Starting Method; Direction Of Rotation; Protection Against Electro-Chemical Way; Corrosion - Grundfos SMD Installation And Operating Instructions Manual

6.6 Starting method

6.6.1 SMD
Continuous operation
Direct start is possible throughout the entire power
range.
Intermittent operation
For 1.9 kW and larger motors use a soft starter or a
frequency converter. See section Frequency
converter operation.
6.6.2 SMG
Continuous operation
Motors up to 1.6 kW can be started by direct starting.
Use star-delta starting, soft starter or frequency
converter for 2 kW and larger motors. See section
Frequency converter operation.
Intermittent operation
Use star-delta starting, soft starter or frequency
converter throughout the entire power range.
6.6.3 SFG
Continuous operation
Start the flowmakers by star-delta starting, soft starter
or frequency converter. See section Frequency
converter operation.
Intermittent operation
It is mandatory to start the flowmakers by
soft starter or frequency converter.

6.7 Direction of rotation

Once the electrical connections are set, check that
the propeller is rotating in the correct direction. When
viewed from the motor the propeller must rotate
clockwise.
An arrow on the motor housing shows the correct
direction of rotation.
If the propeller rotates in the wrong direction,
interchange two phases of the mains supply.
30
6.8 Protection against electro-chemical

corrosion

Two different metals or alloys cause electro-chemical
corrosion if they are connected by an electrolyte. This
applies if more than one mixer or flowmaker are
installed in the same tank. Use one of the following
additional protection methods:
• galvanic separation of the earth conductor from
the neutral conductor
• galvanic separation of the main supply by isolation
transformer
• anode kit.
Separate the earth conductor, so direct current
cannot flow through it. It must still function as a
protective conductor. This can be achieved with a
limiting unit, polarisation cell, anti-parallel diode or an
isolation transformer.
2
3
Protection against electro-chemical corrosion
Pos. Description
1 Limiting unit
2 Earth conductor
3 Isolation transformer
When using an isolation transformer, do
not alter the ratio between starting current
and rated current.
L1
L2
L3
N
PE
1
2