Danfoss VLT Programming Guide

22-81 Square-linear Curve Approximation
Range: Function:
100 %* [0 - 100 %] Example 1:
Adjustment of this parameter allows the shape of the control curve to be adjusted.
0 = Linear
100% = Ideal shape (theoretical).
NB!
Please note: Not visible when running in cascade.
22-82 Work Point Calculation
Option: Function:
Example 1: Speed at System Design Working Point is known:
From the data sheet showing characteristics for the specific equipment at different speeds, simply
reading across from the H
DESIGN
point and the Q
DESIGN
point allows us to find point A, which is the
System Design Working Point. The pump characteristics at this point should be identified and the
associated speed programmed. Closing the valves and adjusting the speed until H
MIN
has been
achieved allows the speed at the no flow point to be identified.
Adjustment of par. 22-81
Square-linear Curve Approximation then allows the shape of the control
curve to be adjusted infinitely.
Example 2:
Speed at System Design Working Point is not known: Where the Speed at System Design Working
Point is unknown, another reference point on the control curve needs to be determined by means
of the data sheet. By looking at the curve for the rated speed and plotting the design pressure
3 Parameter Description VLT
®
HVAC Drive Programming Guide
214 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)