Grundfos Control MPC Montage- Und Betriebsanleitung Seite 45

Y
A
B
2
H
Set
1
On/off operation
Pos. Description
Start: H -0.5 × start/stop band
1
set
Stop: H +0.5 × start/stop band
2
set
A Normal operation
B Pressure boosting
C Stop
X Time [sec]
Y H [m]
The flow rate is estimated by CU 352 when the pump is in the stop
period. As long as the flow rate is lower than Q
in on/off operation. If the flow rate is increased to above Q
pump returns to normal operation, H
setpoint. See section Setpoint (1.2.2).
Detection of low flow rate
Low flow rate can be detected in two ways:
• direct flow measurement with a flowmeter or flow switch
• estimation of flow rate by measurement of pressure and speed.
If the system is not connected to a flowmeter or flow switch, the
stop function will use the estimating function.
If the detection of low flow rate is based on flow estimation, a
diaphragm tank of a certain size and with a certain precharge
pressure is required.
For further information, see the document below. The document is
also available on Grundfos Product Center.
Title QR code Link
http://
Tank calculation
net.grundfos.com/qr/i
in E systems
/92845021
Precharge pressure
Hydro MPC-E, -EC and -F:
During each flow estimation (every 2 minutes), the estimating
function will disturb the outlet pressure by ± 10 % of the setpoint. If
this disturbance is not acceptable, the stop function must be based
on direct flow measurement with a flowmeter or flow switch.
The minimum flow rate can be set, that is the flow rate at which the
system changes to on/off control of the last pump in operation.
If both a flowmeter and a flow switch are connected, the
changeover to on/off control will be determined by the unit first
indicating low flow rate.
Setting range
Start/stop band: 5-30 %
C
C B
X
, the pump runs
min
, the
min
. H is equal to the actual
set set
Publication
number
92845021
0.7 × the setpoint.
2-50 % of the rated flow rate (Q
of the pumps. (It can only be set if direct
Minimum flow rate:
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.
Stop parameters
3. Select one of the stop parameters. If you select Customised
settings, you must set the parameters shown as in the
examples below.
Customised settings
Rule of thumb: Speed reduction = 2 × delta pressure for
gradient.
) of one
nom
45