How to handle 400A or even 800A residence

digitalshaman · 2023-03-14T16:06:53.536Z

Any suggestions to handle exceptional homes consuming 10-20xs the electricity of an average US home (3 phase)?

How to modify the system or add other components to handle larger currents and amperage?

This too could apply to multi unit housing and commercial buildings and properties.

The emphasis is on consumption, not production per se.

Thank you in advance.

Robert.Wall · 2023-03-14T16:37:50.411Z

Are you thinking in terms of OEM equipment, or something else?

The first question is, do you really need the capacity to measure the currents you mention, because it’s rare that the actual current drawn gets close to the nominal rating of the supply.

If you are thinking in terms of OEM equipment, then the starting point is the emonTx4’s input accepts the output from a 0.333 V current transformer, so if you get 400 A or 800 A (or even bigger) c.t’s with 0.333 V outputs, then in principle all you need to do is change the calibration to read 400 A or 800 A instead of the default 100 A.

The requirement for the emonPi is instead a c.t. with a secondary current of 50 mA at 400 A or 800 A primary current, and again change the calibration to suit.

What I have not done is checked at what point the internal maths will overflow when the numbers are (maybe) 8 or more times bigger than we’re ever likely to see in the UK.

digitalshaman · 2023-03-14T17:15:20.194Z

See my responses & question please - indented

Are you thinking in terms of OEM equipment, or something else?

/ Whatever we can work with. It’s a large residence (actual several) in Florida. So, not single phase.

The first question is, do you really need the capacity to measure the currents you mention, because it’s rare that the actual current drawn gets close to the nominal rating of the supply.

/ Yes. That is what we are trying to make work given the amount of monthly cost of electricity - $8000. There is going to be some difference between the utility meter (which looks backward, not in near real time) and how the utility set up the connection to the grid (there is loss in the relatively longer connection to the house & it’s fuse boxes)

If you are thinking in terms of OEM equipment, then the starting point is the emonTx4’s input accepts the output from a 0.333 V current transformer, so if you get 400 A or 800 A (or even bigger) c.t’s with 0.333 V outputs, then in principle all you need to do is change the calibration to read 400 A or 800 A instead of the default 100 A.

/ Ok. Do you have a recommendation for equipment? Would be US based. There is a similar need in Bermuda.

The requirement for the emonPi is instead a c.t. with a secondary current of 50 mA at 400 A or 800 A primary current, and again change the calibration to suit.

/Ok. That’s helpful.

What I have not done is checked at what point the internal maths will overflow when the numbers are (maybe) 8 or more times bigger than we’re ever likely to see in the UK.

/ Indeed. That is what we were discussing. Now that more open source hardware is being deployed, what are the limits of the hardware. One related issue in some deployments was operating temperature of the chips. Recently we’ve found a few ways to keep them cooler; but, we had lots of issues with an Enphase meter (non solar related) that was west facing and continually failed - though utility-installed. It was operating temperature problem.

Robert.Wall · 2023-03-14T17:41:49.505Z

It would be helpful if you used the “quote” facility on my questions instead of copy/paste - highlight the part you want to quote and click on “Quote”.

digitalshaman:

So, not single phase.

The emonTx4 + emonVs can work with single phase, North American 3-wire split phase or 4-wire 3-phase systems.

digitalshaman:

Do you have a recommendation for equipment?

I think all the usual suspects can supply appropriate c.t’s. Wattcore, Magnelab and Aim Dynamics are names that spring to mind.

digitalshaman:

what are the limits of the hardware.

The emonTx4 is intended for installation inside a dwelling. It will have a maximum operating temperature of 40 °C.

Mike_Henderson · 2023-03-15T09:22:57.917Z

How about using a CT with a Modbus output instead?

Robert.Wall · 2023-03-15T11:35:48.354Z

Mike_Henderson:

a CT with a Modbus output

Isn’t there something missing from that line?

How do you calculate real power from current coming as a data stream over Modbus?

Mike_Henderson · 2023-03-15T12:38:08.601Z

Robert.Wall:

How do you calculate real power from current coming as a data stream over Modbus?

I’d have to dig into the spec sheet a bit more, but the one I looked at has voltage inputs and provides registers for * Measures Volts, Current, Watts, VAr, VA, Voltage Peak Current Peak, Hz, COS, KWh import, KWh export.

Mike

Robert.Wall · 2023-03-15T12:41:46.239Z

Don’t you need to mention the small detail of a METER being involved?