If the set pressure in the inverter is 4 bar, the pre-charge pressure of the pressure tank should be ap-
prox. 3.2 bar.
NOTE
The pre-charge pressure must be adjusted with the system completely unloaded.
10.3. Electrical connections
The device may be connected to linear pressure sensors with 4 - 20 mA output. The supply voltage
range of the sensor must be such as to include the 15 V DC voltage with which the device supplies the
analog inputs.
The pressure sensor is connected via the terminals of the analogue input 1, i.e:
• AN1: 4-20 mA signal (-)
• +15V: 15 VDC power supply (+)
The device supports the installation of a second pressure sensor for:
• Operation at constant differential pressure (read the dedicated chapter).
• Automatic replacement of the main pressure sensor in case of failure.
• Exchange of active pressure sensor via digital input.
The connection of the secondary pressure sensor is made via the terminals of the analogue input 2 or:
• AN2: 4-20 mA signal (-)
• +15V: 15 VDC power supply (+)
11. Fractioning of the pumping system
11.1. Introduction.
When the variation in water demand is considerable, it is a good idea to fraction the pumping unit into
several units to ensure greater efficiency and reliability.
A fractioning method (called COMBO mode) consists in using several pumps in parallel (up to 8) each
controlled by an inverter.
In this case, the efficiency and reliability of the pumping unit is maximised, ensuring soft starts and
stops and complete protection of the pumps. The alternation of operation also allows to uniform the
wear of the pumps and, in case of failure of a pump or an inverter, the remaining units of the group can
continue their operation.
PSDrive
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