ABB COMMANDER 1900 Series User Manual

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ABB COMMANDER 1900 Series User Manual Manual pdf 23 page image

215 ADVANCED CONFIGURATION LEVEL…• Maths5.1.4 Maximum and Minimum Value – Fig. 5.1If the High Value function is selected the maths result holds the maximum value measured on an input variable. If the Low Valuefunction is selected the maths result holds the minimum value measured on an input variable. The maths result can be reset to itscurrent value by an internal or external digital signal.Fig. 5.1 shows the process variable from a flow meter which is continually varying with time. The maximum and minimum valuesare the highest and the lowest samples taken since an external reset last occurred. The external reset can be independent of theaverage reset signal.5.1.5 Real Time AverageThe real time average function averages a continually varying input over a set time scale, between 1 and 1440 minutes(24 hours). Any process variable, remote set point or other maths block result can be averaged. The maths result can be reset toits current value by an internal or external signal.Fig. 5.1 shows the process variable from a flow meter which is continually varying with time. At 0 minutes an external digital inputsignal resets the average to the current value measured. The process variable is then sampled for 10 minutes. The averagefunction result is the average value of the process variable over the 10 minutes sampled.Fig. 5.1 Example of Average, Maximum and Minimum FunctionsAverage Time (10 Minutes)Minimum ValuePV(Flow Rate)Time (Minutes)0 10Maximum ValueExternal Reset SignalAverage