Danfoss VLT AQUA Drive FC 200 Programming Manual page 171

Parameter Description
Speed
3 3
Cascade Controller
prepares for
removing pump
Illustration 3.75 Destaging
25-42 Staging Threshold
Range:
Size [ 0
related - 100
*
%]
170
VLT
Destaging
Lead pump
(controlled by freq. conv.)
Fixed speed pump
(controlled by soft starter)
t
2
P 25-41
Lead pump starts
to ramp up
Function:
When adding a fixed 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 fixed speed pump is staged on. The
Staging Threshold is used to calculate the speed
of the variable speed pump when the "cut-in
point" of the fixed speed pump occurs. The
calculation of the Staging Threshold is the ratio
of 4-11 Motor Speed Low Limit [RPM] or
4-12 Motor Speed Low Limit [Hz], to the
4-13 Motor Speed High Limit [RPM] or 4-14 Motor
Speed High Limit [Hz], expressed in percent.
Staging Threshold must range from
LOW
= × 100 %
HIGH
STAGE %
to 100%, where n is Motor Speed Low Limit
LOW
and n is Motor Speed High Limit.
HIGH
MG20O602 - VLT
®
AQUA Drive Programming Guide
Motor speed
high limit
Staging speed
Motor speed
low limit
Illustration 3.76
NOTE
If the set-point is reached after staging before the variable
speed pump reaches its minimum speed - the system will
enter the state closed loop as soon as the feedback
pressure is crossing the set-point.
Time
25-43 Destaging Threshold
Range:
Size
related - 100
*
%]
Motor speed
high limit
Destaging
speed
Motor speed
low limit
Illustration 3.77
NOTE
If the set-point is reached after staging before the variable
speed pump reaches its maximum speed - the system will
enter the state closed loop as soon as the feedback
pressure is crossing the set-point.
®
is a registered Danfoss trademark
0 4 5
Function:
[ 0 When removing a fixed 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 fixed speed pump is destaged. The
Destaging Threshold is used to calculate the
speed of the variable speed pump when the
destaging of the fixed speed pump occurs. The
calculation of the Destaging Threshold is the
ratio of 4-11 Motor Speed Low Limit [RPM] or
4-12 Motor Speed Low Limit [Hz], to the
4-13 Motor Speed High Limit [RPM] or 4-14 Motor
Speed High Limit [Hz], expressed in percent.
Destaging Threshold must range from
LOW
to 100%, where n
STAGE % =
× 100 %
HIGH
is Motor Speed Low Limit and n
Speed High Limit.
Fixed speed
pump
0 1 3 5
Fixed speed
pump
Variable speed
pump
Seconds
LOW
is Motor
HIGH
Variable speed
pump
Seconds