Danfoss VLT FC 100 Series Programming Manual page 194

Parameter Description
Figure 3.77
NOTE!
If the setpoint is reached after staging before the variable-
speed pump reaches its minimum speed, the system will
enter the closed-loop state as soon as the feedback
pressure crosses the setpoint.
25-43 De-staging Threshold
Range: Function:
Size [ 0 - When removing a fixed-speed pump, in order to
related 100 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 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.
De-staging Threshold must range from
LOW
STAGE % =
HIGH
is Motor Speed Low Limit and n
Speed High Limit.
Figure 3.78
®
VLT HVAC Drive Programming Guide
to 100%, where n
× 100 %
LOW
is Motor
HIGH
MG11CD22 - VLT ® is a registered Danfoss trademark
NOTE!
If the setpoint is reached after staging before the variable-
speed pump reaches its maximum speed, the system will
enter the closed-loop state as soon as the feedback
pressure crosses the setpoint.
25-44 Staging Speed [RPM]
Range: Function:
0 [0 - 0 Readout of the value calculated below for
RPM RPM] Staging Speed When adding a fixed-speed
*
pump, in order 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. Staging Speed
calculation is based on 25-42 Staging Threshold,
and 4-13 Motor Speed High Limit [RPM].
Staging Speed is calculated with the following
formula:
STAGE = HIGH
where n is Motor Speed High Limit and
HIGH
n is the value of Staging Threshold.
STAGE100%
25-45 Staging Speed [Hz]
Range: Function:
0.0 [0.0 Readout of the value calculated below for Staging
Hz - 0.0 Speed When adding a fixed-speed pump, in order
*
Hz] 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.
Staging Speed calculation is based on
25-42 Staging Threshold, and 4-14 Motor Speed High
Limit [Hz].
Staging Speed is calculated with the following
formula:
STAGE %
STAGE = HIGH
100
High Limit and n
Threshold.
STAGE %
100
where n is Motor Speed
HIGH
is the value of Staging
STAGE100%
3-167
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