WATLOW Series 988 User’s Manual 8.15
General Software Features, Chapter 8
General Software
Sample Application
A waste water process engineer needs to control the flow of a solution to
be mixed with wastewater to treat it. The transmitter provides a 4-20mA
output without square root extraction. The engineer used the Series 988
with a universal signal conditioner input and a 4-20mA process output to
control the flow. The input signal was linearized using the square root
extraction feature of the 988.
The above system has a flow range of 0 to 16 gallons per minute. The
range low and range high parameters for input 1 would be set to 0 and 16
respectively. The input 1 linearization prompt [lin1] would then be set to
square root extraction [root]. You can see from the above graph that
without square root extraction to linearize the signal it would not be use-
ful for controlling the process.
