The first pump switched on is the first pump to
be switched off, regardless of the set points, so
the setpoints are dynamically changed to enable
this. If a pump fails to meet the demand (due to
malfunction, intake blockage and so on), then it
is stopped, and another pump shall take over.
Each time a pump is required to start then the
pump with the least running hours (with respect
to the service ratio) is started (i.e. the setpoints
are re-assigned accordingly). Each pump has its
own setpoints (P213, 223, 233, 243, 253, 263 &
P214, 224, 234, 244, 254, 264). The third setpoint
(P215, 225, 235, 245, 255, 265) is used to set the
service ratio. E.g., if two pumps A and B have the
service ratio set to 2 and 1 respectively, then
pump A will operate for twice as many hours as
pump B.
The first pump switched on is the first pump to
be switched off, etc. regardless of the set points,
so the setpoints are dynamically changed to
enable this.
When a service ratio duty is being used, on all
other pumps in use, the standby pump can be
started on a ratio basis only, when it will assume
the setpoints of the next pump to start. The third
setpoint (P215, 225, 235, 245, 255, 265) is used
to set the service ratio.
There are four pumps. Two rotate their start-up
sequence with each other. If the two pumps
cannot keep up, the level rise to the setpoints of
the other two pumps which take over and rotate
their sequence with each other.
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