3.3.9 Trip at Motor Speed Low Limit
In
4-11 Motor Speed Low Limit [RPM]
and
it is possible to set a minimum speed for
the motor in order to ensure proper oil distribution.
In some cases e.g. if operating in current limit because of a
defect in the compressor, the output motor speed can be
suppressed below Motor Speed Low Limit. To prevent
damage to the compressor it is possible to set trip limit. If
the motor speed drops below this limit, the frequency
converter will trip and issue an alarm (A49).
Reset will take place according to the selected function in
If the trip must take place at a rather exact speed (RPM), it
is recommended to set
for RPM and
use slip compensation, which can be set in
NOTE
To achieve the highest accuracy with the slip compen-
sation, an Automatic Motor Adaptation (AMA) should be
performed. To be enabled in
.
NOTE
Trip will not be active when using a normal stop- or coast
command.
1-86 Trip Speed Low [RPM]
Range:
Function:
Size
related
*
[ 0 - par.
4-13 RPM]
Set the desired motor speed for trip
limit. If the Trip Speed is set to 0, the
function is not active. If the speed at
any time after the start (or during a
stop) falls below the value in the
ameter, the drive will trip with an alarm
[A49] Speed Limit. Function at stop.
NOTE
This parameter is only available if
is
set to [RPM].
1-87 Trip Speed Low [Hz]
Range:
Function:
Size
related
*
[ 0.0 -
par. 4-14
Hz]
If the Trip Speed is set to 0, the
function is not active.
If the speed at any time after the start
(or during a stop) falls below the value
in the ameter, the drive will trip with
an alarm [A49] Speed Limit. Function at
stop.
NOTE
This parameter is only available if
is
set to [Hz].
3.3.10 1-9* Motor Temperature
1-90 Motor Thermal Protection
Option:
Function:
The frequency converter determines the
motor temperature for motor protection in
two different ways:
•
Via a thermistor sensor connected
to one of the analog or digital
inputs (
•
Via calculation (ETR = Electronic
Thermal Relay) of the thermal
load, based on the actual load
and time. The calculated thermal
load is comed with the rated
motor current I
M,N
and the rated
motor frequency f
M,N
. The
calculations estimate the need for
a lower load at lower speed due
to less cooling from the fan
incorporated in the motor.
[0]
No protection
If the motor is continuously overloaded
and no warning or trip of frequency
converter is wanted.
[1]
Thermistor
warning
Activates a warning when the connected
thermistor in the motor reacts in the event
of motor over-temperature.
[2]
Thermistor trip Stops (trips) the frequency converter when
the connected thermistor in the motor
reacts in the event of motor over-
temperature.
[3]
ETR warning 1
[4]
*
ETR trip 1
[5]
ETR warning 2
[6]
ETR trip 2
[7]
ETR warning 3
[8]
ETR trip 3
[9]
ETR warning 4
[10] ETR trip 4
ETR (Electronic Thermal Relay) functions 1-4 will calculate
the load when set-up where they were selected is active.
For example ETR-3 starts calculating when set-up 3 is
selected. For the North American market: The ETR
functions provide class 20 motor overload protection in
accordance with NEC.
Parameter Description
VLT
®
HVAC Drive Programming Guide
MG.11.CC.02 - VLT
®
is a registered Danfoss trademark
47
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