Danfoss VLT Programming Guide

25-43 Destaging Threshold
Range: Function:
Application
dependent*
[Application dependant] 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 “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 par. 4-11
Motor Speed Low Limit [RPM] or par. 4-12 Motor
Speed Low Limit [Hz]
, to the par. 4-13 Motor Speed High Limit [RPM] or par. 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.
NB!
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.
25-44 Staging Speed [RPM]
Range: Function:
0 RPM* [0 - 0 RPM] Readout of the below calculated value for 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 par. 25-42
Staging Threshold , and par. 4-13 Motor Speed High Limit
[RPM]
.
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.
25-45 Staging Speed [Hz]
Range: Function:
0.0 Hz* [0.0 - 0.0 Hz] Readout of the below calculated value for 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 par. 25-42
Staging Threshold , and par. 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.
VLT
®
HVAC Drive Programming Guide 3 Parameter Description
MG.11.C9.02 - VLT
®
is a registered Danfoss trademark 247
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)