Grundfos Control MPC-Serie Installationsanleitung Seite 44

Setting range
Start/stop band: 5-30 %
2-50 % of the rated flow rate (Qnom) of
one of the pumps. (It can only be set if
Minimum flow rate:
direct flow measurement by means of
flowmeter has been selected.)
Distribution above
0-100 %.
setpoint:
Setting via the operating panel
System without flow switch or flowmeter
• Settings > Secondary functions > Stop function.
• Select: Enabled.
1. Set: Start/stop band.
2. Select: Go to setting of flow stop parameters.
Fig. 67 Stop parameters
3. Select one of the stop parameters. If you select "Customised
settings", you must set the parameters shown in fig. 68. See
the examples below.
Fig. 68 Customised settings
Rule of thumb: Speed reduction = 2 x delta pressure
for gradient.
44
Example 1: Increasing the stop limit, Qmin (high flow limit)
• Increase "Delta pressure for gradient".
• Reduce "Delta time for gradient (pump stopped)".
• Reduce "Delta time for gradient (pump running)".
• Increase "Speed reduction".
Example of increased stop limit
Parameter
Delta pressure for gradient
Delta time for gradient (pump stopped)
Delta time for gradient (pump running)
Speed reduction
Example 2: Reducing the stop limit, Qmin (low flow limit)
• Reduce "Delta pressure for gradient".
• Increase "Delta time for gradient (pump stopped)".
• Increase "Delta time for gradient (pump running)".
• Reduce "Speed reduction".
Example of reduced flow limit
Parameter
Delta pressure for gradient
Delta time for gradient (pump stopped)
Delta time for gradient (pump running)
Speed reduction
The stop limit depends on the tank size.
Alternative input
If you select "Alternative input", the controller calculates the stop
parameters based on the following inputs:
• system set-point
• total tank volume
• precharge pressure
• desired stop flow.
Fig. 69 Alternative input
Value
6 %
1.5 seconds
2.0 seconds
10 %
Value
3 %
15.0 seconds
25.0 seconds
6 %