Danfoss VLT FC 100 Series Programming Manual page 131

®
VLT HVAC Drive Programming Guide
14-60 Function at Overtemperature
Option:
* Trip
[0]
[1] Derate
3.14.9. 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 will need a current higher than the rated current of the frequency converter. The frequency converter can yield
110% of the rated current continuously for 60 sec. If still overloaded, the frequency converter will normally trip (causing the pump to stop by coasting)
and provide an alarm.
It may be preferable to run the pump at reduced speed for a while in case it is not possible to run continuously with demanded capacity.
Function at Inverter Overload
Select
Derate Level
, par. 14-62).
Function at Inverter Overload
The
The frequency converter estimates the load on the power section by means of an inverter load counter, which will cause a warning at 98% and a reset
of the warning at 90%. At the value 100%, the frequency converter trips and provides an alarm.
Status for the counter can be read in par. 16-35,
Function at Inverter Overload
If par. 14-61,
counter has dropped below 90.7.
Derate Level
If par. 14-62, , is set e.g. to 95% a steady overload will cause the pump speed to fluctuate between values corresponding to 110% and 95%
of rated output current for the frequency converter.
Function:
If either heatsink or control card temperature exceeds a factory-programmed temperature limit, a warning will
be activated. If the temperature increases further, select whether the frequency converter should trip (trip
locked) or derate the output current.
The frequency converter will trip (trip locked) and generate an alarm. Power must be cycled to reset the alarm,
but will not allow restart of the motor until the heat sink temperature has dropped below the alarm limit.
If the critical temperature is exceeded the output current will be reduced until the allowable temperature has
been reached.
, par 14-61 to automatically reduce pump speed until the output current is below 100% of the rated current (set in
is an alternative to letting the frequency converter trip.
Inverter Thermal
.
, is set to Derate, the pump speed will be reduced when the counter exceeds 98, and stay reduced until the
MG.11.C5.02 - VLT ® is a registered Danfoss trademark
3. Parameter Description
131
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