Calculation of starting resistances and acceleration relay settings for an asynchronous lifting motor

Abstract

The initial data for determining the starting resistance in the case under consideration are the following values. The power and type of lifting motor, for which, based on the corresponding catalogs, in turn, can be found: a) the ratio of the breaking (maximum) torque to the rated torque b) the rated rotor voltage Enom; c) rated rotor current In; d) engine efficiency; f) synchronous Ps and nominal Pnom number of revolutions of the latter. Calculated starting torque values. 3) Values of static moment of resistance corresponding to the starting period. 4) The number of stages (sections) of the rotor rheostat. 5) Starting period t1 and the full period of the working cycle T, including pause θ, in relation to a given tachogram. According to the given graphical method for determining starting resistances, it is necessary first of all to construct the mechanical characteristics of the engine: natural, corresponding to the own resistance of the rotor winding, and artificial, caused by the inclusion of certain stages (sections) of starting resistances in the rotor circuit. For this purpose, it is necessary to set the limiting (maximum and minimum) values of fluctuations in the starting torque, varying around its calculated value.