Motor Thermal Protection - Danfoss VLT FC 100 Operating Instructions Manual

VLT HVAC Drive High Power Operating In-
structions
NB!
Installations with cables connected in a common
joint as in the illustration below, is only recommen-
ded for short cable lengths.
NB!
When motors are connected in parallel, par. 1-29
tomatic Motor Adaptation (AMA) cannot be used.
NB!
The electronic thermal relay (ETR) of the frequency
converter cannot be used as motor protection for the
individual motor in systems with parallel-connected
motors. Provide further motor protection by e.g.
thermistors in each motor or individual thermal relays
(circuit breakers are not suitable as protection).
LC lter

4.5.3 Motor Thermal Protection

The electronic thermal relay in the frequency converter has received
UL-approval for single motor protection, when par. 1-90
Protection is set for ETR Trip and par. 1-24 Motor Current is set to the
rated motor current (see motor name plate).
For thermal motor protection it is also possible to use the MCB 112 PTC
Thermistor Card option. This card provides ATEX certificate to protect
motors in explosion hazardous areas, Zone 1/21 and Zone 2/22. When
par. 1-90 Motor Thermal Protection is set to [20] ATEX ETR is com-
bined with the use of MCB 112, it is possible to control an Ex-e motor in
Problems may arise at start and at low RPM values if motor sizes are
widely different because small motors' relatively high ohmic resistance
in the stator calls for a higher voltage at start and at low RPM values.
Au-
explosion hazardous areas. Consult the programming guide for details
Motor Thermal on how to set up the drive for safe operation of Ex-e motors.
MG.11.F3.02 - VLT ® is a registered Danfoss trademark
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