In a load for testing an energy production device, such as a fuel cell, a technique is provided for sensing one or more operational parameters for each of a plurality field effect transistors. Analog and digital feedback are provided to adjust the control signal to the FETs to ensure that each remains within its individual safe operating area. The technique preferably takes all of the various operational parameters into account to determine if any individual FET is approaching the SOA boundary, and prevent that single FET from leaving the SOA while continuing to manage the operation of the entire load.

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