Danfoss VLT HVAC Series Programming Manual page 267

VLT ® HVAC Drive Programming Guide
25-43 De-staging Threshold
Range:
0 %* [0 - 100 %]
25-44 Staging Speed [RPM]
Range:
0 RPM* [0 - 0 RPM]
Function:
When removing a fixed speed pump, in order to prevent an undershoot of pressure, the variable
speed pump ramps up to a higher speed. When the variable speed pump reaches the "De-staging
Speed" the fixed speed pump is de-staged. The De-staging Threshold is used to calculate the speed
of the variable speed pump when the de-staging of the fixed speed pump occurs. The calculation
of the De-staging Threshold is the ratio of par.4-11
Speed Low Limit [Hz] , to the par.4-13
Limit [Hz]
, expressed in percent.
De-staging Threshold must range from
Motor Speed Low Limit and n
HIGH
Function:
Readout of the below calculated value for Staging Speed. When adding a fixed speed pump, the
variable speed pump ramps down to a lower speed in order to prevent an overshoot of pressure.
When the variable speed pump reaches the "Staging Speed" the fixed speed pump is staged on.
Staging Speed calculation is based on par.25-42
Limit [RPM]
.
Staging Speed is calculated with the following formula:
STAGE
%
=
100
STAGE HIGH
where n is Motor Speed High Limit and n
HIGH
MG.11.C6.22 - VLT ® is a registered Danfoss trademark
Motor Speed Low Limit [RPM]
Motor Speed High Limit [RPM] or par.4-14
LOW
= × 100 % to 100%, where n
HIGH
STAGE
%
is Motor Speed High Limit.
Staging Threshold
, and par.4-13
is the value of Staging Threshold.
STAGE100%
3 Parameter Description
3
or par.4-12 Motor
Motor Speed High
is
LOW
Motor Speed High
3-243