Danfoss VLT Series Programming Manual page 48

Parameter Description
3.3.9 Trip at Motor Speed Low Limit
In 4-11 Motor Speed Low Limit [RPM] and 4-12 Motor Speed
Low Limit [Hz] 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
14-20 Reset Mode.
If the trip must take place at a rather exact speed (RPM), it
is recommended to set 0-02 Motor Speed Unit for RPM and
use slip compensation, which can be set in 1-62 Slip
Compensation.
NOTE
To achieve the highest accuracy with the slip compen-
sation, an Automatic Motor Adaptation (AMA) should be
performed. To be enabled in 1-29 Automatic Motor
Adaptation (AMA).
NOTE
Trip will not be active when using a normal stop- or coast
command.
1-86 Trip Speed Low [RPM]
Range: Function:
Size [ 0 - par. Set the desired motor speed for trip
related 4-13 RPM] 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 0-02 Motor Speed Unit is
set to [RPM].
1-87 Trip Speed Low [Hz]
Range: Function:
Size [ 0.0 - If the Trip Speed is set to 0, the
related par. 4-14 function is not active.
*
Hz]
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.
®
VLT HVAC Drive Programming Guide
NOTE
This parameter is only available if 0-02 Motor Speed Unit is
set to [Hz].
3.3.10 1-9* Motor Temperature
1-90 Motor Thermal Protection
Option:
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[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.
®
MG.11.CC.02 - VLT is a registered Danfoss trademark
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 (1-93 Thermistor Source).
•
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
motor frequency f
calculations estimate the need for
a lower load at lower speed due
to less cooling from the fan
incorporated in the motor.
No protection If the motor is continuously overloaded
and no warning or trip of frequency
converter is wanted.
Thermistor Activates a warning when the connected
warning thermistor in the motor reacts in the event
of motor over-temperature.
Thermistor trip Stops (trips) the frequency converter when
the connected thermistor in the motor
reacts in the event of motor over-
temperature.
ETR warning 1
ETR trip 1
*
ETR warning 2
ETR trip 2
ETR warning 3
ETR trip 3
ETR warning 4
3 3
and the rated
M,N
. The
M,N
47