Grundfos SP Installation And Operating Instructions Manual page 16

Three-phase motors
Use three-phase motors with the proper size
and type of motor starter to ensure the motor is
protected against damage from low voltage,
phase failure, current imbalance and overload
current.
Use a properly sized starter with ambient-
compensated, class 10, extra quick-trip overload
relays or an MP204 to give the best possible
motor winding protection.
Each of the three motor legs must be
protected with overloads. The thermal
overloads must trip in less than 10 seconds at
locked rotor (starting) current. A three-phase
motor wiring diagram is shown in fig. 12.
CAUTION
Ensure that the pump is totally
Caution
submerged before you check the
direction of rotation. Severe damage
may be caused to the pump and
motor if they are run dry.
Fig. 12 Three-phase wiring diagram for Grundfos motors and other motor manufacturers
16
Pressure
switch
disconnect
Magnetic
starter
Green
Power supply
Fused
switch
Well
seal