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Electric Machines
Published in Iqbal Husain, Electric and Hybrid Vehicles, 2021
An electric machine is an electromechanical device used for energy conversion from electrical to mechanical and vice versa. In a vehicle system, the electric machine can be designed to process supplied energy and deliver power or torque to the transaxle for propulsion. The machine also processes the power flow in the reverse direction during regeneration when the vehicle is braking converting mechanical energy from the kinematics into electrical energy. The term ‘motor’ is used for the electric machine when energy is converted from electrical to mechanical and the term ‘generator’ is used when power flow is in the opposite direction with the machine converting mechanical energy into electrical energy. The braking mode in electric machines is referred to as regenerative braking. There are electrical, mechanical and magnetic losses during the energy conversion process in either direction in an electric machine, which affect the conversion efficiency. Some energy is always lost from the system for any energy conversion process. However, the conversion efficiency of electric machines is typically quite high compared to that of other types of energy conversion devices.
D.c. Machines
Published in John Bird, Newnes Engineering Science Pocket Book, 2012
The efficiency of an electrical machine is the ratio of the output power to the input power and is usually expressed as a percentage. The Greek letter, η (eta) is used to signify efficiency and since the units are powerpower, then efficiency has no units. Thus efficiency,η=(outputpowerinputpower)×100%
D.c. machines
Published in John Bird, Electrical and Electronic Principles and Technology, 2017
The efficiency of an electrical machine is the ratio of the output power to the input power and is usually expressed as a percentage. The Greek letter, ‘η’ (eta) is used to signify efficiency and since the units are power/power, then efficiency has no units. Thus efficiency,η=(outputpowerinputpower)×100%
The effect of gamma radiation on the stator insulation of rotating electrical machines
Published in Radiation Effects and Defects in Solids, 2019
Nenad Kartalović, Bojan Jokanović, Milan Bebić, Đorđe Lazarević
Production, transmission and consumption of electricity is largely carried out by electrical machines. The construction of electrical machines is simple, easy to maintain and has a high level of reliability (if they are designed taking into account all relevant parameters). When designing electrical machines, it is necessary to optimize the relationship between the greater load of active material and lifetime (the duration of reliable exploitation). Electrical machines are divided into static (transformers) and dynamic (rotating machines, i.e. motors). According to data from engineering practice about 50% out of the functions of electrical rotating machines are the consequence of the weakening of the insulation characteristics of the stator windings. This procedure depends on the constructive solutions, the applied materials and the conditions of exploitation (1–5).