Grundfos CU 301 Instrucciones De Instalación Y Operación página 8

3.4 Precharge pressure setting
CU 301 is designed to work with a 2 gal
diaphragm tank.
Set the precharge pressure of the diaphragm tank
to 70 % of the pressure setting in order to use the
tank to the limit of its capacity. This is of course
especially important when the tank volume is
limited to 2 gal.
Use the values in the following table.
Precharge pressure is measured with 0 psi in the
pipeline:
Setting
[psi]
40
50
60
70
80
90
100
If the precharge pressure is higher than the
pressure setting, the system is not able to control
the pressure.
3.5 Pressure relief valve
In order to provide protection against the risk of a
overpressurization, install a pressure relief valve
down stream of the well head. The setpoint of the
pressure relief valve must be at least 30 psi above
the pressure setting. See section
product.
We recommend that the relief valve is plumbed to
an appropriate drainage point.
8
Precharge pressure
[psi]
28
35
42
49
56
63
70
6. Setting the
4. Product introduction
4.1 Product description
The system maintains a constant pressure within
the maximum pump performance despite varying
water consumption.
Figure Example installation
an installation with constant-pressure control.
1
4
Example installation
Pos. Description
1 CU 301
2 Diaphragm tank (2 gal)
3 Pressure sensor
4 SQE pump
The pressure is registered by the pressure
sensor, which transmits a 4-20 mA signal to CU
301. CU 301 adjusts the pump performance
accordingly by changing the pump speed.
Mains borne signalling (power line
communication)
CU 301 and the pump communicate via the power
cable.
This communication principle is called 'mains
borne signalling (power line communication).
Using this principle means that no additional
cables to the pump are required.
The data communication is effected by a high-
frequency signal transmitted to the power cable.
The data is led into the electronics unit by signal
coils incorporated in the motor and CU 301
respectively.
Figure Principle of mains borne signalling (power
line communication) shows the principle of mains
borne signalling (power line communication)
between CU 301 and the pump.
shows an example of
2
3