Grundfos Control MPC Montage- Und Betriebsanleitung Seite 42

8.6.20 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 speed
This 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 speed
The pumps are started and stopped at speeds set by the user.
1. Use calculated speed
Use calculated speed
Setting via the operating panel
• Settings > Pump cascade control > Pump start and stop
speed > Use calculated speed.
2. Use fixed speed
Use fixed speed
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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.
a. Set the speed as percentage.
b. Set the other pumps in the same way.
c. Select: Instant pump stop at > 1 -> 0.
d. Set the speed as percentage.
e. Set the other pumps in the same way.
Factory settings
The function is set to calculated speed.
8.6.21 Min. performance (4.2.9)
Min. performance
Description
The function ensures circulation in a system. Note that the stop
function, if enabled, can influence this function. See section 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 settings
The number of pumps is set to zero. The speed in closed loop is set
to 25 %.
Related information
8.6.24 Stop function (4.3.1)