Hach-Lange RTC103 N-Module - Manual (Page 50)

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Parameterization and operation
4.10.5 SUBST AERATION
If the oxygen sensor (e.g. LDO) signals a fault, the set aeration
stage is selected (stages 1 to 6).
4.10.6 NUMBER OF STAGES
Number of controlled aeration stages (maximum 6).
4.10.7 VFD P MIN (For DO control without VFD option this is fixed to 100%)
Set minimum speed [%] for VFD controlled blowers.
4.11 INPUTS
There are available two mA input connector for each channel.
The first is the flowrate signal (inlet or effluent of plant or lane).
The second is for the recirculation flow rate or the return sludge
flow rate, depending on which is available and not travelled in
ratio to the inlet/outlet flow rate.
4.11.1 MIN INFLOW
Minimum flow rate of influent according to measurement signal
corresponding to 0/4mA
4.11.2 MAX INFLOW
Maximum flow rate of influent according to measurement signal
corresponding to 20mA
4.11.3 0/4 to 20mA
Transfer range of 0/4 to 20mA current loop as set in connected
flow measuring instrument.
4.11.4 MIN RECIRCULATION
Minimum recirculation flow rate according to measurement signal
corresponding to 0/4mA.
4.11.5 MAX RECIRCULATION
Maximum recirculation flow rate of influent according to
measurement signal corresponding to 20mA.
4.11.6 0/4 to 20mA
Transfer range of 0/4 to 20mA current loop as set in connected
flow measuring instrument.
4.11.7 Q RECI RATIO
If the value Q RECI RATIO is “0” the RECI flow is calculated
bases on the mA input signal. If the value is different from “0” the
RECI flow is calculated from the inflow:

Q RECI= Q RECI RATIO * INFLOW 
within the limits of MIN RECIRCULATION and MAX
RECIRCULATION.