Selection of Equipment for Power Measurement or Surveys

When choosing equipment to conduct a power survey, many presentation formats are available including indicating instruments, strip chart recorders and digital devices with numeric printout. For most survey applications, changing loads makes it mandatory for data to be compiled over a period of time. This period may be an hour, day, week or month. Since it is not practical to write down varying readings from an indicating device for a long period of time, a chart recorder or digital device with numeric printout is preferred. If loads vary frequently, an analog trend recording will be easier to analyze than trying to interpret several numeric reports. Digital power survey monitors are typically less expensive than analog recordings systems. Complete microprocessor based power survey systems capable of measuring watts, VARs, kVA, power factor, watt hours, VAR hours and demand including current transformers are available for under $3000. With prices for memory and computers going down, digital devices interfaced to disk or cassette storage will provide a cost effective method for system analysis.7

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