Sulzer ABS PC 441 - Page 41

81307063I
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Example 2 Temporary high inflow.
Startlevelpump1=2.0m
Startlevelpump2=3.0m
Stoplevelpump1=1.0m
Stoplevelpump2=1.5m
Method used: Alt. each pump stops Alt. when all pumps stop
Pit level increase
At level 2.0 m Pump 1 start
Pump 1 start
At level 3.0 m Pump 2 start Pump 2 start
Pit level decrease
At level 1.5 m Pump 2 stop Pump 2 stop
At level 1.0 m Pump 1 stop Pump 1 stop
Pit level increase
At level 2.0 m Pump 1 start
Pump 2 start
At level 3.0 m Pump 2 start Pump 1 start
Pit level decrease
At level 1.5 m Pump 2 stop Pump 1 stop
At level 1.0 m Pump 1 stop Pump 2 stop
Ifalternateeachpumpsstopmethodisused,pump1alwaysstartsrst.
2. Asymmetrical alternation
Thedi󰀨erencebetweenasymmetricalandnormalalternationisthatthepumpsaredividedintotwoalter-
natinggroups,primaryandsecondarygroup.Withineachgroupthepumpsarealternatingasinnormal
alternation.
Normallypumpsinprimarygroupstartrst.Afteraadjustablenumberofpumpstopsinprimarygroup
pumpsinthesecondarygroupstartrst.Thestopcounterresetsandatnextpumpcycleprimarypumps
startrstagain.Ifthepumpsintheprimarygroupdonothavethecapacitytopumpdownandthepitlevel
continuestoincrease,thepumpsinthesecondarywillstartindependentofthestopcounter.
• Pumpsdividedintwoalternationgroups,primaryandsecondary.
• A group can have 1 to 3 pumps within.
• Adjustablenumberofstartsinprimarygroupbeforesecondarygroupstart.
Example:
Primarygroupcontainspump1–3,andstartstwicebeforesecondarygroupstartswhichonlycontainspump
number 4.
Function:
• Uneven running times
• Jog runs of spare pump
• Runpumpsthathasatendencytoblockmoreoften