Frame R8I And Multiples; Dc Connection And Capacitor Charging - ABB ACS880-104 Hardware Manual

32 Hardware description
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Frame R8i and multiples

Frame R8i modules are used to achieve output powers from approximately 250 kW upwards.
Frame R8i modules are used in single or parallel configurations. R8i modules run on wheels,
and can easily be removed from the cubicle for cable installation or service.
The motor connection is via a quick connector at the back of the module that couples when
the module is inserted into the cubicle. Each parallel-connected module is cabled separately
to the motor, or connected by busbars to adjacent modules to reduce the number of cables.
It is also possible to build an AC bus from each module to a separate output cubicle.
As standard, the cooling fan is automatically speed-controlled according to the loading of
the inverter module. The fan is supplied internally.
If a direct-on-line fan (option +C188) is used, the user must connect the fan supply (400 V AC
/ 50/60 Hz or 320 V AC / 60 Hz) to the terminal block [X50].
Internal du/dt filtering is optional for single-module 400/500 volt inverter units, but mandatory
with all 690 volt units and all parallel-connected modules.
Frame R8i (and multiples, if any) modules are controlled by a single BCU control unit installed
separately from the module(s). The control unit is connected to each module by a fiber optic
link. The control unit can be powered from the module (terminal block X53), from an external
24 V DC supply, or both for redundancy. The control unit contains the basic I/Os and slots
for optional I/O modules. Other equipment is primarily installed on separate mounting plates.

DC connection and capacitor charging

The module must be equipped with external DC fuses.
A DC switch/disconnector can be installed if quick isolation of the module from the DC bus
is required.
A capacitor charging circuit must be fitted if:
• the module is connected to the DC bus through a DC switch/disconnector, or
• the module is directly connected to the DC bus and the supply unit of the system does
not have a charging capability.
The charging circuit design presented in this manual consists of a charging switch, resistors
and a charging controller. When the module is connected to an energized DC bus, the
charging switch is closed first. When the charging is finished, the main DC
switch/disconnector can be closed and the charging switch opened. The module will not
start if the charging switch is closed.
Common mode filtering is implemented by running the DC bus through ferrite cores at the
input of the module.