Compensation For Pump Startup Time (4.2.10) - Grundfos Control DDD Montage- Und Betriebsanleitung

8.7.18 Pump stop attempt (4.2.7)
Fig. 66 Pump stop attempt
Description
The function makes it possible to set automatic stop attempts of a
pump when several pumps are running. It ensures that the
optimum number of pumps is always running, in terms of energy
consumption. See section 8.7.19 Pump start and stop speed
(4.2.8).
At the same time, the purpose is to avoid disturbances in
connection with automatic stop of pumps.
Stop attempts can either take place with a fixed interval set under
"Interval between stop attempts" or by self-learning. If self-
learning is selected, the interval between stop attempts will be
increased if repeated attempts to stop the pump fail.
Setting via operating panel
• Settings > Pump cascade control > Pump stop attempt.
1. Select: "Self-learning" or "Fixed interval".
2. Set "Interval between stop attempts" if you select "Fixed
interval".
3. Select: Enabled.
Factory setting
The function is enabled, and "Self-learning" is selected.
8.7.19 Pump start and stop speed (4.2.8)
Fig. 67 Pump start and stop speed
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 354 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 354 will ignore the
percentages set.
Setting via operating panel
• Settings > Pump cascade control > Pump start and stop speed
> Use calculated speed.
2. Use fixed speed
The pumps are started and stopped at speeds set by the user.
Setting via operating panel
• Settings > Pump cascade control > Pump start and stop
speed.
1. Select: Use fixed speed.
2. Set: Start next pump at this speed > 1 -> 2.
3. Set the speed as percentage.
4. Set the other pumps in the same way.
5. Select: Instant pump stop at > 1 -> 0.
6. Set the speed as percentage.
7. Set the other pumps in the same way.
Factory setting
The function is set to calculated speed.

8.7.20 Compensation for pump startup time (4.2.10)

Fig. 68 Compensation for pump startup time
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