ZFC
ZFC K03/0522
page 21
7.1.11
EXPLANATION OF SETUP-MENU A - ANALOG OUTPUT
A linear 4-20 mA signal (option AB: 0-20 mA or option AU: 0-10 V) output signal is
generated that represents the flow rate. The settings for the flow rate influence the
analog output directly. The relationship between the flow rate and the analog output is
set with the following settings.
A
ANALOG OUTPUT
A1
output
If the analog output is not used, select disable to minimize the power
consumption.
Option 4T: When a power supply is available but the output is
disabled, a 3.5mA signal will be generated.
A2 rate-min
Enter here the flow rate at which the output should generate the minimum signal
4mA - in most applications at zero flow. The number of decimals shown
depends upon setup 23. The engineering units/time (e.g. L/min) is dependent
upon setup 21 and 22.
A3 rate-max
Enter here the flow rate at which the output should generate the maximum signal
(20 mA) - in most applications at maximum flow. The number of decimals shown
depends upon setup 23. The engineering units/time (e.g. L/min) is dependent
upon setup 21 and 22.
A4 cut-off
To ignore leakage of the flow for example, a low flow cut-off can be set as a
percentage of the full range of 16 mA, 20 mA.
When the flow is less than the required rate, the current will be the minimum
signal 4 mA.
Example: Calculate the cut-off.
Rate-min: 0L/min [4mA], Rate-max: 100 L/min [16mA], Cut-off: 2%
Required rate [L/min]: (rate-max - rate-min)*cut-off: (100-0)*2%=2.0L/min
Output [mA]: rate-min + (rate-max*cut-off): 4+(16*2%)=4.32mA
A5 tune-min
The 4mA value can be tuned precisely with this setting. The initial minimum
analog output value is 4mA. However, this value might differ slightly due to
ambient influences such as temperature for example.
Before tuning the signal, make sure that the analog signal is idle (not used)
for any application!
After pressing PROG, the current will be about 4mA. The current can be
increased / decreased with the arrow keys and is directly active. Press
ENTER to store the new value.
If required, you can program the analog output 'up-side-down'. The
4mA
represents the maximum flow rate and the 20mA represents the minimum flow
rate.
