Curve set configuration

A curve set definition is basically a collection of (x,y) coordinates.

Note: If compressor curve definitions from the manufacturer are not provided in tabular format, the (x,y) coordinates may be hard to determine.

The manufacturer may provide either of the following:

• A plot of head pressure vs. flow for the rated speed of the unit.

• A plot of head pressure vs. flow for a number of speeds.

In the first case, you can use the Fan Law to determine additional (x,y) coordinates. In the second case, you can obtain additional (x,y) coordinates directly from the plotted curves.

Because of the amount of data required to define all of the curves in a RealTime database (RTDB) curve set, a Microsoft Excel spreadsheet template is normally used for data entry. Required data includes the name of the curve, surge alarm limits, curve data, and curve labels.

The completed spreadsheet is converted to an ASCII file, which is then loaded into the RTDB curveset table using the load_curvesets tool. The load_curvesets tool is a C# script that enables bulk loading of performance curve data.

Note: Only the name of the curve set associated with a compressor is maintained historically in the Historical Service. Curve set definitions are stored in the RTDB. Therefore, only the curve set that is currently defined in the RTDB can be displayed in easy eXtended Operator Station (ezXOS).

Summary of Steps

1. Create a Curve Set Data File (refer to Create a curve set data file).

2. Load a New Curve Set (refer to Load a new curve set).

3. Configure the Curveset Table (refer to Configure a curve set record).