Foxcroft FX-300-F, Инструкция по эксплуатации

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39
Typical Installation Wiring
Figure 12
Note : An alternate wiring configuration is required if the 0/4-20mA transmitter output is to be first (also)
sent to another data acquisition or control device.
Example of pH Control Application using TPC Mode
The required settings needed for this TPC implementation are:
Limit: Hi (Max limit) or Lo (Min limit); Here a max limit is needed.
Control mode:
TPC
Setpoint: Requested pH value; here 9.8pH
Proportional band: Band where the actual regulation is performed; here 1pH
Unit Basic time:
“Cycle time” for the TPC algorithm
Start timer: Startup time for the sensor to settle
When the measured value crosses 5% of the measuring range (here corresponding to 0.7pH) the
startup timer is activated to avoid false readings during settling time of the sensor. This time should
be selected large enough to give the sensor time to settle, but not much longer than this, since the
supervision and control will be disabled in this period. The relay is off in this condition (see period 1
on figure).
After expiration of the startup timer the FX-300-REL starts to control. In the example, the measured
value lies below the setpoint minus the proportional band (Period 2) and the relay will be continuously
on to use maximum conditioning fluid. When the measured value exceeds the setpoint minus the
proportional band the values is said to lie
8 Additional Measurement & Function Modules
FX-300-REL Relay & Control