 

In separately excited DC machines (Fig. 5.3d) the excitation is obtained by means of field windings which have a supply separated from the rotor windings, and this gives a separated control of speed and torque, according to what is required in an electric vehicle. Separately excited brushed DC motors were widely... 

Fig. 5.3 Different methods of supplying current to the excitation windings for brushed DC motor, a parallel DC machines, b series DC machines, c compound DC machines, d separately excited DC machines...

DC machines are simpler and cheaper, because their speed regulation is based on scalar controls. For that reason they need simple electronic boards to control the DC electric drive operations. Moreover, they have the advantage that they can be fed by the DC supply already on board. On the other hand, the principal disadvantage is represented by the maintenance required, since for instance brushes need to be periodically checked and changed. Another point to take in consideration is that fuel cell electric vehicles equipped with brushed electric machines would require specific safety devices to avoid that sparks of the collector during the commutation might interact with the hydrogen used as fuel on board. 

General Requirements for all Machinery OSHA 1910.212 Occupational Safety and Health Administration, Washington, DC Mechanical Power Presses OSHA 1910.217 Occupational Safety and Health Administration, Washington, DC Machine Tools—Manufacturing Systems/Cells—Safety Requirements for Construction, Care, and Use ANSI B 11.12, American National Standards Institute, New York, NY... 

In recent years, the electrical drive manufacturers who have traditionally supplied equipment for mine winders have ceased production of large, slow speed DC machines and, depending on the manufacturer, only slow speed synchronous or induction machines suitable for mine winders can be sourced in sizes exceeding ISOOkW. (See Figure 27.)... 

Section 8.2.1 immediately following this short introduction presents more models of DC-machines while Section 8.2.2 deals with AC synchronous and induction machines, the latter being discussed in more detail. Both are the kind of machines most likely to be encountered in industrial systems converting power in the range... 

DC-Machines Brushed DC-Motors Separately, Parallel, Series, and Compound Excited DC-Motors... 

Institute of Medicine of the National Academies (2007) The future of drug safety promoting and protecting the health of the public. The National Academies Press, Washington, DC Machin D, Campbell MJ (2005) Design of studies for medical research. John WUey Sons,... 

Sen, P. C. Principles of Electric Machines and Porver Electronics. 2d ed. New York John Wiley Sons, 1997. An advanced textbook providing a thorough treatment of electromagnetic machine principles, including magnetic circuits, transformers, DC machines, and synchronous and asynchronous motors. 

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