Technical data

76
Input filter
Why an input filter?
An Input Filter is a filtration device to be installed
up-line from the frequency inverter and down-line
from the power feeding contactor.
The AC/DC rectifier at the inverter input generates
harmonic disturbance on the absorbed current
and returns disturbance generated by switching
components towards the mains.
This harmonic current causes voltage distortions on
the mains resulting in electromagnetic interference
phenomena.
This harmonic distortion is reduced by means of
line chokes, while disturbance is countered with
EMI filters (attenuation of EMI voltages) such as
those described below.
Note: the use of input filters reduces the inverter
input voltage. If required, these filters should be
installed up-line from the inverter in the following
order:
1. Mains supply
2. Line choke
3. EMI filter
4. Inverter
Line choke
- Line chokes are not mandatory: their use
depends on the system engineer’s need to reduce
harmonic distortion in the short circuit point, and
the need to reinforce the action of the EMI filter.
A line choke is normally used if the mains short
circuit power is lower than 1%.
- A line choke is recommended for the ACU201
and ACU401 frequency inverter series in the
presence of high continuous input current
required by the application, in order to increase
the lifetime of the electrolytic capacitors.
- A line choke is always required in single and
two-phase operation of the ACU201 frequency
inverters.
EMI filter
- An EMI filter can be used in order to achieve
Class “A” (groups 1, 2) or Class “B” interference
suppression
- The EMI filter is available in a low leakage
current version for special applications.
- The EMI - filter is part of the standard outfit in sizes
of up to 4.0 kW and it is supplied as an optional for
higher sizes in an internal (up to 7.5 kW) or external
(above 7.5 kW) version.
ACTIVE CUBE inverter - Line choke / EMI filter combination
Compliance with
Class A (Group 2)
Compliance with
Class A (Group 1)
Compliance with
Class B
Motor cable length
< 10 m < max* < 10 m < max* < 10 m < max*
ACU 1
(standard internal filter)
Standard external choke external choke external filter external choke external filter
ACU 2
(standard internal filter)
Standard external choke external choke external filter external choke external filter
ACU 3
internal filter
or
external choke
internal filter
or
external choke
internal filter
+
external choke
internal filter
+
external choke
internal filter
+
external choke
external filter
ACU 4 external choke external choke external filter external filter external filter
external filter
+
external choke
ACU 5 external choke external choke external filter external filter external filter
external filter
+
external choke
ACU 6 external choke external choke external filter external filter external filter external filter
ACU 7
external choke external filter external filter external filter — —
* See the operation manual
Power
feeding line
Line choke
Power
feeding line
EMI filter