Measuring battery plant ripple currents

Utility users of uninterruptible power supply (UPS) have become concerned with the premature wear-out of the battery systems. In looking for a cause for accelerated battery wear-out, a study of the electrical environment was made in order to identify the differences between the relatively new UPS applications and the older telecommunications applications. The types of sites from which data were taken are: central office and PBX telecom, single-unit UPS, multiple-unit UPS with individual battery systems, and multiple-unit UPS with a shared battery system. In most instances the load on the DC system was unknown. Several UPS brands were tested to get a representative sample. The author describes the data acquisition system used and data reduction issues and proposes a standard method for data acquisition and a recommended instrument list.<>