Power Quality Issues Detection Time Windows

Just wanted to document the time horizons that the Sense Labs Power Quality detectors use to flag / log issues, since both answers were raised recently. There are two:

  • Sustained - Highest and lowest 7 second moving average on each leg over the past 30 days. These values, along with the current leg voltages are shown next to, or just below the voltage waveforms.
  • Instantaneous - All 1 second moving average voltage events above or below +/- 10% of the 120V nominal. Based on what I have measured, and @JuliaAtSense notes, Sense uses an absolute 108V floor and a 132V ceiling, rather than basing it on your nominal average. The most recent instantaneous issues are listed below the Power Quality graph along with a summary of all events over the past 30 days. You can download all logged events via the CSV download icon. Based on data coming out of Sense, the Power Quality detector can spot several 1 second violations on the same leg within a single second.

Just to confirm, you’re saying integration period for “instantaneous” measurements is one (1) second, so if we have a voltage condition +/- 10% of 120V nominal for one second or greater, it will be logged as a dip or spike and appear in the list of “Dips and Spikes” in the Labs Power Quality UI?

What should we expect in terms of delay for these measurements to be available in the cloud UI? I ask because we are experiencing storm-related transient dips right now, quite possibly <1s, but nothing is visible in Sense.

Hi @jeff5,

Here’s what I know, and don’t.

  • Sense uses an absolute 108V floor and a 132V ceiling for dips and spikes, rather than basing it on the % of your nominal average.
  • The update period for the power quality graph runs from a day to a few days. So you won’t catch anything realtime.
  • I don’t know how often the voltage data is sampled and stored for Power Quality - obviously at least once per second. One users has speculated that Sense does microsecond sampling / calculation for power, but doesn’t collect voltage anywhere near as frequently.