Xylem HV 1.1 - 1.2 - Manual (Page 48)

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increase of the required value after starting of the following pumps (see attached
application example in chapter 13.7.2)
Press Î on the controller to change to
13.7.2 Fall Value
For scaling the required value for 1 to 4 pumps
Actu. Value Dec.
0.15 bar
Adjustable between 0 and 2,5 bar.
This value determines the start value of the 2
nd and the
other following pumps. (Start-Value = REQUIRED VALUE – ACT. VALUE DEC.)
Application example:
1) Pump 1 reaches f
max
(maximum speed )
2) Pressure falls and reaches the start-value of the 2 nd pump
(= REQUIRED VALUE – ACTU. VALUE DEC.)
3) Pump 2 is switched on automatically
4) The required value is calculated new, after the start of the 2
nd pump in the
following way!
New required value = REQUIRED VALUE – ACTU. VALUE DEC. + ACU. VALUE INC.
Generally:
k ... Number of active pumps (k >1)
P = P
set
+ (k-1)*[lift value – fall value]
• Lift value = Fall value ⇒ Pressure constant when pumps switch on
• Lift value > Fall value ⇒ Pressure rises when lag-pump switches on
• Lift value < Fall value ⇒ Pressure falls when lag-pump switches on
Press Î on the controller to change to
13.7.3 Release – Follow up pump
Enable Seq. Ctl.
48.0 Hz
The follow-up pump only starts, when the start-
value is reached (see chapter 13.7.2) and the lead