Grundfos DPK Montage- Und Betriebsanleitung Seite 13

11.1 Pump controllers
The pumps must be connected to a control box with
a motor protection relay with IEC trip class 10 or 15.
The pumps can be controlled by the following LC and
LCD pump controllers:
• LC 107, LCD 107 with air bells
• LC 108, LCD 108 with float switches
• LC 110, LCD 110 with water level electrodes.
LC controllers are for single-pump installations.
LCD controllers are for two-pump installations.
In the following description, "level switch" can be air
bells, float switches or water level electrodes,
depending on the pump controller selected.
The LC controller is fitted with two or three level
switches: One for start and one for stop of pump.
The third level switch, which is optional, is for high-
level alarm.
The LCD controller is fitted with three or four level
switches: One for common stop and two for start of
the pumps. The fourth level switch, which is optional,
is for high-level alarm.
For further information, see the installation and
operating instructions for the pump controller
selected.
E1 E2 E3
Max.
Min.
Fig. 9 Pump controllers
11.2 GU01 and GU02
GU01 is a monitoring device for monitoring the stator
temperature and water penetration into the motor.
It receives a digital signal.
GU02 is a monitoring device for monitoring stator
and bearing temperature as well as water
penetration into the motor. It receives an analog
signal.
Both monitoring devices must be connected to the
control panel via a relay.
GU01 and GU02 are manufactured for Grundfos.
For further information, please contact your local
Grundfos company.
11.3 Frequency converter operation
11.3.1 Recommendations
Before installing a frequency converter, calculate the
lowest allowable frequency in the installation in order
to avoid zero flow.
• Do not reduce the motor speed to less than 30 %
of rated speed.
• Keep the flow velocity above 1 m/sec.
• Let the pump run at rated speed at least once a
day in order to prevent sedimentation in the
piping system.
• Do not exceed the frequency indicated on the
nameplate. In this case there is risk of motor
overload.
• Keep the motor cable as short as possible.
The peak voltage will increase with the length of
the motor cable. See data sheet for the frequency
converter used.
• Use input and output filters on the frequency
converter. See data sheet for the frequency
converter used.
11.3.2 Possible consequences
Max.
When operating the pump via a frequency converter,
please be aware of these possible consequences:
S1
• The locked-rotor torque will be lower. How much
Min.
lower will depend on the frequency converter
S3
type. See the installation and operating
instructions for the frequency converter used for
information on the locked-rotor torque available.
• The working condition of bearings and shaft seal
may be affected. The possible effect will depend
on the application. The actual effect cannot be
predicted.
• The acoustic noise level may increase. See the
installation and operating instructions for the
frequency converter used for advice as to how to
reduce the acoustic noise.
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