Electrical Connection; Motor Protection; Frequency Converter Operation - Grundfos DW series Montage- Und Betriebsanleitung

Model A:
The A models have an integrated level control
system.
By means of two electrodes, the level control system
measures the water level in the water level
compartment. The short electrode starts the pump
and the long one stops the pump.
When the pump has drained the pit/sump, the rubber
valve, situated next to the electrodes on top of the
motor housing, will draw in air to drain the pump.
When the A models are used for automatic operation
in deep pits/sumps, a non-return valve must be
mounted immediately after the discharge port to
prevent backflow and thus intermittent operation
when the pit/sump has been drained. See fig. 2.
Fig. 2 Model A

6. Electrical connection

The electrical connection of the pump should be
carried out in accordance with local regulations.
Warning
Connect the pump to an external mains
switch placed close to the pump and to a
motor-protective circuit breaker.
Make sure you can lock the mains switch
in OFF position (isolated). Type and
requirements as specified in EN 60204-1,
5.3.2.
The operating voltage and frequency are marked on
the nameplate. Voltage tolerance: ± 10 % of the
voltage stated on the nameplate. Make sure that the
motor is suitable for the electricity supply available at
the installation site.

6.1 Motor protection

All Grundfos DW pumps have a thermal switch built
into the stator windings.
All single-phase Grundfos DW pumps are supplied
with an operating capacitor.
For capacitor sizes, see the table below:
Pump type
DW.50.07.1
DW.50.08.1

6.2 Frequency converter operation

The DW pumps with integrated motor starter should
not be connected to a frequency converter, as this
may result in damage to the motor.
Frequency converter operation will often expose the
motor insulation system to a heavier load and cause
the motor to be more noisy than usual due to eddy
currents caused by voltage peaks.
In addition, large motors driven via a frequency
converter will be loaded by bearing currents.
Operating capacitor
[μF]
16
16
7