Hach-Lange RTC112 SD-Module - Manual (Page 34)

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Parameterization and operation
4.9.6 0/4...20 mA
Transfer range of the 0/4 to 20 mA current loop (as set in
connected flow measuring instrument).
4.10 OUTPUTS
4.10.1 MIN FEED FLOW
Minimum feed flow rate [m³/h] in accordance with 0/4 mA.
4.10.2 MAX FEED FLOW
Maximum feed flow rate [m³/h] in accordance with 20 mA.
4.10.3 0/4...20 mA
Transfer range of 0/4 to 20 mA current loop (as set in connected
flow measuring instrument).
4.10.4 MIN POLYMER FLOW
Minimum polymer pump delivery rate in accordance with 0/4 mA.
4.10.5 MAX POLYMER FLOW
Maximum polymer pump delivery rate in accordance with 20 mA.
4.10.6 0/4...20 mA
Transfer range of 0/4 to 20 mA current loop (as set in connected
flow measuring instrument).
4.10.7 CONTROL CYCLE
Pulse/pause mode for the polymer pump open-loop control for
dosing rates beneath the minimum polymer flow rate (MIN
POLYMER FLOW). The on/off duration in pulse/pause mode can
be affected by the duration of the CONTROL CYCLE. For
example, with a CONTROL CYCLE of 100 seconds and a dosing
control value of 60 %, the polymer pump is switched on for
60 seconds and switched off for 40 seconds. Short cycle times
increase the switching frequency but enable more precise
adaptation to individual requirements.
Note: CONTROL CYCLE must be divisible by MIN RUNTIME and
produce a whole number.
4.10.8 MIN RUNTIME
Minimum ON time in pulse/pause dosing mode. The pump is
activated for this runtime at the very least. The MIN RUNTIME
must be shorter than the duration of the CONTROL CYCLE.
4.11 Displayed measurement values and variables
The following measurement values and variables are shown on
the sc1000 display and transferred via fieldbus (refer to
section Appendix B ).