Grundfos CU 301 User Manual

5
1. Constant-pressure control
The control unit CU 301 is for use only with Grundfos
SQE pumps incorporating electronic power factor
correction (PFC).
1.1 Description
The system maintains a constant pressure within the
maximum pump performance in spite of a varying
water consumption.
The CU 301 is designed for wall mounting only.
Fig. 1 Example of a system with constant-
pressure control
1.2 Function
The pressure is registered by means of the pressure
sensor, which transmits a 4-20 mA signal to the
CU 301. The CU 301 adjusts the pump performance
accordingly to maintain constant pressure by chang-
ing the pump speed.
Mains borne signalling
The communication between the CU 301 and the
pump is via the power supply cable.
This communication principle is mains borne signal-
ling (or power line communication). Using this princi-
ple means that no additional cables to the pump are
required.
The communication of data is effected via a high-fre-
quency signal transmitted to the power supply cable
and led into the electronics unit by means of signal
coils incorporated in the motor and the CU 301
respectively.
In situations where multiple CU 301 pump power
cables are run parallel in wiring trays or conduit and
less than 10-12 inches apart, the possibility for
undesired communication between units exists.
When this occurs, intermittent or continuous
"No contact" is typically seen. Other unexpected
errors may also be seen.
Refer to section 5.3.10 for further instructions.
Fig. 2 Principle of mains borne signalling
TM01 7862 4999
Pos. Description
1 CU 301
2 Diaphragm tank (2 gal.)
3 Pressure sensor
4 SQE pump
1
4
2
3
TM01 8495 1606
Pos. Description
1 Supply to the electronics
2 Signal coils
3 Capacitor
4
Electronics for the control of
the communication
5 On/Off button
6 Sensor signal
7 Mains supply
8 Communication signals
R 100
CU 301
1
5
2
4
3
6
7
8
CU 301

Grundfos CU 301 Specifications

General

Brand	Grundfos
Model	CU 301
Category	Water Pump
Language	English