📝 How it works:
Rated and starting current of a three-phase motor, comparing direct-on-line with star-delta (current and torque to one third).
Fill in the fields below and click "Calculate".
Rated and starting current of a three-phase motor, comparing direct-on-line with star-delta (current and torque to one third).
Fill in the fields below and click "Calculate".
The rated current follows from In = P / (√3 · U · cos φ · η). The direct-on-line (DOL) starting current is 6–8 times the rated current. Star-delta starting reduces both the starting current and the starting torque to one third of DOL.
Therefore star-delta suits only drives with a low load torque at start (e.g. fans, unloaded pumps). The actual values (Ia/In, cos φ, η) are on the motor nameplate.
Advertisement
