Danfoss VLT Programming Guide

14-60 Function at Over Temperature
Option: 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 con-
verter should trip (trip locked) or derate the output current.
[0] * Trip 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.
[1] Derate If the critical temperature is exceeded the output current will be reduced until the allowable tem-
perature has been reached.
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.
Select
Function at Inverter Overload , par. 14-61 Function at Inverter Overload to automatically reduce pump speed until the output current is below
100% of the rated current (set in par. 14-62
Inv. Overload Derate Current ).
The
Function at Inverter Overload is an alternative to letting the frequency converter trip.
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
Inverter Thermal .
If par. 14-61
Function at Inverter Overload is set to Derate, the pump speed will be reduced when the counter exceeds 98, and stay reduced until the
counter has dropped below 90.7.
If par. 14-62
Inv. Overload Derate Current 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.
3 Parameter Description VLT
®
HVAC Drive Programming Guide
154 MG.11.C9.02 - VLT
®
is a registered Danfoss trademark
3

Danfoss VLT Specifications

General

Frequency	50/60 Hz
Enclosure	IP20, IP21, IP55, IP66
Series	VLT
Control Technique	Flux Vector Control
Output Voltage	0-Vinput
Control Method	Fieldbus
Communication Interface	PROFIBUS, CANopen
Protection Features	Overload, Overvoltage, Undervoltage, Short Circuit, Ground Fault
Cooling Method	Liquid Cooled
Storage Temperature	-25°C to +70°C
Relative Humidity	5-95% non-condensing
Altitude	Up to 1000m (3280ft) without derating, up to 4000m (13120ft) with derating
Operating Temperature	-10°C to +50°C (14°F to 122°F)