### measure high voltage power consumption (380V - 3 phase & up to 400A)

Hi everybody,
I was researching about measuring high voltage power consumption, then I saw this website.
I read and analyzed some.  The project is very interesting.

May be you can inspire me about how can I measure the power consumption and how can I use the products.

What I need is, to measure the power consumption of some machines.  Each machine is working with 380 V 3-phase  electricity (380V is high voltage and it is used in factories)   and each machine consumes more than 100 A. (up to 400A)

I see the YHDC SCT-013-00  sensor.  It looks great. The problem is machine's using more than 100A and maximum current of this sensor's 100A.

When I check the YHDC websites, there are more powerfull sensors.  But I'm not sure how to implement them to this project.

What do you suggest for me?
If you can offer me a solution, I will be very pleased and grateful.

Thanks,

Burak

### Re: measure high voltage power consumption (380V - 3 phase & up to 400A)

If your load is accurately balanced across three phases, and the phase voltages too are equal, then your problem is greatly simplified. As you have machines and not a whole factory, the first is probably a safe assumption, and given a sufficiently solid supply, hopefully the second will be too.

You only need to measure one voltage and one current to obtain the power. The EmonTx (and the emonPi and emonTx Shield) all accept an input current from a CT, so any CT that is capable of giving you 1.1 V rms across a burden resistor that you choose will be fine (so you need to watch the VA rating - many CTs only give you 0.333 V and that is not enough). If you look on the North America page, there's a good selection of suitable CTs listed there. If you have the neutral available, then you can measure the voltage from line to neutral using the standard ac adapter. That is the easy solution, because then with a changed burden resistor and small changes to the calibration, you can use the standard software.

If you don't have a neutral and you need real power (as opposed to apparent power - VA), then it gets a lot more complicated because of the phase relationship between current and voltage, and you'll need to source a 380/9 V isolating transformer for the voltage reference and you'll need to get and load a special sketch that shifts the voltage wave by 60° in software to do the job.

If this looks hopeful, come back here with more details and we can go through the numbers for you.

### Re: measure high voltage power consumption (380V - 3 phase & up to 400A)

hi Robert,

There is no neutral wire.

But, we are not sure that load is accurately balanced  across three phases.  How can we be sure?

I'm thinking to buy a ampmeter and measure each wire to detect...  or do you have better solution?

On the other hand, there are 40 machines which needs to measure power consumption.

So, we need at least 10 emonTx.  (If 1 CT needs for 1 machine)

Is it possible to connect 10 emonTx to 1 emonBase?

​In your responce, you write " North America page"  .  Which page do you mind?  Can you send me directly the product page? (CT that is capable of giving you 1.1 V rms across a burden resistor)

### Re: measure high voltage power consumption (380V - 3 phase & up to 400A)

A search will find the page.

If you have 10 emonTx's transmitting to one base, you will probably find that some readings will be missed because two will be transmitting at the same time and the messages will corrupt each other.

If you do not have accurate details from the machine manufacturer, then you will need to measure the current on each phase. You might find that the difference is not significant - for example, it might only be the control circuit that is causing the imbalance.