Customised Settings; Soft Pressure Build-Up; Filling And Pressure Build-Up Phases - Grundfos Control MPC Installation And Operating Instructions Manual

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
Note
for gradient.
Example 1: Increasing the stop limit, Qmin (high flow limit)
• Increase the delta pressure for gradient.
• Reduce the delta time for gradient (pump stopped).
• Reduce the 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 the delta pressure for gradient.
• Increase the delta time for gradient (pump stopped).
• Increase the 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
Note The stop limit depends on the tank size.
System with flow switch
Make the following additional settings:
1. Select: Go to setting of digital input.
Display Digital inputs (4.3.7) appears.
2. Select the digital input where the flow switch is connected.
3. Select: Flow switch.
4. .
Note An open contact indicates low flow.
System with flowmeter
Make the following additional settings:
1. Select: Go to setting of analog input.
Display Analog inputs (4.3.8) appears.
2. Select the analog input where the flowmeter is connected.
3. Select: Flow rate.
4. x 2.
5. Set: Stop limit.
Factory setting
The function is enabled in pressure-boosting applications with the
settings in the table.
Start/stop band:
Min. flow rate:
Distribution above setpoint:
The function is disabled in all other applications.

8.7.24 Soft pressure build-up (4.3.3)

Value
6 %
1.5 seconds
2.0 seconds
Fig. 69 Soft pressure build-up
10 %
Description
This function is typically used in pressure-boosting applications
and ensures a smooth start-up of systems with for instance empty
pipes.
Start-up takes place in two phases. See fig. 70.
1. Filling phase
The pipework is slowly filled with water. When the pressure
sensor of the system detects that the pipework has been
Value filled, phase two begins.
2. Pressure build-up phase
3 %
The system pressure is increased until the setpoint is
15.0 seconds
reached. The pressure build-up takes place over a ramp time.
25.0 seconds
If the setpoint is not reached within a given time, a warning or
an alarm can be given, and the pumps can be stopped at the
6 %
same time.
H [m]
Fig. 70 Filling and pressure build-up phases
25 %
30 % of the rated flow rate of
one pump
50 %
1. Filling phase 2. Pressure build-up phase
Filling time Ramp time
Time [sec]
39