Nastec MIDA 203, Руководство по установке, использованию и техническому обслуживанию

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• AN1: 4-20 mA signal (-)
• +15V: 15 VDC power supply (+)
The device supports the installation of a second pressure sensor for:
• Operating 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 secondary pressure sensor is connected via the terminals of the analogue input 2, i.e:
• AN2: 4-20 mA signal (-)
• +15V: 15 VDC power supply (+)
11. Splitting the pumping system
11.1. Introduction.
When the variation in water demand is considerable, it is a good idea to split the pumping unit into several units to
ensure greater efficiency and reliability.
A splitting 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 maximized, ensuring soft starts and stops and
complete protection of the pumps. The alternation of operation also allows to even out 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.
1
2
3
4
5
6 7
1
2 3 6 7
1
2 3 6 7
1: Inverter; 2: Pump; 3: Check valve; 4: Pressure vessel; 5: Gate valve; 6: Gate valve; 7: Pressure sensor
11.2. Variable speed pumping unit with two or more pumps in COMBO
mode.
The unit consists of two or more pumps (up to 8) each controlled by an inverter, and each equipped with its own
pressure sensor. The inverters are connected to each other via RS485 serial port.
One inverter is configured as master (address 00) whereas the others are configured as slaves (addresses 01 to
07).
NOTE
Each inverter must be equipped with its own pressure sensor.
11.2.1. Cascade operating principle.
Cascade operation is the default operation in COMBO mode.
When water is required, a pump is started at variable speed according to the demand.
As the demand increases and the maximum frequency is reached, a second pump is started.
MIDA
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