Danfoss VLT FCD 305 Design Guide

VLT
®
FCD Series
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 se-
lect four different user-defined Setups for most
parameters. It is easy for the user to program the re-
quired functions on the control panel or via serial
communication.
■ Mains protection
The FCD 300 Series is protected against the tran-
sients that may occur on the mains, such as
coupling with a phase compensation system or tran-
sients from fuses blown or when lightening strikes.
Rated motor voltage and full torque can be main-
tained down to approx. 10% undervoltage in the
mains supply.
As all 400 V units in the FCD 300 Series have inter-
mediate circuit coils, there is only a low amount of
harmonic mains supply interference. This gives a
good power factor (lower peak current), which re-
duces the load on the mains installation.
■ Frequency converter protection
The current measurement in the intermediate circuit
constitutes perfect protection of the FCD 300 Series
in case there is a short-circuit or an earth fault on
the motor connection.
Constant monitoring of the intermediate circuit cur-
rent allows switching on the motor output, e.g. by
means of a contactor.
Efficient monitoring of the mains 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 in-
verter and the capacitors in the intermediate circuit
are not overloaded, which would dramatically reduce
the service life of the frequency converter.
The FCD 300 Series offers temperature protection
as standard. If there is a thermal overload, this func-
tion cuts out the inverter.
■ Reliable galvanic isolation
In the FCD 300 all digital inputs/outputs, analogue
inputs/outputs and the terminals for serial communi-
cation 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 the
mains potential.
See section Galvanic Isolation (PEL V) for further de-
tails.
■ Advanced motor protection
The FCD 300 Series has integral electronic motor
protection.
The frequency converter calculates the motor tem-
perature on the basis of current, frequency and time.
As opposed to traditional, bimetallic protection, elec-
tronic protection takes account of reduced cooling at
low frequencies because of reduced fan speed (mo-
tors with internal fan). This function cannot protect
the individual motors when motors are connected in
parallel. Thermal motor protection can be compared
to a protective motor switch, CTI.
To give the motor maximum protection against over-
heating when it is covered or blocked, or if the fan
should fail, you can install a thermistor and connect it
to the frequency converter’s thermistor input (Digital
input), see parameter 128 Thermal motor protection.
NB!:
This function cannot protect the individual
motors in the case of motors linked in parallel.
MG.04.A1.02 - VLT is a registered Danfoss trade mark
6

Danfoss VLT FCD 305 Specifications

General

Brand	Danfoss
Model	VLT FCD 305
Category	DC Drives
Language	English