Ocena oszczędności energii elektrycznej przy skokowej regulacji napięcia w silniku asynchronicznym klatkowym

In order to enhance energy indices and obtain electrical energy savings for an asynchronous squirrel-cage motor operating on a long-time basis at a load lower than the rated load it needs to reduce its supply voltage. Efficient operation obtained that way can apply to a single motor or a set of motors driving the same machines. Motor load can vary within a wide range depending on the operation kind. Particularly disadvantageous is operation at little load or at idling, when energy indices of the motor are very low. In such a case it is necessary to apply voltage that can be varied depending on the load factor. When voltage is changed simultaneously with a load change the motor runs at higher values of the indices that decide over electrical energy consumption. At the rated load a motor should be supplied with rated voltage and when the load gets reduced the supply voltage should also be adequately decreased. The lowest voltage is required at the idle run. Relative value of the voltage is then of ca 0.3. Voltage reduction brings about a decrease of voltage-dependent energy losses and an increase of efficiency and the power factor, which leads to the power input reduction and consequently to electrical energy savings. The paper presents motor operation conditions that should be met at a sudden voltage change and rules for enhancing energy indices on the basis of algorithms that maintain such parameters as: minimal current, maximal power factor and maximum efficiency at a preset level. Additionally, runs of the basic motor quantities such as: current input, power factor, efficiency, and slip at step-regulated supply voltage have been determined