Danfoss VLT FC 100 Series Programming Manual page 167

Parameter Description
22-76 Interval between Starts
Range:
Size related
*
3 3
- 3600 s]
22-77 Minimum Run Time
Range:
0 s [ 0 - par.
*
22-76 s]
NOTE!
Does not work in cascade mode.
3.20.7 22-8* Flow Compensation
It is sometimes the case that it is not possible for a
pressure transducer to be placed at a remote point in the
system and it can only be located close to the fan/pump
outlet. Flow compensation operates by adjusting the
setpoint according to the output frequency, which is
almost proportional to flow, thus compensating for higher
losses at higher flow rates.
H (Required pressure) is the setpoint for closed-loop
DESIGN
(PI) operation of the Adjustable frequency drive and is set
as for closed-loop operation without flow compensation.
It is recommended to use slip compensation and RPM as
unit.
3-140
Function:
[ par. 22-77 Sets the time desired as minimum
time between two starts. Any
normal start command (Start/Jog/
Freeze) will be disregarded until the
timer has expired.
Function:
Sets the time desired as minimum run time
after a normal start command (Start/Jog/
Freeze). Any normal stop command will be
disregarded until the set time has expired. The
timer will start counting following a normal
start command (Start/Jog/Freeze).
The timer will be overridden by a Coast
(Inverse) or an External Interlock command.
MG11CD22 - VLT
®
VLT HVAC Drive Programming Guide
Figure 3.54
NOTE!
When flow compensation is used with the Cascade
Controller (parameter group 25-**), the actual setpoint will
not depend on speed (flow) but on the number of pumps
cut in. See below:
Figure 3.55
There are two methods which can be employed,
depending upon whether or not the Speed at System
design Working Point is known.
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