VLT
®
2800 Series
Introduction to VLT
2800
circuit are not overloaded, which would dramat ically
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 c omply 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
Galvanic Isolation (PELV).
■ Advanced motor protection
The frequency converter 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 mo tor switch, CTI.
To give the motor maximum protection against
overheating when it is cove red or blocked, or if the fan
should fail, you can install a thermistor and connect it
to the frequenc y 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 m otors linked in parallel.
MG.28.E9.02 - VLT is a registered Danfoss trademark
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