10. Starting methods
Grundfos pumps and motors which carry the designation 3 x 380 - 415 V ∆ but NOT 690 V Y can also be started by means of star-delta starters, while the real voltage to the motor never exceed 400 V. Starting torque and current are considerably lower at star-delta starting than at direct-on-line starting: one third of the equivalent DOL value. Mismatching of motor torque speed curve and load torque speed curve. In the example shown here, the motor would slowly accelerate up to approximately 50 per cent rated speed.
% Full-load torque
Star-delta starting
d
oa
l mp
Pu
Moto
r
% Synchronous speed Mismatching of motor torque speed curve and the load torque speed curve. In this example, the motor would slowly accelerate up to approximately 50 per cent rated speed.
Grundfos Motor Book  215