Danfoss VLT FC 102 Programming Manual page 247

Parameter Descriptions
25-56 Staging Mode at Alternation
Option: Function:
This parameter is only active if the
option selected in
parameter 25-50 Lead Pump
Alternation is different from [0] Off.
2 types of staging and destaging of
pumps are possible. Slow transfer
makes staging and destaging
smooth. Quick transfer makes
staging and destaging as fast as
possible; the variable-speed pump
is just cut out (coasted).
[0] Slow At alternation, the variable-speed
*
pump is ramped up to maximum
speed and then ramped down to a
standstill.
[1] Quick At alternation, the variable-speed
pump is ramped up to maximum
speed and then coasted to
standstill.
Illustration 3.87 is an example of the slow transfer-staging.
The variable-speed pump (top graph) and 1 fixed speed
pump (bottom graph) run before the staging command.
When the [0] Slow transfer command is activated, an
alternation is carried out by ramping the variable- speed
pump to parameter 4-13 Motor Speed High Limit [RPM] or
parameter 4-14 Motor Speed High Limit [Hz], and then
decelerated to zero speed. After a delay before starting
next pump (parameter 25-58 Run Next Pump Delay), the
next lead pump (middle graph) is accelerated and another
original lead pump (top graph) is added after the delay
before running on mains (parameter 25-59 Run on Mains
Delay) as a fixed speed pump. The next lead pump (middle
graph) is decelerated to motor speed low limit and then
allowed to vary speed to maintain system pressure.
M0010001
Programming Guide
Motor speed
high limit
Destaging
speed
Motor speed
low limit
Staging
command
Motor speed
high limit
Staging
speed
Motor speed
low limit
Motor speed
high limit
Destaging
speed
Motor speed
low limit
Illustration 3.87 Staging Mode at Alternation
25-58 Run Next Pump Delay
Range:
0.1 s
*
25-59 Run on Mains Delay
Range:
0.5 s
*
Danfoss A/S © 10/2019 All rights reserved.
Fixed speed
Variable speed
pump
pump
Delay before
Delay
running
before starting
on mains
next pump
Variable speed
pump
Fixed speed
pump
Function:
[0.1 - 5 s] This parameter is only active if the
option selected in
parameter 25-50 Lead Pump
Alternation is different from [0] Off.
This parameter sets the time
between stopping the old variable-
speed pump and starting another
pump as a new variable-speed
pump. Refer to
parameter 25-56 Staging Mode at
Alternation for description of
staging and alternation.
Function:
[ par. 25-58 - This parameter is only active if the
5 s] option selected in
parameter 25-50 Lead Pump
Alternation is different from [0] Off.
This parameter sets the time
between stopping the old variable
speed pump and starting this
pump as a new fixed speed pump.
Refer to Illustration 3.87 for
description of staging and
alternation.
Seconds
3 3
Seconds
Seconds
245