Why does my digital multimeter not always agree with the voltage shown on the control’s display?


 

Why does my digital multimeter not always agree with the voltage shown on the control’s display?

  • Not surprising as the utility voltage is constantly reacting to load changes, transients, harmonics, and induced noise on its powerlines.
  • To provide the most accurate view of the line voltage, Beckwith Controls introduce a minimum of filtering and averaging. This is why the voltage display can appear “jumpy.”
  • Typical handheld digital voltmeters introduce a greater amount of averaging and occasionally filtering. This makes the voltage appear more stable than reality.
  • Many multimeters have a relatively narrow operating temperature range. Operating beyond those limits creates a temperature coefficient that changes the rated accuracy.