The Results of Studies of the Modes of Operation Asynchronous Motors at Lower Voltages to Determine Opportunities to Increase Their Energy Indicators

Abstract

Energy performance asynchronous motors (AD), power factor and efficiency, significantly depend on the parameters of the supply voltage (magnitude, frequency) and mode of operation (load factor). To improve the efficiency of operation, various methods of reducing reactive power are used. It is possible to distinguish artificial methods based on the use of additional devices, and the possibility of reducing reactive power in a natural way. The research is aimed at identifying the dependence of the energy parameters of the AD in the function of the stator voltage. A characteristic operational feature of three-phase AD is relatively large values of idling currents I 0 (up to 40% of I n), which are more reactive and largely determine the power coefficients. Thus, reactive power consumed from the network is less dependent on loads. When the phase voltage changes, the reactive power changes in the quadratic dependence. In addition, the change in voltage leads to a change in the inductive resistance, depending on the saturation of the magnetic system of AD. In determining the feasibility of changing (reducing) the phase voltage to the AD, investigated the dependence of the additional reactive power dQ, which is the greater, the less loaded AD, and the loss of active power in the AD, determining their heating, in the function U f .. The performed studies reveal the possibility of natural increase of the co-efficiency of AD power when working with the load factor K Z <1. In the case of the implementation of these opportunities, the weighted average power factor of the cosφ ср of production enterprises as a whole may not be less than 0.9. The results of the research allow us to conclude about the feasibility of using low voltage U s for three-phase motors operating in areas of low loads.