Endress+Hauser Liquisys M CCM223 - Current Input

Liquisys M CCM223/253 Commissioning
Endress+Hauser 47
Calibration of the complete measuring system makes sense only up to a pH value of the
medium of 8 or 8.2.
Sensor pH value HOCl content Uncompensated value Compensated value
CCS141 8.2 15 % 12 nA 80 nA
CCS140 8 20 % 4 nA 20 nA
Above these pH values, the total error of the measuring system is unacceptably high.
7.4.3 Current input
For the "Current input" function group, you require a relay card with a current input which
is not available in the basic device version. With this function group, you can monitor
process parameters and use them for feedforward control. For this purpose, you must
connect the current output of an external measured variable (e.g. flowmeter) to the 4 to
20mA input of the transmitter. The following assignment applies:
Flow in main stream Current signal in mA Current input signal in %
Flowmeter start of measuring range 4 0
Flowmeter end of measuring range 20 100
Flow monitoring in the main stream
This arrangement is particularly practical if the sample flow through the CCA250 assembly
is completely independent of the flow in the main stream.
This permits signaling of an alarm condition in the main stream (flow too low or has
completely stopped) and triggers dosing switch-off even if the medium flow is maintained
due to the method of installation.
This monitoring method corresponds to monitoring the flow rate in the sample stream
(see SETUP 1).
0
1
1
1
1
0
0
0
A
B
C
D
E
F
G
Z2
Z2
Z3
Z3
A0002019
 32 Alarm signaling and dosing switch-off by the main stream
A Flow in main stream F Flow alarm
B Relay contacts of PID controller G Flow restoration