Synchro-Waveforms

What Is a Synchro-Waveform?

A synchro-waveform is a power system’s voltage or current waveform itself, recorded as raw samples stamped with absolute time from GPS or the Precision Time Protocol (PTP). Waveforms recorded anywhere in a facility or across a grid line up exactly, so a disturbance can be traced from where it starts to everywhere it reaches. The device that records them is a Waveform Measurement Unit (WMU).

The IEEE Power & Energy Society set out the field in a 2024 technical report (PES-TR127), and NASPI, the North American SynchroPhasor Initiative, now gives it dedicated sessions. Some literature calls the same data time-synchronized point-on-wave (POW) measurements.

Why Phasors Matter, and Why They Are No Longer Enough

Phasor measurement units (PMUs), developed at Virginia Tech in the late 1980s by Arun Phadke and James Thorp, brought time synchronization to the grid (Phadke and Bi, 2018). A PMU reduces the waveform to the magnitude and phase of its fundamental and reports that phasor 30 to 60 times a second. Time-aligned phasors let operators watch angle separation, power swings and stability margins across an interconnection, and deployment grew after the 2003 Northeast blackout. PMUs remain the backbone of wide-area situational awareness.

A phasor assumes a steady sinusoid at the fundamental, which the grid of that era largely was. Today’s grid runs on power electronics: inverters, drives, chargers and data-center loads that switch within a cycle, inject harmonics and supraharmonics, and oscillate faster than a phasor stream reports. A phasor filters that behavior out.

From Phasors to Waveforms

A WMU keeps the PMU’s time reference and drops the reduction to a phasor. It reports the samples themselves, with every harmonic, interharmonic, transient and sub-cycle event a phasor discards.

WMUs have spread far more slowly than PMUs, for two reasons. The first was need: while slow electromechanical dynamics were the grid’s main stability question, phasors answered it, and full waveforms looked like overkill. The second was data. Phasor streams once strained utility communications too, and a WMU at tens of kilohertz produces orders of magnitude more, so utilities kept waveforms only in recorders that save a few seconds around a trigger. Both have changed: power electronics create the need, and edge processing, inexpensive storage and fast networks remove the barrier.

Continuous or Triggered

The term “synchro-waveform” says the samples are synchronized, not that the record is complete. Per the IEEE report, a WMU may stream continuously or report only when it detects an event, so a time-synchronized fault recorder or power quality meter qualifies too. Recording continuously compounds the data challenge above: a triggered WMU carries its full rate for a few seconds around each event, a continuous one around the clock. In return, nothing is missed, and that decides what an investigation can find. The gapless record is called Continuous Point-on-Wave (CPOW), and its primer covers the even harder problem: finding what matters in a record that size.

One Device, Both Measurements

PMUs and WMUs are not competing instruments. Phasors can be computed from synchro-waveforms at any reporting rate, but a waveform cannot be rebuilt from its phasors. A device that samples fast enough, keeps accurate time and can compute phasors while it records every sample is both at once.

How Energy Quotient Records Synchro-Waveforms

EQ Wave™ is a WMU that records continuous synchro-waveforms: three voltage and four current channels, sampled simultaneously at a fixed 32 ksps and 24-bit resolution, with no triggering, resampling or summarization. The platform computes phasors, RMS values, harmonics and spectra at the edge from that same record, so one installation provides both views, and EQ Syntropy™ applies physics-grounded AI across devices to find and explain the events that matter.