Introduction
2.1 Basic physical principles of the three-phase asynchronous motor and operating principle of the soft starter
3RW44 soft starters
Manual, 03/2017, NEB535219502000/RS-AB/008
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Disadvantage
This results in the following disadvantage:
●
Higher load on the electrical supply system. This means that the supply system must be
dimensioned for this higher output during the motor startup.
Figure 2-1
Typical starting current characteristic of a three-phase asynchronous motor
Locked-rotor torque
The starting torque and the breakdown torque can usually be assumed to be between two
and four times the rated torque. For the load machine this means that the starting and
acceleration forces in relation to rated operation give rise to a higher mechanical load on the
machine and the conveyed material.
