Electrical Connection; Frequency Converter Operation - Grundfos TP Serie Instrucciones De Instalación Y Funcionamiento

6. Electrical connection

Make the electrical connection in accordance with
local regulations.
Warning
Before removing the terminal box cover
and before any removal/dismantling of the
pump, make sure that the power supply
has been switched off.
Connect the pump to an external mains
switch with a minimum contact gap of 3
mm in all poles.
The operating voltage and frequency are marked on
the pump nameplate. Make sure that the motor is
suitable for the power supply on which it will be used.
Single-phase standard motors incorporate a thermal
switch and require no additional motor protection.
Three-phase motors must be connected to a motor
protection device.
Motors of 3 kW and up incorporate thermistors
(PTC). The thermistors are designed according to
DIN 44082.
Make the electrical connection as shown in the
diagram inside the terminal box cover.
The motors of twin-head pumps are to be connected
separately.
Do not start the pump until it has been
Caution
filled with liquid and vented.
12

6.1 Frequency converter operation

Motors types Siemens, MG 71 and MG 80
for supply voltages up to and including 440
Caution
V (see motor nameplate) must be
protected against voltage peaks higher
than 650 V between the supply terminals.
Grundfos motors
All three-phase Grundfos motors from frame size 90
and up can be connected to a frequency converter.
The connection of a frequency converter will often
have the effect that the motor insulation system is
loaded more and that the motor will be more noisy
than during normal operation. In addition, large
motors are more at risk of being loaded with bearing
currents caused by the frequency converter.
In the case of frequency converter operation,
consider the following:
• In 2-pole motors from 45 kW, 4-pole motors from
30 kW and 6-pole motors from 22 kW, one of the
motor bearings must be electrically insulated to
prevent damaging currents from passing through
the motor bearings.
• In the case of noise-critical applications, the
motor noise can be reduced by fitting an output
filter between the motor and the frequency
converter. In particularly noise-critical
applications, we recommend that you fit a
sinusoidal filter.
• The length of the cable between motor and
frequency converter affects the motor load.
Therefore, check that the cable length meets the
specifications laid down by the frequency
converter supplier. For supply voltages between
500 and 690 V, either fit a sinusoidal filter to
reduce voltage peaks or use a motor with
reinforced insulation.
• For supply voltages of 690 V, use a motor with
reinforced insulation and fit a sinusoidal filter.
Grundfos MG motors do not have
reinforced insulation. When it comes to
Note
reinforced insulation, other motor suppliers
are able to supply such motors as FPV
variants.
6.1.1 Other motor makes than Grundfos
Contact Grundfos or the motor manufacturer.