A few years back I picked up an LM-5520 power / demand analyzer from Enetics Corporation. I got the box to do some harmonics studies for a client that did not really work out, but I have since come to rely on this device as my power quality workhorse. It does one cycle RMS voltage and current logging, THD and individual harmonics, power factor, waveform capture, Delta and Wye power, ground current. Pretty much everything except for high frequency capture. It came with 200 Amp current probes, but I invested in some much more user friendly flexible probes (100/1000 Amps selectable)
What impresses the heck out of me is this company’s foresight in designing a product that is easily upgradeable. I have done software and firmware upgrades to implement Delta power, voltage flicker, and most importantly, waveform capture. (at no additional cost, I might add). Every time I pull this meter out for a site visit, I check the website, and there is often an update to the firmware, the software, or the Excel macros, and the updates take just a few minutes.
With the ability to set up capture based on voltage, current, rate of change, and thresholds, this is an excellent monitor – easily comparable to the RPM power analyzer (without high speed capture) and a fraction of the price (20%. Not 20% less, 20% of the price of the RPM.) It’s not perfect – the GUI is awkward and you need to dump the data into Excel to look at it. But at this price….I am not complaining!