Feature request: Get CT amp values

[haggis663]

Currently we get the CT watt values, but in order to monitor other phase circuits (in a single phase supply to Zappi) (e.g. a second phase), we need the amperage back for the CT (to exclude phase angle calculations)

[G6EJD]

In AC electrical engineering terms; current is a near useless measurement without its power factor (phase relationship)

Only real power is relevant, 1000W examples:
A simple current reading = 1000/230=4.35A
but:
PF = 0.1 real Power = 100W and current = 1000/230=4.3A but real current = 100/230=0.43A

PF = 0.9 real power = 900/230=3.9A

So you'll get two readings 0.43A or 3.9A

You can easily get current from power / voltage, both of which are available, so make a sensor that creates an entity of power/voltage.

But ideally power = voltage . Current . PF

So for the sensor:
current = power / (voltage . PF)

This isn't an issue, it's a request, but you can implement the requirement yourself!

[AJediIAm]

I don't see how relevance is relevant here. If the information is available, it can (and maybe should) be provided to the user.

[G6EJD]

Maybe but it will be close to useless information unless combined with a PF.

Whilst ME used-to supply phase current it was not corrected for PF just the amplitude. Their timing system works out the Power, which is sent anyway along with the current voltage value, which is as I said available, therefore a simple sensor that divides power/voltage will give the current - it's simple electrical engineering.

An implementation will likely create ongoing queries of 'readings don't match' and 'I'm getting the wrong results' because in its raw form it will be of no value other than an interesting apparent random number!

To reiterate; when PF is low Apparent current can be huge and vice-versa, or when PF goes negative all the polarities will be wrong,then there will be a further complication of Real current screening the results.

As designed and implemented the integration is perfect, but needs to be understood to know why.

[haggis663]

I get the power factors for each phase from a smart meter, so hence the w=Amp x phase voltage x phase power factor i.e. this is relevant. The alternative I have to do now is work out the delta phase angle, convert the reading using the relevant phase voltage to amps and then work out the watts as mentioned above. Given timing difference between the smart meter and Zappi, this reverse calculating amps is not as accurate as a direct read.

[G6EJD]

Yes but a Smart Meter only reports every 30-mins and PF varies every reading in other words every second.

As the data is already provided; albeit in a different form of Power and Voltage it would be so much easier to simply create a pseudo sensor with your chosen entity name say Phase2_Current and then with the states function get it to return Current.

You do know that another phase will be out by 120° and the MyEnergi system will not return anywhere near the correct values because of this! So to be honest it's a futile exercise.

Further more I doubt it will even work, as there is no system phase voltage to work anything out.

If you use a Harvi set to 3-phase mode, then it will simulate the phase voltages but then this getting very complicated for what sounds like a very simple task, it isn't.

[haggis663]

I am using a 3 phase Fronius smart meter that update every 30s, not minutes. To reverse calculate the net phase angle, the grid real power per phase gives direction for each phase which indicates the basic difference of 60 vs 120 degrees along with the power factor given a arccos angle for the phase i.e. the 60/120 + target phase angle- original phase angle allows for the calculation of the net phase angle difference. this can be used to reverse calculate the measured watts to find the amps. This calculation suffers from timing differences. (Calculation is done in a template sensor)

The easiest is just to get the CT amps and multiply by phase voltage and phase power factor (use a template sensor to do this).

[G6EJD]

OK, so why not use a template sensor that takes the supplied phase voltage and Power to calculate Amps by dividing the phase power (already PF corrected) by the phase voltage. It's that simple, with no cross system measurements required.

It would take about 1-min to implement as you already have all the data once another CT is fitted, or maybe already fitted.

It must be a ME CT.

[haggis663]

OK, so why not use a template sensor that takes the supplied phase voltage and Power to calculate Amps by dividing the phase power (already PF corrected) by the phase voltage. It's that simple, with no cross system measurements required.

It would take about 1-min to implement as you already have all the data once another CT is fitted, or maybe already fitted.

It must be a ME CT.

I am now a bit confused.
Note that I am monitoring via CT a single component on the load phase, not the entire load of the phase that the Fronius smart meter is reading.

The myenergi integration only supplies me with the monitored CT watts i.e. The Zappi is on a single phase and CT4 is measuring the another phase's load. The Zappi console correctly shows the load's amps and net phase angle. The watts it produces for the load is incorrect as it referenced to the Zappi phase, not the load phase.

To sort this out, the load CT's amps would be ideal and a template sensor is trivial.

[G6EJD]

The ME system you have sounds like a single phase unit. In which case you will not get a phase voltage for let's call it phase2. This is why I mentioned having to use a Harvi set to 3-phase, then the ME system will simulate 3-phases by taking the measured phase1 voltage and delaying it by 120° then publishing it as phase2 voltage from which the correct values can be calculated.

If you have a single phase Zappi, then you will have as data:

1. Phase1 voltage
2. Phase1 power
3. Phase1 PF
   If you then fit another CT on Phase2 then it will display the phase2 current, but it won't make sense as you've found as it does not have a phase2 voltage.

If you have a 3-phase Zappi, then you will have as data:

1. Phase1, 2 and 3 voltages
2. Phase1, 2 and 3 powers
3. Phase1, 2, 3 PFs
   If you then fit another Phase2 load CT presumably to an Eddi; as you'd be out of CT slots, then it will show you the power on the Phase for the CT4 load values, from which current can be determined.
   As I said, you can add a Harvi set to 3-phase which will give you 3 extra CT slots.

I am puzzled as to why you want to display Current as in electrical engineering terms it's useless, as it can't occur unless there is an accompanying consumption of Power and it is Power (real or imaginary) that is doing the work! So all you need to do is monitor power and we are back full circle.