Danfoss VLT AQUA Drive FC 202 Programming Manual page 141

Parameter Description
14-59 Actual Number of Inverter Units
This parameter is only relevant for high-power frequency
converters.
Range: Function:
Size related [ 1 - 1 ] Sets the actual number of operating
*
inverter units.
3.13.7 14-6* Auto Derate
This group contains parameters for derating the frequency
converter if there is high temperature.
14-60 Function at Over Temperature
If either heat sink or control card temperature exceeds a
programmed temperature limit, a warning is activated. If the
temperature increases further, select whether the frequency
converter should trip (trip lock) or derate the output current.
Option: Function:
[0] Trip The frequency converter trips (trip
lock) and generates an alarm. Cycle
power to reset the alarm, but it does
not allow restart of the motor until the
heat sink temperature has dropped
below the alarm limit.
[1] Derate If the critical temperature is exceeded,
*
the output current is reduced until the
allowable temperature has been
reached.
3.13.8 No Trip at Inverter Overload
In some pump systems, the frequency converter has not
been sized properly to yield the current needed in all
points of the operational flow-head characteristic. At these
points, the pump needs a current higher than the rated
current of the frequency converter. The frequency
converter can yield 110% of the rated current continuously
for 60 s. If still overloaded, the frequency converter
normally trips (causing the pump to stop by coasting) and
issues an alarm.
MG20OB02
Programming Guide
Current
% of rated
Inverter
load
counter
Illustration 3.55 Output Current in Overload Condition
If the pump is unable to run continuously with the
demanded capacity, run it at reduced speed for a while.
Select parameter 14-61 Function at Inverter Overload to
automatically reduce pump speed until the output current
is below 100% of the rated current (set in
parameter 14-62 Inv. Overload Derate Current).
Parameter 14-61 Function at Inverter Overload is an
alternative to letting the frequency converter trip.
The frequency converter estimates the load on the power
section with an inverter load counter, which causes a
warning at 98% and a reset of the warning at 90%. At the
value 100%, the frequency converter trips and issues an
alarm.
Status for the counter can be read in
parameter 16-35 Inverter Thermal.
If parameter 14-61 Function at Inverter Overload is set to [3]
Derate, the pump speed is reduced when the counter
exceeds 98%, and stays reduced until the counter has
dropped below 90.7%.
If parameter 14-62 Inv. Overload Derate Current is set to for
example 95%, a steady overload causes the pump speed to
fluctuate between values corresponding to 110% and 95%
of rated output current for the frequency converter.
14-61 Function at Inverter Overload
Is used if there is steady overload beyond the thermal limits
(110% for 60 s).
Option:
[0] Trip
[1] Derate Reduces pump speed to decrease the load on the
*
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110
105
100
95
~ ~
60s
Desired current>100%
100
98
90.7
Warning Warning
Function:
The frequency converter trips and issues an alarm.
power section, allowing this to cool down.
3 3
Time
Time
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