Danfoss VLT series Programming Manual Download

Page: 183 / 241

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.

25-43 Destaging Threshold

Range:

Function:

Size
related

[ 0
- 100
%]

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

4-11 Motor Speed Low Limit [RPM]

4-12 Motor Speed Low Limit [Hz]

, to the

4-13 Motor Speed High Limit [RPM]

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

0 1

Seconds

Variable speed

pump

Fixed speed

pump

Motor speed

high limit

Destaging

speed

Motor speed

low limit

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.

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

25-42 Staging Threshold

and

4-13 Motor Speed High Limit [RPM]

Staging Speed is calculated with the following
formula:

STAGE = HIGH STAGE%

100

25-44 Staging Speed [RPM]

Range:

Function:

where n

HIGH

is Motor Speed High Limit and

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

25-42 Staging Threshold

, and

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

[0 - 0
RPM]

Readout of the below calculated value for
Destaging Speed. 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. Destaging Speed is
calculated based on

25-43 Destaging Threshold

and

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