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EE Evolution:

Years of Test Technology Powering Test by Tom Lecklider, Senior Technical Editor

EE-Evaluation Engineering continues to celebrate its 50th year of publication by focusing on power supplies and power supply test. The vintage photo of a Siemens-Schuckertwerke Type WJD 700/300 Electrical Machine is appropriate for a power story although we weren’t at the Nürnberger Werk in 1908 to cover completion of the company’s 200,000th machine. Nor did we feature power supplies until the 1980s. That’s not to say that there was no mention of power supplies, just that of- ten they were part of a larger topic, such as power conditioning for ATE.

By the late 1980s, the editorial calendar listed various types of instruments and re- fl ected importance or popularity by the num- ber of articles written each year. An ATE power conditioning article ran in the Janu- ary/February 1983 is- sue and again in 1984, 1985, and 1986. A power supply round-up article ap- peared in April 1987. In the December 1987 issue, Sola advertised UPS and regulator capabilities and BMI power monitoring. An Elgar ATE power ad ran in November 1988, and one from IntePro in December addressed power supply testing.

The December 1989 issue featured a Teal Electronics article on power conditioning and monitoring. Seven power-related articles were published in 1990, perhaps the largest number in the ’90s, but throughout that decade, typically four to six power stories ran each year.

Switch-mode supplies were featured in a 1992 article, “Higher Switching Frequencies Pose Testing Challenges.” And, more highly integrated components were changing power supply design as discussed in a 1990 article. The term smart power seems to have been short-lived although the technology certainly was not. Especially for switch-mode supplies, power ICs with integrated monitoring and control circuitry are the starting points for modern designs.

36 • EE • February 2012 Programmable power supply operation has an obvious link

with ATE, but transient performance can adversely affect DUT testing in several ways. Load transient response attracted at- tention when power supplies were used to simulate batteries in cell phone testing. A number of articles addressed this topic from 1998 to 2002.

Completing the 200,000th Machine Courtesy of Siemens Corporate Archives, Munich

Many distinct product segments emerged including program- mable power, fast tran- sient response supplies, high-voltage supplies, high power density mod- ules, solar panels and related inverters, and power-over-Ethernet ap- plications. In addition, related equipment such as electronic loads and four-quadrant source- measure units (SMUs) had matured into sepa- rate product lines. The September 2009 article “In Search of the Zero-Ohm Load” dis- cussed electronic loads in detail, using examples from Amrel (now part of AMETEK), Chroma Systems Solutions, Ki-

kusui, and PPM (now sold by Kepco). Solar power simulators were covered in the May 2010 “Lights-Out Solar Power” article. Keithley Instruments’ SMUs now compete with instruments from National Instruments and Agilent Technologies. The very large SMUs, such as AeroVironment’s 800-kW AV-800 used for electric vehicle development, were featured in the June 2011 Special Report “More Than Just a DC Load.” AC power sources also have been the topic of in-depth editorial coverage. An Elgar article ran in 1999, “Specifying an AC Power Source,” and AC sources have been included in several power supply and sources round-up articles during the last decade. “Selecting a Linear or PWM Power Source” by Pacifi c Power Source published in November 2008, and AC power sources again were discussed in the August 2011 Special Report “Flexible and Uncorrupted Power.” As we enter our 51st year, we will feature topics such as the smart grid and solar power generation in addition to our coverage of DC power supplies and AC sources.

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