09/01 AWB8230-1412GB
Electrical connection
35
Motor filters, dv/dt-filters, sinusoidal filters
Motor filters (chokes) compensate for capacitive currents with
long motor cables and with grouped drives (multiple connection of
parallel drives to a single inverter).
The use of motor filters is recommended (observe the manufac-
turers instructions):
• with grouped drives
• with the operation of three-phase current asynchronous motors
with maximum frequencies greater than 200 Hz,
• with the operation of reluctance motors or permanently-excited
synchronous motors with maximum frequencies greater than
120 Hz.
With dv/dt filters, the voltage on the motor terminals are limited
to values less than 500 V/ms. They should be applied with motors
with unknown or insufficient withstand voltage for the insulation.
When sinusoidal filters are used, the motors are supplied with
voltage and current which is almost sinusoidal.
Bypass operation
If you want to have the option of operating the motor with the
frequency inverter or directly from the mains supply, the incoming
supplies must be locked mechanically:
Caution!
During the engineering phase, the voltage drop asso-
ciated with motor filters and dv/dt filters must be consi-
dered as it can be up to 4 % of the frequency inverter
output voltage.
Caution!
During the engineering phase, it is necessary to consider
that the sinusoidal filter on the output voltage and the
switching frequency of the frequency inverter must be
adapted to suit each other.
The voltage drop on the sinusoidal filter can be up to
15 % of the frequency inverter output voltage.
Caution!
Switch-over between the frequency inverter and the
mains supply must be undertaken in a no voltage state.
Warning!
The frequency inverter outputs (U, V, W) may not be
connected to the mains voltage (destruction of the device,
danger of fire).
Figure 29: Bypass motor control
Q1
I
>
I
>
I
>
K1M
S1
M1
G1
M
3h
L1
L2
L3
L1 L2 L3
UVW
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