Xylem LOWARA e-SVE - Example: Effective Required Value

en – Original instructions
45
R2
 P29 (Ramp 2) - speed ramp fast decrease
R3
 P30 (Ramp 3) - speed ramp slow increase
R4
 P31 (Ramp 4) - speed ramp slow decrease
For further information about Ramps adjustment, see. par. 7.5.3.
9.3 Example: Effective Required Value
Pumps activation in cascade modes:
1. Lead pump reaches its P60 (Enable Speed).
2. Actual value falls to the cut in-value of the 1st assist pump.
The 1st assist pump switches on automatically. (Cut in-value = P01 (Required Value) - P59
(Actual Value Decrease))
3. A new required value, P02 (Effective Required Value) is calculated after the start up.
Calculation of Effective Required Value in Cascade Serial (MSE):
K = number of active pumps (k > 1)
Pr = pump priority
 If K - Pr > 0
P02 (Effective Required Value) = P01 (Required Value) + (K–Pr) * P58 (Actual Value Increase
 If K - Pr = 0
P02 (Effective Required Value) = P01 (Required Value) + P58 (Actual Value Increase) - P59
(Actual Value Decrease)
Calculation of Effective Required Value in Cascade Synchronous (MSY):
K = number of active pumps (k > 1)
 If K > 1
P02 (Effective Required Value) = P01 (Required Value) + (K–1) * P58 (Actual Value Increase
 If K = 1
P02 (Effective Required Value) = P01 (Required Value) + P58 (Actual Value Increase) - P59
(Actual Value Decrease)
Behavior of P58 (Actual Value Increase) and P59 (Actual Value Decrease):
 if P58 (Actual Value Increase) = P59 (Actual Value Decrease) → Pressure constant,
independent of how many pumps are in operation.
 if P58 (Actual Value Increase) > P59 (Actual Value Decrease) → Pressure rises when assist
pump switches on.
 if P58 (Actual Value Increase) < P59 (Actual Value Decrease) → Pressure falls when assist
pump switches on.