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Internal Active Filter Oper...
programmed master LCP. The LCP is removable to prevent
undesired program changes. With an optional remote
mounting kit, the LCP can be mounted in a remote
location of up to 10 ft [3 m] away.
3
3
Control terminals, which are programmable for specific
functions, are provided for input. In addition, output
terminals provide signals to control peripheral devices or
for reporting the status of monitored filter functions. The
control card logic is also capable of communicating,
through its serial link, with outside devices such as
personal computers or programmable logic controllers
(PLC).
The control card can also provide two voltage supplies for
use from the control terminals. The 24 V DC is used for
switching functions such as start and stop. The 24 V DC
supply also provides 200 mA of power, part of which may
be used to power external devices. A 10 V DC supply on
terminal 50 is rated at 17 mA is also available for use.
3.2.3 Active Filter Card
The active filter card (AFC) performs calculations based on
internal currents from IGBT current transducers, external
currents from customer-supplied current transformers
(CTs), and voltage information from the DC bus. These
calculations are used to control the output current of the
active filter for harmonic suppression on line power. The
AFC also interfaces with the power card. The power card
provides information about the DC bus voltage and the
output current from the internal IGBT current transducers
in the inverter. In addition, the AFC receives input from the
internal AC capacitor current transducers. The external CTs
also interface with the AFC and are mounted in the
customer electrical supply system. (In the LHD, the external
CTs are mounted in front of the Adjustable frequency
drive.)
The customer-supplied external CT secondary coil can be
rated with nominal currents of 5 A or 1 A, depending on
the secondary rating of the CT. Connectors on the AFC
board correspond to these current ratings.
3-2
VLT Advanced Active Filter AAF006 D and E Frames Service Manual
Figure 3.2 Active Filter Card
1
MK101 (5 A external
connector)
2
MK108 (1 A external
connector)
3
MK103
Table 3.2
3.2.4 Control to Power Interface
The control to power interface isolates the high voltage
components of the power section from the low voltage
signals of the control section. The interface section consists
of the power card and the gate drive card. Much of the
fault processing is handled by the control card. The power
card provides conditioning of these signals along with
scaling of current and voltage feedbacks. The power card
contains a switch mode power supply (SMPS) which
provides the unit with 24 V DC, +18 V DC, –18 V DC and 5
V DC operating voltages. The control and interface circuitry
is powered by the SMPS. The SMPS is supplied by the DC
bus voltage. The filter can be purchased with an optional
secondary SMPS which is powered from a customer-
supplied 24 V DC source. This secondary SMPS provides
power to the control circuitry when line power input is
disconnected and can maintain communication options
when the filter is not powered from line power. Circuitry
for controlling the cooling fans is also provided on the
power card. The gate signals from the control card to the
transistors (IGBTs) are isolated and buffered on the gate
drive card.
®
MG90Z122 - VLT
is a registered Danfoss trademark
4
3
1
2
4
MK107
5
MK100
6
FK100
5
6
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