way, the inverter and the condensers in the intermedi-
ate circuit are not overloaded, which would dramati-
cally reduce the service life of the frequency converter.
The frequency converter offers temperature protection
as standard. If there is a thermal overload, this function
cuts out the inverter.
Reliable galvanic isolation
In the frequency converter 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, so that
they can be connected to the mains potential.
For further information see the section entitled
Gal-
vanic Isolation (PELV)
.
Advanced motor protection
The frequency converter has integral electronic motor
protection.
The frequency converter calculates the motor temper-
ature 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 par-
allel. 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.
See also the section entitled
Galvanic Isolation (PELV)
for further information.
NB!
This function cannot protect the individual
motors in the case of motors linked in par-
allel.
MG.27.E2.02 - VLT is a registered Danfoss trademark
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