Grundfos SE - Page 22

Frequency converter use may reduce the
lifespan of the bearings and the shaft seal,
depending on the operating mode and
other circumstances.
For more information about the frequency converter
operation, see the data sheet and the installation and
operating instructions for the selected frequency
converter.
General conditions for frequency converter
operation
All motors used with frequency converter must be
protected against voltage peaks and dU/dT according
to IEC60034-25 Figure 14 - Curve A.
Grundfos recommends using insulated bearing
systems in installations where common mode
currents can be a problem. It is generally
recommended to use insulated bearings from the
following performance ranges:
• 45kW / 2-pole
• 30kW / 4-pole
• 22kW / 6-pole.
Use screened cables for frequency converter
operation.
• Screened power cables to comply with EMC
regulations.
• Screened sensor cables to protect the signals
against electromagnetic interference.
Mains-dependent conditions for frequency
converter operation
200-240 V
No output filters are required for frequency converter
operated pumps with up to 240 V mains voltages.
380-500 V
For frequency converter operated pumps with less
than 25 m power cable length and mains supply up to
460 V, no additional motor protection is required
against voltage peaks.
If the power cable length is longer than 25 m, or the
mains supply is higher than 460 V, sine-wave filters
are required.
500 V and above
Always use sine-wave filters for pumps marked for
500 V or higher voltages.
Pumps with reinforced motor insulation
can be supplied as an option for motors
above 22 kW. These motor stators will be
according to IEC60034-25, this can
eliminate the need for sine-wave filters.
Protection against common mode currents
is still needed according to the
specification mentioned above.
Power cable data
The minimum size of the ground conductor must be equal to or bigger than the phase conductor.
The top cover of the explosion-proof pumps is provided with an external ground terminal to ensure
the connection to the ground. The electrical installation must include an external connection from this
terminal to the ground. The ground conductor must comply with all electrical safety regulations in
force.
Before installation and the first startup of the pump, check the condition of the cable to avoid short
circuits.
Sensors
Switch and sensor specification
Ex sensor versions come with 2 moisture switches
and 1 optional dry running switch.
Sensor
version
Standard
and
Standard Ex
V1 and V1
Ex
V2
and
V2 Ex
Thermal
switches /
PTC
● ● ●
Moisture
switch
● ● ●
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English (GB)