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• Meross EM16P - Accuracy LOG#1

  Jesse Farrell • 26 minutes ago • 0 comments

  Background

  I’m continuing my Home Assistant journey with cheap and cheerful branch energy meter. Like other devices I’ve tinkered with, the Meross EM16P can be controlled locally, though it does offer some cloud features.

  The EM16P includes 18 CT inputs along with 4 voltage inputs, the majority of those CT’s are rated for 60A, with 2 rated for 200A. As someone who’s deeply involved in energy metering at work, I can’t resist diving a bit deeper when I get my hands on a new shiny bit of gear, even if it’s consumer grade…

  Meross’s website makes one accuracy claim we can use as our baseline for this accuracy test. “Professional-Grade Accuracy: Delivers high measurement accuracy with an error margin within ±2%.”

  Test Plan

  To verify this ±2% claim, I’ll be looking at instantaneous readings of voltage, current and real power, while varying one of voltage, current, power factor, or frequency.

  These so called “accuracy sweeps” will include the following test points…

  Sweep Type	Current [Arms]	Voltage [Vln]	Power Factor	Frequency [Hz]
  Test#1 - Current	0.01 - 20	120	0.999	60
  Test#2 - Voltage	1.0	100 - 240	0.999	60
  Test#3 - Power Factor	1.0	120	-0.999 - 0.999	60
  Test#4 - Frequency	1.0	120	0.999	50 - 60

  My reference is only rated for 20A, and most of the circuits the EM16P will measure are 15/20A anyhow. The voltage sweep is limited by the power supply of the EM16P, and same goes for the frequency sweep.

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