Danfoss vlt FC 102 - Page 244

25-43 Destaging Threshold
Range: Function:
Size
related*
[ 0 - 100 %] When removing a xed-speed
pump to prevent an undershoot of
pressure, the variable-speed pump
ramps up to a higher speed. When
the variable-speed pump reaches
the destaging speed, the xed-
speed pump is destaged. The
destaging threshold is used to
calculate the speed of the variable-
speed pump when the destaging of
the xed-speed pump occurs. The
calculation of the destaging
threshold is the ratio of
parameter 4-11 Motor Speed Low
Limit [RPM] or parameter 4-12 Motor
Speed Low Limit [Hz], to
parameter 4-13 Motor Speed High
Limit [RPM] or parameter 4-14 Motor
Speed High Limit [Hz], expressed in
percent.
Destaging threshold must range
from
STAGE % = 
LOW
HIGH
 × 100 % to 100%,
where n
LOW
is motor speed low
limit and n
HIGH
is motor speed high
limit.
130BA367.10
3
5
0
1
Seconds
Variable speed
pump
Fixed speed
pump
Motor speed
high limit
Destaging
speed
Motor speed
low limit
Illustration 3.85 Destaging Threshold
25-44 Staging Speed [RPM]
Range: Function:
0 RPM* [000 - 0
RPM]
Readout of the calculated value for
staging speed. When adding a
xed-speed pump to prevent an
overshoot of pressure, the variable-
speed pump ramps down to a
lower speed. When the variable-
speed pump reaches the staging
speed, the xed-speed pump is
staged on. Staging speed
calculation is based on
parameter 25-42 Staging Threshold
and parameter 4-13 Motor Speed
High Limit [RPM].
Staging speed is calculated with the
following formula:
25-44 Staging Speed [RPM]
Range: Function:
η
STAGE
 = η
HIGH
η
STAGE %
100
where n
HIGH
is motor speed high
limit and n
STAGE100%
is the value of
staging threshold.
25-45 Staging Speed [Hz]
Range: Function:
0 Hz* [0 - 0 Hz] Readout of the calculated value for
staging speed. When adding a
xed-speed pump to prevent an
overshoot of pressure, the variable-
speed pump ramps down to a
lower speed. When the variable-
speed pump reaches the staging
speed, the xed-speed pump is
staged on. Staging speed
calculation is based on
parameter 25-42 Staging Threshold
and parameter 4-14 Motor Speed
High Limit [Hz].
Staging speed is calculated with the
following formula:
STAGE = HIGH
STAGE %
100
where n
HIGH
is
motor speed high limit and
n
STAGE100%
is the value of staging
threshold.
25-46 Destaging Speed [RPM]
Range: Function:
0 RPM* [000 - 0
RPM]
Readout of the calculated value for
destaging speed. When removing a
xed-speed pump to prevent an
undershoot of pressure, the
variable-speed pump ramps up to a
higher speed. When the variable
speed pump reaches the destaging
speed, the xed-speed pump is
destaged. Destaging speed is
calculated based on
parameter 25-43 Destaging Threshold
and parameter 4-13 Motor Speed
High Limit [RPM].
Destaging speed is calculated with
the following formula:
DESTAGE = HIGH
DESTAGE %
100
where n
HIGH
is
motor speed high limit and
n
DESTAGE100%
is the value of
destaging threshold.
Parameter Descriptions
VLT
®
HVAC Drive FC 102
242 Danfoss A/S © 10/2019 All rights reserved. M0010001
33