Danfoss VLT DMS 300 Manual page 65

The decentral concept
The FCD 300 Adjustable speed drive is designed
for decentral mounting, e.g. in the food and
beverage industry, in the automotive industry, or
for other material handling applications.
With the FCD 300 it is possible to utilize the cost saving
potential by placing the power electronics decentrally,
and thus make the central panels obsolete saving cost,
space and effort for installation and wiring.
The unit is flexible in its mounting options for as
well stand-alone mounting and motor-mounting. It
is also possible to have the unit pre-mounted on
a Danfoss Bauer geared motor (3 in one solution).
The basic design with a plugable electronic part and
a flexible and "spacious" wiring box is extremely
service-friendly and easy to change electronics
without the need for unwiring.
The FCD 300 is a part of the VLT variable frequency drive
family, which means similar funcionality, programming,
and operating as the other family members.
FCD 300 control principle
A variable frequency drive is an electronic unit
which is able to infinitely variably control the rpm
of an AC motor. The variable frequency converter
governs the motor speed by converting the regular
voltage and frequency from AC line, e.g. 400 V /
50 Hz, into variable magnitudes. Today the variable
frequency drive-controlled AC motor is a natural
part of all types of automated plants.
The FCD 300 Series has an inverter control system
called VVC (Voltage Vector Control). VVC controls an
induction motor by energizing with a variable frequency
and a voltage suitable for it. If the motor load changes,
so does its energizing and speed. That is why the
motor current is measured on an ongoing basis,
and a motor model is used to calculate the actual
voltage requirement and slip of the motor.
Programmable inputs and outputs in four Setups
In the FCD 300 Series it is possible to program the
different control inputs and signal outputs and to select
four different user-defined Setups for most parameters.
MG.90.F2.22 - VLT is a registered Danfoss trademark
Decentral Solutions
It is easy for the user to program the required functions
on the control panel or via serial communication.
AC input protection
The FCD 300 Series is protected against the transients
that may occur on the AC line, such as coupling
with a phase compensation system or transients
from blown fuses or lightning strikes.
Rated motor voltage and full torque can be maintained
down to approx. 10% undervoltage in the mains supply.
As all 400 V units in the FCD 300 Series have
intermediate circuit coils, there is only a low amount
of harmonic electrical supply interference. This gives
a good power factor (lower peak current), which
reduces the load on the electrical installation.
Variable frequency drive protection
The current measurement in the intermediate circuit
constitutes perfect protection of the FCD 300
Series in case there is a short-circuit or a ground
fault on the motor connection.
Constant monitoring of the intermediate circuit
current allows switching on the motor output,
e.g. by means of a contactor.
Efficient monitoring of the electrical supply means
that the unit will stop in the case of a phase drop-out
(if the load exceeds approx. 50%). In this way, the
inverter and the capacitors in the intermediate circuit
are not overloaded, which would dramatically reduce
the service life of the variable frequency drive.
The FCD 300 Series offers temperature protection
as standard. If there is a thermal overload, this
function cuts out the inverter.
Reliable galvonic isolation
In the FCD 300 all digital inputs/outputs, analog
inputs/outputs and the terminals for serial
communication are supplied from or in connection
with circuits that comply with PELV requirements.
PELV is also complied with in relation to relay
terminals at max. 250 V, so that they can be
connected to AC line potential.
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