Data acquisition system cuts test time

Milwaukee, WI--Switching to a new portable data acquisition system helped P&H Mining Equipment decrease by more than 50% the time needed to perform its typical mining machine tests. The Model 2500 Field Computer System (FCS) from SoMat Corp. (Champaign, IL) has also cut postprocessing time from as much as 500 hours down to 40 hours. P & H uses the FCS primarily to collect fatigue data, which helps determine life estimates of welded structures. Engineers use the estimates to establish preventative maintenance schedules for equipment to avoid costly field repairs.

Previously, P & H performed tests with a "micro-measurements" completion bridge and an analog data acquisition system. Although the system collected all the data needed, James Fleuchaus, project engineer at P & H, notes it had several drawbacks. Among them:

- The system was bulky, making it difficult to transport to the mining test sites. And it was unreliable in the vibration and dust of the test environment, requiring a back-up system.

- Data collected was in ASCII format, resulting in very large files that were time consuming to download.

- Postprocessing had to be done on a workstation and involved converting raw data into meaningful values and then plotting results. The process took between 300 and 500 hours and limited the amount of data immediately available to design engineers.

Enclosed in an aluminum case, the SoMat 2500 FCS can withstand the mining environment, so engineers no longer need a backup system. And since the bridge completion circuits are built in, transporting test equipment to a mine is now much easier. Plus, the system's ability to perform data conversions on the fly has eliminated the need for a workstation, decreasing post-processing time.

A typical test involves up to 150 strain gauges placed at various locations on a machine. Readings are taken from 16 gauges corresponding to each of the 16 analog channels on the FCS. Once data from a set of 16 gauges is acquired, the process is repeated until data has been gathered from all the gauges.

Set-up files created with SoMat's Test Control Environment software (TCE) control the tests. "Set-up takes as long as with our previous system, but hundreds of hours are saved in post-processing because the FCS can perform--internally while the test is in progress--calculations that were previously done after a test on a workstation," explains Fleuchaus.

The FCS also saves time when downloading data because it maintains data in a binary format, so files are smaller. And, the FCS transmits data through a SCSI port rather than the IEEE port the previous data acquisition system used. "It now takes less than 10 minutes to download data, compared to the hour and a half needed previously," says Fleuchaus.