Voltage Measurement and a small battery backup

[Bmedfly]

It would be nice to have the ability to measure the voltage on two phases. This would increase the accuracy of the power measurement and provide a good view of the fluctuations of the incoming power.

It would also be good if a small battery could be added to the unit to keep taking measurements for a few minutes during a power outage. Shutting down the Wi-Fi would save power and keeping the measurements in a “Wait for Trigger” mode (the power came back) should have a very low power requirement.

[sourceholder]

I don’t believe it’s possible to measure voltage over eddy current clamps. Voltage measurement would require new hardware.

[sourceholder]

It would also be good if a small battery could be added to the unit to keep taking measurements for a few minutes during a power outage.

I noticed Emporia sells an external power supply which you could plug into a UPS. Although not as elegant as an integrated battery solution, it should work.

• This reply was modified 5 years, 1 month ago by sourceholder. Reason: Fixed typo

[Bmedfly]

I should have been a bit more open in my thinking. A transformer could be used to step down the voltage from the 220 mains (on the primary winding), and a precision resistor would be added to the secondary winding. A current clamp would be used to measure the secondary winding. Measuring the current through a known resistor value would give the voltage (V=I*R). Then multiply the measured current by the winding ratio of the transformer. This final product would be the voltage at the main circuit.

Obviously, this would require the above math to be put in the application. The transformer and resistor pack would need to be provided by emporia to keep everything aligned. It could also be used to automatically and dynamically set the circuit multiplier for the other clamps.

[Jim @Emporia]

@Bmedfly and @sourceholder, the Vue that’s currently on the market is not capable of measuring voltage accurately due to hardware limitations. We are developing a new version of the Vue with many improvements, including voltage measurement for each phase. I’ll pass your battery suggestion on to the product team.

• This reply was modified 5 years, 1 month ago by Jim @Emporia.

[Pinback]

Emporia missed an opportunity here. The external power supply could be simply a transformer. All the dc components (rectifier and regulator) could have been put in the monitor itself. Then it would be able to read the ac line voltage from the ac input.

[Author]

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