July 2004 

Below are listed featured articles from the July 2004 issue, Vol. 57, no. 7 © 2004 Barks Publications, Inc. ... see also July 2004 departments and columns and Previous issues.

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• Shop equipment showcase    Another installment of our popular periodic roundup of the latest tools, equipment and devices that can increase service shop productivity and safety, while also enhancing the value of the repair jobs and services provided for customers.  By the EA Staff

• The fine art of load testing d-c motors    D-C motors have survived all predictions that they are destined to disappear, so service specialists need to stay on top of the best techniques to anticipate operating problems and keep d-c equipment running at peak efficiency. This important article reviews the three basic methods for load testing d-c equipment to check temperature rise (particularly in the armature), establish torque capability, and determine efficiency ratings.
  Read an online summary (trilingual summary appears in the magazine) By Richard L. Nailen, RE., EA Engineering Editor

• Why install an isolation transformer?    For users of adjustable-speed (variable frequency) motor drives, “inverter duty” implies that one of two major problems may arise. We’ll first walk readers through how to watch for, and take steps to prevent, the damaging effect of output voltage spikes on the motor circuit itself, which has led to the development of “inventer duty” insulation systems and special interconnecting cable. We’ll then discuss how to take measures to guard against the flow of harmonic currents in the power supply system, which can generate damaging harmonic voltages throughout the system. By Richard L. Nailen, RE., EA Engineering Editor

• Summertime, ice cream, and data acquisition    How an ice cream-making machine can lead to an understanding of how data is gathered, organized and used  By David P. Tryling,  EA Electronics Editor

• Protecting employees against low-voltage shock  Beware the hazards of not showing low voltage the same respect as high voltage  By Richard B. Elsberry, EA Contributing Editor

• Judging management by its numbers   How to base evaluations on figures that don't lie.  By William H. Wiersema, CPA, EA Contributing Editor

See also July 2004's Departments, columns