Product description 3.2 Basic physical principles of a three-phase induction motor Starting current Three-phase induction motors have a high direct starting current I starting . Depending on the motor type, this current can be between three and fifteen times as high as the rated operational current. Seven or eight times the motor's rated current can be assumed as a typical value. Disadvantage This results in the following disadvantage: • Higher load on the electrical supply system. The supply system must therefore be dimensioned for this higher power during the motor startup.
0RWRUFXUUHQW , , 'LUHFW RQOLQH VWDUWLQJ , 1RP 0RWRUVSHHG Q Q 1RP Figure 3-1 Typical starting current characteristic of a three-phase induction motor Starting torque The starting torque and the breakdown torque can usually be assumed to be between two and four times the rated torque. From the point of view of the load machine, this means that the starting and acceleration forces exert a higher mechanical load on the machine and the product being conveyed compared to nominal operation. SIRIUS 3RW30 / 3RW40 16 Manual, 01/2010, 535 1995-02 DS01 P