Hach-Lange RTC103 N-Module - Manual (Page 51)

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Parameterization and operation
4.11.8 MIN RETURN SLUDGE
Minimum return sludge flow rate according to measurement
signal corresponding to 0/4mA.
4.11.9 MAX RETURN SLUDGE
Maximum return sludge flow rate of influent according to
measurement signal corresponding to 20mA.
4.11.10 0/4 to 20mA
Transfer range of 0/4 to 20mA current loop as set in connected
flow measuring instrument.
4.11.11 Q RETURN RATIO
If the value Q RETURN RATIO is “0” the RAS flow is calculated
bases on the mA input signal. If the value is different from “0” the
RAS flow is calculated from the inflow:

Q RETURN = Q RETURN RATIO * INFLOW 
within the limits of MIN RETURN SLUDGE and MAX RETURN
SLUDGE.
4.12 OUTPUTS
4.12.1 MIN DO SETTING (only for option without DO control)
Minimum DO set point corresponding to 0/4mA.
4.12.2 MAX DO SETTING (only for option without DO control)
Maximum DO set point corresponding to 20mA.
4.12.3 0/4 to 20mA
Transfer range of 0/4 to 20mA current loop
• without DO control: for DO setpoint signal.
• with VFD DO control: for VFD blowers signal.
4.13 Volume
4.13.1 Aerated volume
Size of aerated basin (or zone) in m 3 .
4.14 MODBUS
4.14.1 ADDRESS
Start address of an RTC within the modbus network.
4.14.2 DATAORDER
Specifies the register order within a double word.
Presetting: NORMAL