Parameter Default Description
MODBUS baudrate
XXXXX
9600 MODBUS baudrate from 1200 bps to 57600 bps
MODBUS data format
XXXXX
RTU
N81
MODBUS data format: RTU N81, RTU N82, RTU E81, RTU O81
MODBUS EEPROM
write
ON/OFF
OFF Setting the writing mode of the parameters transmitted via MODBUS:
ON: the datum is saved in EEPROM
OFF: the datum is not saved in EEPROM
Change password1
Press ENT
By pressing the ENT key it is possible to change the installer level password (level 1) (default 001).
10. Constant pressure operation
10.1. Introduction
TheMIDA can manage the running speed of the pump in such a way as to keep the pressure constant as the water
demand changes. A pressure sensor placed as close as possible to the pump is used for this purpose.
1: Inverter; 2: Pump; 3: Check valve; 4: Pressure vessel; 5: Gate valve; 6: Gate valve; 7: Pressure sensor
10.2. The pressure vessel
In water systems equipped with inverters, the function of the pressure vessel is to compensate for losses (or
minimum water consumption) and maintain pressure when the pump is stopped, thus avoiding excessively frequent
start/stop cycles. It is of fundamental importance to correctly choose the volume and the pre-charge pressure of the
pressure vessel. Too small volumes do not allow effectively compensating the minimum water consumption or the
losses when the pump is stopped, while too high volumes make it difficult for the inverter to control the pressure.
It is generally sufficient to place a pressure vessel with a volume of about 10% of the maximum flow rate required,
considered in liters/minute.
Example
If the maximum flow rate required is 60 l/min, it is sufficient to use a 6 liter pressure vessel.
The pre-charge pressure of the pressure vessel must be approx. 80% of the operating pressure.
Example
If the set pressure in the inverter is 4 bar, the pre-charge pressure of the pressure vessel should be approx. 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 feeds the analog inputs.
The pressure sensor is connected via the terminals of the analogue input 1, i.e:
MIDA
39
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