Electrical Connection; Thermal Protection - Grundfos DWK Serie Montage- Und Betriebsanleitung

3.2 Electrical connection

DANGER
Electric shock
Death or serious personal injury
- A motor protector, set to rated current
+10 %, must be installed by the
customer.
- Make sure that all protective equipment
has been connected correctly.
DANGER
Electric shock
Death or serious personal injury
- It is not permitted to extend the pump
cable. Contact Grundfos to get the right
cable length.
DANGER
Electric shock
Death or serious personal injury
- The motor-protective circuit breaker of
the pump controller must include a
circuit which automatically disconnects
the power supply in case the protective
circuit for the pump is opened.
Carry out the electrical connection in
accordance with local regulations.
Do not install Grundfos control boxes and
pump controllers in potentially explosive
environments.
Connect the pump to a control box with a
motor protective relay with IEC trip class
10 or 15.
The pump must be connected to a main
switch with a minimum contact gap of 3
mm in all poles.
The classification of the installation site
must be approved by the local fire-fighting
authorities in each individual case.
The supply voltage and frequency are marked on the
pump nameplate. The voltage tolerance must be
within - 5 %/+ 5 % of the rated voltage. Make sure
that the motor is suitable for the power supply
available at the installation site.
All pumps are supplied with 10 m cable and a free
cable end.
Pumps with sensors must be connected to a GU01
or GU02 pump controller. See fig.
connected pumps or fig.
pumps. For further information, see the installation
and operating instructions for the selected control
box or pump controller at www.grundfos.com.
5 for DOL-
6 for star-delta-connected

3.3 Thermal protection

One thermal switch is built into the motor winding
and will break the circuit in case of over temperature.
In case of intermittent operation, with water level up
to half of the motor, the thermal switch inside the
motor winding might be activated and cause the
pump to stop.
The following thermal protections can be found in
DWK pumps, depending on the specific pump type:
• thermal switch (Bi-metallic) type PTO or Klixon
• circuit breaker - Klixon (connected to the star
point of the stator)
• thermal sensor PT100 (PCA Platinium chip).
The thermal switch must be connected according to
the wiring diagram fig. 5
alarm output will cause a motor stop in case of high
temperature in the motor.
The thermal switch must be connected to the control
wire of the power cable inside the pump and to the
safety circuit of the separate pump controller.
3.3.1 Checking after electrical connection
Use a multimeter to check the two signal wires of the
power cable. The circuit must be closed and the
resistance must be less than 1 Ohm.
or fig. 6. Make sure that the
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