Grundfos SRG Installation And Operating Instructions Manual page 10

4.4.1 Starting method
Continuous operation
We recommend star-delta starting, soft starter or
frequency converter throughout the entire power
range.
Intermittent operation
Start via softstarter or frequency converter is
mandatory throughout the entire power range.
4.4.2 Wiring diagrams
U1 V1 W1 W2 U2 V2
Fig. 11 Three thermal switches (PTO)
Terminals Description
Ends of the three stator windings
1, 2, 3, 4, 5, 6
(U1, U2, V1, V2, W1, W2)
11, 12 Thermal switches (F6)
21, 22 Leak sensor in gearbox (B)
10
PTO LS PE
B
U1 V1 W1 W2 U2 V2
Fig. 12 Three PTC sensors
Terminals Description
Ends of the three stator windings
1, 2, 3, 4, 5, 6
(U1, U2, V1, V2, W1, W2)
PTC sensors (according to DIN 44
31, 32
081) (1, 2, 3)
21, 22 Leak sensor in gearbox (B)
4.4.3 Direction of rotation
When the electrical connections have been carried
out, check that the impeller is rotating in the correct
direction. When viewed from the motor, the impeller
must rotate clockwise. An arrow on the motor
housing shows the correct direction of rotation.
If the impeller rotates in the wrong direction,
interchange two phases of the mains supply (L1, L2,
L3).
4.4.4 Frequency converter operation
All SRG pumps are designed for frequency converter
operation for energy saving and for soft start. For
frequency converter operation, please observe the
following information:
• Requirements must be fulfilled.
• Recommendations ought to be fulfilled.
• Consequences must be considered.
PTC LS PE