MTS Multipurpose Elite - Manual (Page 642)

• Full-Scale Percentage
• Statistical Limits from Table
• Range Percentage from Table
Definitions for Limit Calculations
Range = Max - Min
Midpoint = (Max - Min) / 2
Statistical Percentage method
LowerLimit = Statistic * (1 - LowerPercentage)
UpperLimit = Statistic * (1 + UpperPercentage)
Full-Scale Percentage method
LowerLimit = Statistic – LowerPercentage * Range
UpperLimit = Statistic + UpperPercentage * Range
Calculate Trend Limits
Both the Statistical Percentage and Full-Scale Percentage methods use the same Lower Limit and Upper
Limit values for all calculations.
The Statistical Limits from Table method uses the limit value for each statistic for each signal selected in
the Limits Settings Table window.
The Range Percentage from Table method uses the same table, but the limits are expressed as a
percentage:
Note:
For the Range Percentage from Table method, the lower limit percentage is a negative value, and
is added to the midpoint as follows: LowerLimit = Midpoint + LowerPercentage * Range / 2 UpperLimit
= Midpoint + UpperPercentage * Range / 2
Signal Range in Trend Calculations
The Full-Scale Percentage and Range Percentage from Table methods both specify a percentage to
calculate the limits using the full-scale range.
The Range Percentage from Table method uses half the full-scale range (Range / 2) because it is
calculated from the midpoint value (in this case, entering 100% yields an upper limit equal to the full-scale
maximum).
The Full-Scale Percentage method is calculated from the statistic value, which may be near the full-scale
minimum, making the difference twice as large (this method uses the full-scale range, not the Range/2).
642 | MTS TestSuite
Appendix: Trend Monitoring