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DANGER
Electric shock
Death or serious personal injury
‐
Before the first startup, check the cable
for visible defects to avoid short
circuits.
Frequency converter operation
In principle, all three-phase motors can be connected
to a frequency converter.
However, frequency converter operation often
exposes the motor insulation system to a heavier load
and causes the motor to be more noisy.
For frequency converter operation, observe the
following:
•
The thermal protection of the motor must be
connected.
•
Peak voltage and dU/dt must be in accordance
with the table below. The values stated are
maximum values supplied to the motor terminals.
The cable influence is not taken into account.
See the frequency converter data sheet
regarding the actual values and the cable
influence on the peak voltage and dU/dt.
•
Set the frequency converter U/f ratio according to
the motor data.
•
Use a screened power cable if there is a risk that
electrical noise may disturb other electrical
equipment.
When operating the pump by a frequency converter,
consider the following:
•
The locked-rotor torque can be lower depending
on the type of the frequency converter.
•
The noise level may increase. See the
installation and operating instructions for the
frequency converter of choice.
Maximum repetitive
peak voltage
[V]
850
Frequency converter use may reduce the
life span of the bearings and the shaft
seal, depending on 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 frequency converter of
choice.
Level controllers
The liquid level can be controlled by the Grundfos LC
level controllers.
Suitable level controllers:
Maximum dU/dt U
400
N
V
[V/μ sec.]
2000
•
LC 231: compact solution with certified motor
protection for single- and dual-pump versions.
•
LC 241: cabinet solution offering modularity and
customisation for single- and dual-pump
versions.
In the following description, "level switches" can be air
bells, float switches or electrodes depending on the
selected pump controller.
Depending on the security levels and the number of
pumps, level switches can be used in the following
setups:
•
Dry run (optional)
•
Stop
•
Start pump 1 (single-pump version)
•
Start pump 2 (dual-pump version)
•
High level (optional)
Analogue level transmitters can be used, and all
levels can be customised. Level switches can be
used with level transmitters, for dry-run protection and
high level alarm.
The pump must not run dry. Install an
additional level switch to ensure that the
pump is stopped in case the stop level
switch is not operating.
Installing level switches
When installing the level switches, observe the
following points:
•
To prevent air intake and vibrations, install the
stop level switch, so the pump is stopped before
the liquid level is lowered to the middle of the
motor housing.
•
Install the start level switch, so the pump is
started at the required level. The pump must
always start before the liquid level reaches the
bottom inlet pipe.
•
Always install the high-level alarm switch about
10 cm above the start level switch. However, the
alarm must always be given before the liquid
level reaches the inlet pipe.
For further settings and information, see the
installation and operating instructions for the selected
level controllers.
Startup
Before starting the product:
•
Make sure that the fuses have been
removed.
•
Make sure that all protective
equipment has been connected
correctly.
•
Check the oil level.
•
Test the insulation resistance.
9
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