General Information
Chapter Six: Operation in Tuning Mode
160
The Deviation Indicator
In Tuning Mode there is a deviation indicator which indicates the deviation of the system
pressure from set point. The deviation from set point is displayed approximately every one-third
second (this is how often the LCD screen is refreshed). The deviation indicator is enabled only if
the 146 unit is operating with the
AUTO
feature turned on (refer to How To Set the Valve to
AUTO
Position, in the Operation in Control Mode chapter).
There are ten deviation indicator segments. The five upper segments represent pressure deviation
over set point and the five lower segments represent pressure deviation under set point. The 146
unit determines the segment(s) to illuminate according to the following formula:
Deviation =
P
sp
Where:
P = pressure
sp = set point
Each segment represents a different percent of deviation as shown in Figure 44.
Deviation
Percent Error
Segments
1.2 to < 1.95
1.05 to < 1.2
1.01 to <1.05
1.002 to < 1.01
None = 0.998 to <1.002
0.99 to < 0.998
0.95 to < 0.99
0.80 to <0.95
0.05 to < 0.80
<0.05
> +95%
+20 to 95%
+5 to 20%
+1 to 5%
+0.2 to 1%
0.2%
-0.2 to 1%
-1 to -5%
-5 to -20%
-20 to -95%
> -95%
±
1.95
≥
Figure 44: Deviation Indicator
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