[Equest-users] Performance Curves - independent variable boundaries

[Phil Jordan]

When a curve output exceeds the limits (min/max output, OUTPUT-MIN and OUTPUT-MAX keywords), eQUEST throws a CAUTION message in the SIM file, something like this:

**CAUTION**********************************************************************

             In curve: Variable Speed Drive FPLR        the dependent value

             is exceeding the limits.

             Value/Min/Max/First time:          1.004          0.100          1.000   7/21/ 8




I'm curious, what happens when the input type for a performance curve is "Raw Data Points" and during the course of the simulation one of the independent variables is outside the range of the raw data points? For example, here's a curve from the library (BDLLIB.DAT) that's defined via data points:
$LIBRARY-ENTRY SmFricW3VSD-EIR-fPLR&dT         CURVE-FIT       Sml Fric 3App    -044d2  35
$ 70/140 ton, 3F approach evap & cond; R134a extended 460V  10F superheat       -044d2  36
$ EIR = 0.182, 0.64 kW/ton, COP 5.5                                             -044d2  37
   TYPE = BI-QUADRATIC-RATIO&DT   INPUT-TYPE = DATA                             -044d2  38
   IN-RATIO = ( 1.00, 0.75, 0.50, 0.25,  $ PLR                                  -044d2  39
                1.00, 0.75, 0.50, 0.25,                                         -044d2  40
                1.00, 0.75, 0.50, 0.25,                                         -044d2  41
                1.00, 0.75, 0.50, 0.28 )                                        -044d2  42
   IN-DT    = ( 41.0, 41.0, 41.0, 41.0,  $ ECT-CHW DT                           -044d2  43
                31.0, 31.0, 31.0, 31.0,                                         -044d2  44
                26.0, 26.0, 26.0, 26.0,                                         -044d2  45
                46.0, 46.0, 46.0, 46.0  )                                       -044d2  46
   OUTPUT  = (  1.00, 0.70, 0.46, 0.27,  $ EIR ratio                            -044d2  47
                1.00, 0.66, 0.39, 0.22,                                         -044d2  48
                1.00, 0.65, 0.38, 0.19,                                         -044d2  49
                1.00, 0.72, 0.50, 0.32 )  ..                                    -044d2  50

In the data points, the minimum PLR boundary for the curve is 0.25 - what happens if during the simulation the PLR is 0.20? Does eQUEST use the curve output regardless (and is a CAUTION generated), or is the output at the minimum independent variable used?

Thanks,

Phil Jordan

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