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3.3 Electrical connection
The electrical connections must be carried out by an
authorised electrician in accordance with local
regulations.
The operating voltage and frequency are marked on
the motor nameplate.
Make sure that the motor is suitable for the power
supply of the installation site.
Carry out the electrical connections as shown on the
motor nameplate or in the wiring diagram on the
back of the terminal box cover.
For further information, contact the motor supplier.
3.3.1 Frequency converter operation
You can connect all three-phase motors 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 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.
When the pump is operated via a frequency
converter, check the following operating conditions:
DANGER
Electric shock
Death or serious personal injury
- Before you remove the terminal box
cover and before you remove or
dismantle the pump, make sure that the
power supply has been switched off and
that it cannot be accidentally switched
on.
DANGER
Electric shock
Death or serious personal injury
- Whenever you use powered equipment
in explosive surroundings, observe the
rules and regulations generally or
specifically imposed by the relevant
responsible authorities or trade
organisations.
If in doubt whether the supplied motor can
handle frequency converter operation,
contact the motor supplier.
Operating
conditions
Action
2-, 4- and 6-pole
motors, frame
size 225 and
larger
Ensure that the non-drive-end
motor bearing is electrically
isolated.
Noise-critical
applications
Fit a dU/dt filter between the
motor and the frequency
converter. It reduces the voltage
peaks and thus the noise.
Particularly
noise-critical
applications
Fit a sinusoidal filter.
Cable length
Fit a cable that meets the
specifications laid down by the
frequency converter supplier.
The length of the cable between
the motor and frequency
converter affects the motor
load.
Supply voltage
up to 500 V
Make sure that the motor is
suitable for frequency converter
operation.
Supply voltage
between 500 V
and 690 V
•
Fit a dU/dt filter. It reduces
the voltage peaks and thus
the noise.
•
Or make sure that the motor
has reinforced insulation.
Supply voltage
of 690 V and
upwards
•
Fit a dU/dt filter.
•
Make sure that the motor
has reinforced insulation.
