Grundfos Control MPC-Serie Installationsanleitung Seite 41

8.7.20 Pump start and stop speed (4.2.8)
Description
The function controls the starting and stopping of pumps. There
are two options:
1. Use calculated speedThis function ensures that the optimum
number of pumps is always running at a desired duty point, in
terms of energy consumption. CU 352 calculates the required
number of pumps and their speed. This requires that the
differential pressure of the pump is measured by a differential-
pressure sensor or separate pressure sensors on the inlet and
outlet side. If calculated speed has been selected, CU 352
ignores the percentages set.
2. Use fixed speedThe pumps are started and stopped at speeds
set by the user.
1. Use calculated speed
Fig. 59 Use calculated speed
Setting via the operating panel
• Settings > Pump cascade control > Pump start and stop speed
> Use calculated speed.
2. Use fixed speed
Fig. 60 Use fixed speed
Setting via the operating panel
• Settings > Pump cascade control > Pump start and stop
speed.
• Select: Use fixed speed.
• Set: Start next pump at this speed > 1 -> 2.
1. Set the speed as percentage.
2. Set the other pumps in the same way.
3. Select: Instant pump stop at > 1 -> 0.
4. Set the speed as percentage.
5. Set the other pumps in the same way.
Factory setting
The function is set to calculated speed.
8.7.21 Min. performance (4.2.9)
Fig. 61 Min. performance
Description
The function ensures circulation in a system. Note that the stop
function, if enabled, can influence this function. See section
8.7.24 Stop function (4.3.1). Examples:
• If zero pumps have been selected, the stop function can stop
the pump if there is no or a very small consumption.
• If pumps have been selected, the stop function will not be
active.
Setting via the operating panel
• Settings > Pump cascade control > Min. performance.
1. Set:
• Number of pumps
• Speed.
Factory setting
The number of pumps is set to zero. The speed in closed loop is
set to 25 %.
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