emontx - multiple inputs

Hi all.

I am considering getting a OpenEnergyMonitor system, but I have some questions before purchasing.

My goal: I would like to monitor and log the power consumption of my heatpump, using 3 CT current sensors.(it's a three phase power thingy)

At the same time, I would like to monitor the current power usage as indicated by the blinking LED on my meter (10000 pulses per kWh).

Can a single emontx log these 4 variables simultaneously?

Visually, I would like to have these two "real time indicators" displayed.

Does the emontx just collect data for all its inputs and send them out wirelessly, and then the firmware in for instance an emonlcd is responsible for, in my case, adding the currents for the three CT sensors together, and multiplying with voltage to get power, and display that - while also handling the pulsecount-to-power usage calculation and display thereof?

TIA.

Robert Wall's picture

Re: emontx - multiple inputs

If you have a 3-phase supply, then with only one voltage being monitored you will only have an approximation of the power in the other two phases. If that is good enough, then one emonTx will do what you want. If not, then you can either replicate the voltage input twice more (the analogue inputs are available, but unused), or you can stack 3 emonTx's as here.

Does the emontx just collect data....? No, the power calculation is done in the emonTx, so you will add the three powers and send the result. For the meter pulses, if you don't require logging (when normally the pulse count is sent) then you could quite easily calculate the pulse rate, which will give you another value for imported power.

The emonGLCD is pretty much full handling the display and there's almost no spare capacity for much else.

[Edit] As the 3-phase load is a single unit, it ought to be well balanced across the 3 phases, so it might not be necessary to measure 3 currents after all. You'd need to check that.

calypso_rae's picture

Re: emontx - multiple inputs

At the same time, I would like to monitor the current power usage as indicated by the blinking LED on my meter (10000 pulses per kWh).

That's a blinking lot of pulses - I think you mean 1000/kWh

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