The “PmpSequenceGen” function block is used. The following functions are included:
-
Decides which pump is ready to run in the auto mode.
-
Decides which pump to start in the sequence, based on the least actual runtime hours.
Exception – when the pump station is traditional type (with master pump on VFD, rest on DOL), then the pump ID = 1 which is attached to the VFD will always run as master and is first to start and last to stop.
-
Decides which pump to stop in the sequence, based on the highest actual runtime hours.
Exception – when the pump station is traditional type (with master pump on VFD, rest on DOL), then the pump ID = 1 which is attached to the VFD will always run as master and is first to start and last to stop.
-
Assigns a master status to the pump in the sequence.
-
Indicates how many pumps are ready for automation and how many are running.
The table below explains a use case where the demand increases and then decreases. The sequence is generated based on these criteria by the function block “PmpSequenceGen”.
|
Demand |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Master |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
|
Next Pump to Start |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
2 |
Whichever pump has minimum run time will start next |
||||||
|
Next Pump to Stop |
1 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
1 |
|
Pumps Running |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
|
|
2 |
2 |
2 |
2 |
2 |
2 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
|||
|
3 |
3 |
3 |
3 |
3 |
3 |
4 |
5 |
6 |
7 |
8 |
|||||
|
4 |
4 |
4 |
4 |
4 |
5 |
6 |
7 |
8 |
|||||||
|
5 |
5 |
5 |
5 |
6 |
7 |
8 |
|||||||||
|
6 |
6 |
6 |
7 |
8 |
|||||||||||
|
7 |
7 |
8 |
|||||||||||||
|
8 |
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