Sense is not picking up voltage or watts but is connected

I lost the internet for several days and when the connection was re-established my monitor is showing zero watts and voltage. I’ve tried turning off power and restarting. I have tried troubleshooting the monitor.

some feedback:
Under network connections → wifi i find it suspicious that it says “Enabled Disabled”
Just like your networking is disabled.
Since you are showing this on the desktop web page of means that networking IS enabled.

It should give voltage reading at least, since the unit is powered from the same leads where it measures the voltage.
Since it doesn’t seems to measure anything but it does mention 63 Hz (which is way too high frequency for the grid) i must come to the conclusion that either something is not initialized correctly but since you mentioned you power cycled already, that should do the trick.
That leaves me to the conclusion that you have defective hardware.
Why where you without power for several days ?
Could there have been spike in voltage that fried the electronics ?
Is there other equipment in your home that no longer works ?

@mike8, @dannyterhaar pointed out one additional clue - if your frequency really is 63.1, you might be outside the range where Sense will actually operate correctly. Or your grid frequency might be so variable it is giving Sense trouble. Who is your utility ?

I am pretty sure the sense unit will work up higher frequencies.
The PSU is a switched powersupply who first rectifies to DC and then lowers it with DC-DC conversion.
Most equipment with a switched power supply wouldn’t mind 80 hz if needed, and that is why input is mostly general for around the world 50-60 Hz.

Measuring voltage is also pretty independent from the freq.
I am pretty sure the sense unit under UL1741SA (freq shifting solar for AC coupling) which goes up to 62 Hz is not an issue.
63 isn’t that much higher.

Agree with you on the PSU - not an issue. But if Sense is really taking 1/2 million voltage samples a second, there’s a huge difference between 60Hz and 63Hz - 400 samples difference each cycle. Here’s just a simple simulation at 500,000 samples / sec. 60Hz (black) and 63Hz (red) waveforms side-by-side for 1/10 second. Note the 170V peak.

Here are the results of the RMS calculation over a moving 60Hz cycle at 500,000 samples per second with a 3333 sample window (1 cycle). 60Hz RMS in black, 63Hz RMS in red. The 60Hz RMS voltage measurement is rock solid at 120V. The 63Hz RMS oscillates by 5V over time because the sampling period doesn’t exactly match the frequency.

I’m sure Sense adapts sampling rate to compensate within a frequency range, but if the base frequency fluctuates too widely or rapidly, you really don’t want to count on RMS voltage or power measurements.

I assume the frequency reading is not measured by interpreting the samples but measuring time between crossovers.
The grid in California technically could vary between 58-62 Hz with rule21/UL1741SA.
US sense models seem to work great in 50 Hz territory.

Samples per second don’t seem to change.
So computing power is the same. Weather 50/60 or 63 Hz.
Still 500k samples per second

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should say ‘March 9th’

thank you Kevin and Danny for the input… I hope that power surges have not damaged the Sense monitor electronics… The reason I purchased the system is to monitor and record the power usage… a feature that is not functioning now.

Voltage dips and spikes seen to have been high on March 9th. I have forwarded a request to the Sense support for their insight into the problem.


All the equipment seems to be working fine… except the Sense monitor. I am in the California foothills… we have had huge storms recently, accompanied with power and internet outages.

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PG&E is the utility. We have experienced power outages and some significant power drops in the past few days.

I didn’t want to try ‘restarting’ the monitor and loose all data, but I did finally execute a ‘restart’ and now the thing works! Thank you! I appreciate your help.

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That’s great. When you say “I finally executed as restart”, what did you mean ?

  • Data Reset
  • Factory Reset
  • Something else ?

ps: I’m on the PG&E grid as well, but in the flatlands of the SF Peninsula. Saw a major outage a week and a half ago, but only a small number of voltage excursions.

If you PM me or post your CSV of out-of-range events, I’ll plot for you like this. (Unless of course, you reset away that data).

@dannyterhaar , you’re right - Sense will use something like zero-crossing to calculate frequency, and adjust. But my main point is that even a smallish instability in frequency makes RMS calculations inaccurate, because frequency, sampling and RMS calculation techniques are all interrelated.

Why are you focussing on RMS & frequency.
Like I wrote before:
A split phase USA unit is succesfully being used on a split phase 50 Hz setup.
If the setup/core of Sense was build around a fixed frequency, that setup should not work [TM]
But it does.
So maybe RMS is calculated based on freq measured over the last xx(xx) cycles or other time frame.
There is so much possible.

Apart from the being able to use 60Hz equipment on 50 Hz, (as stated before) California grid can technically vary between 58-62 Hz.
According to you that would give a lot of problems to calculate stuff.
I think Sense calculates stuff depending on freq they measure (not assume like you are implying)

You must have shorter leads to the developers, why don’t you ask them :wink:

What I find interesting is 3/9 6:49 AM L1 0.0V L2 0.0V.
How could the monitor itself record 0.0V?
After all the power outages we’ve had I don’t recall my monitor ever showing a “dip” of 0.0v.

Kevin, yes I reset the data, not the factory settings, so all historic data was lost but the thing is working now… I don’t know why wattage voltage were locked out. thanks for your assistance!

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