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.
2.3.4 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. It is easy for the user to program the required functions on the control panel or via serial communication.
2.3.5 Mains Protection
The FCD 300 Series is protected against the transients that may occur on the mains, such as coupling with a phase compensation system or transients
from fuses blown or when lightening strikes.
Rated motor voltage and full torque can be maintained down to approx. 10% undervoltage in the mains supply.
As all units in the FCD 300 Series have intermediate circuit coils, there is only a low amount of harmonic mains supply interference. This gives a good
power factor (lower peak current), which reduces the load on the mains installation.
2.3.6 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 current 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
inverter 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 function cuts out the inverter.
2.3.7 Reliable Galvanic Isolation
In the FCD 300 all digital inputs/outputs, analogue 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
the mains potential.
See section
Galvanic Isolation (PELV)
for further details.
2.3.8 Advanced Motor Protection
The FCD 300 Series has integral electronic motor protection.
The frequency converter calculates the motor temperature on the basis of current, frequency and time.
As opposed to traditional, bimetallic protection, electronic protection takes account of reduced cooling at low frequencies because of reduced fan speed
(motors 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 overheating 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.
2 Introduction to FCD 300
VLT
®
Decentral FCD 300 Design Guide
34
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
2
