The connection of the electric motors to a public power grid must comply with the requirements for this purpose, which are established by standard. Generally, we try to start a motor at full voltage in order to make the most of the starting torque. When starting the full voltage of an engine causes a voltage drop greater than the maximum permissible, we must resort to a starting device with reduced voltage, but care must be taken to see if the torque is sufficient to drive the load. https://www.mrosupply.com/v-belts/v-belts/a-section/178194_a70_gates-rubber/
There are currently two methods of reducing starting voltage: In supplying less than normal voltage current by means of resistors, inductors or autotransformer, all low voltage starting systems have the advantage of reducing current, the disadvantage that the starting torque or torque is reduced in proportion to the square of the voltage reduction supplied to the motor or to provide correct current at the normal voltage causing the motor to be temporarily connected to the grid with the winding for a higher voltage , using the star-triangle starting system.