Danfoss VLT HVAC Drive FC 102, Руководство по программированию, Страница: 196 / 250

25-28 Stage Function Time
Range: Function:
15
s
*
[0 -
300 s] The stage function time is programmed to avoid
frequent staging of the fixed speed pumps. The
stage function time starts if it is
[1] Enabled by
parameter 25-27 Stage Function , and when the
variable speed pump is running at motor speed
high limit,
parameter 4-13 Motor Speed High Limit
[RPM] or parameter 4-14 Motor Speed High Limit [Hz] ,
with at least 1 fixed speed pump in the stop
position. When the programmed value of the timer
expires, a fixed speed pump is staged.
25-29 Destage Function
Option: Function:
The destage function ensures that the lowest
numbers of pumps are running to save energy
and to avoid dead head water circulation in the
variable speed pump. If the destage function is
set to
[0] Disabled , parameter 25-30 Destage
Function Time is not activated.
[0] Disabled
[1]
*
Enabled
25-30 Destage Function Time
Range: Function:
15
s
*
[0 -
300 s] The destage function timer is programmable to
avoid frequent staging/destaging of the fixed speed
pumps. The destage function time starts when the
adjustable speed pump is running at
parameter 4-11 Motor Speed Low Limit [RPM] or
parameter 4-12 Motor Speed Low Limit [Hz] , with 1 or
more fixed speed pumps in operation and system
requirements satisfied. In this situation, the
adjustable speed pump contributes a little to the
system. When the programmed value of the timer
expires, a stage is removed, avoiding dead head
water circulation in the adjustable speed pump.
175ZA640.11
(4-12)
(27-27)
F
min
F VLT pump
De-stage
timer period
Pump
switch-off
Illustration 3.75 Destage Function Time
3.23.3 25-4* Staging Settings
Parameters determining conditions for staging/destaging
the pumps.
25-40 Ramp Down Delay
Range: Function:
10 s
*
[0 -
120 s] When adding a fixed speed pump controlled by
a soft starter or a star-delta starter, it is possible
to delay the ramp down of the lead pump until
a preset time after the start of the fixed speed
pump to eliminate pressure surges or water
hammer in the system.
Use this option only if [1] Soft Starter or [2] Star
Delta is selected in parameter 25-02 Motor Start .
25-41 Ramp Up Delay
Range: Function:
2 s
*
[0 -
12 s] When removing a fixed speed pump controlled by
a soft starter, it is possible to delay the ramp up of
the lead pump until a preset time after the
stopping of the fixed speed pump to eliminate
pressure surges or water hammer in the system.
Only to be used if [1] Soft Starter is selected in
parameter 25-02 Motor Start .
Speed
Time
Fixed speed pump
(controlled by soft starter)
Lead pump starts
to ramp down
Cascade Controller
calls for another
pump
Staging
Lead pump
(controlled by freq. conv.)
t
1
P 25-40
130BC371.10
Illustration 3.76 Staging
Parameter Descriptions
VLT
®
HVAC Drive FC 102
194 Danfoss A/S © 03/2015 All rights reserved. MG11CE02
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