AC Current Measurement

[Harry D]

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

 

[boB]

On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2k99@gmail.com>
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

Using a current transformer, you look at the current in comparison
with the AC line voltage.

As you start to draw power, let's say a resistive load, the current
will go one direction compared to the voltage.

If you put power back into the grid, the current humps would go the
other direction... Assuming the power factor is 1...

No power, the current will be flat zerol of course.

For PF lower than 1, it can be a bit of both directions but if you
were drasing power from the grid, then the net current would be
negative. More one way or the other.

 

[John Larkin]

On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2k99@gmail.com>
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

 

OK

I don't know exactly what you're after here but I'll wing it.
I assume you know what alternating current is. There is no direction of current flow, so I am assuming maybe you men you want to determine which end is the source.

Current readings will do you no good for that, the current is the same in a series circuit. If you want to know which end is "up" the best way is probably with an extremely extremely extremely accurate voltmeter with more resolution than anyone would ever though they would need. But for this...

If you are at mains frequency forget any and all time domain shit. I am pretty sure none of them even today could tell you accurately at like line frequencies.

That is it. People do not give enough detail. If you did I could figure out quite a bit more. Are you working in a sewer or on a utility pole ? Or is this in a building. At how many points can you get to this particular wire ?

Or is this some project in your LAB-OR-ATORY ? You need bandwidth, wind your own. If you don't need high frequency just wrap ten turns of #12 THHN wire around it and feed a 1KHz square wave through it. Get an audio equalizer and make that coil's waveform a square wave. You'll be fairly accurate through the audio spectrum.

Then for your actual measurement, after the scope is off having done its thing, use a TRMS reading meter.

Maybe you have no interest in what I said here, but I have done well figuring out how to measure, calibrate and align things without using those multithousand dollar machines that are probably good for no other purpose in the world ever.

I can measure your AC current from about 35Hz to about 150KHz. And I don't have to spend a dime to do it.

 

[Phil Allison]

Harry D wrote:

------------------

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?

If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.

** A current transducer (or transformer) will give you an easily read and SAFE voltage analogue of the actual current.

The easiest way to identify which way it is flowing is to use a scope in X-Y mode - with voltage and current waves on each input.

For in-phase waves, the slope of the line on the screen will be opposite in each case.



..... Phil
..... Phil

 

[Whoey Louie]

On Tuesday, August 27, 2019 at 7:04:15 PM UTC-4, John Larkin wrote:

On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2k99@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Nor does it sink or source from a node. Whatever current comes into a
node has to go out, it can't pile up.

Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

And to determine which is the source, which is the load, you just need
to look at the direction the current is flowing and the voltage.
Imagine a battery hooked up to a resistor. If I don't know which is
which, they are hidden, just look at the polarity,which wire is the positive
and then which way current is flowing in that wire. The current will be
flowing from the source to the load. With AC it gets a little more
complicated because the battery keeps changing voltage and reversing
polarity so you have to check the voltage and current at the same point
to figure out which way it's flowing and integrate the power over
time if that's what you're after.

No much more to go on from what's given, as to whether this is a one
time test or he's designing a new widget. Looking at a power metering
IC might be an option, depending on what he's doing.

 

[Harry D]

On Tuesday, August 27, 2019 at 5:32:59 PM UTC-7, Phil Allison wrote:

Harry D wrote:

------------------


Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?

If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.


** A current transducer (or transformer) will give you an easily read and SAFE voltage analogue of the actual current.

The easiest way to identify which way it is flowing is to use a scope in X-Y mode - with voltage and current waves on each input.

For in-phase waves, the slope of the line on the screen will be opposite in each case.



.... Phil
.... Phil

I need this circuit for a Power Meter that will do net-metering in a 20A, 240 Vac 60 Herts power line. It will have a digital readout.
Cheers, Harry

 

[Harry D]

On Tuesday, August 27, 2019 at 11:25:55 PM UTC-7, Whoey Louie wrote:

On Tuesday, August 27, 2019 at 7:04:15 PM UTC-4, John Larkin wrote:
On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2kx@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Nor does it sink or source from a node. Whatever current comes into a
node has to go out, it can't pile up.




Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

And to determine which is the source, which is the load, you just need
to look at the direction the current is flowing and the voltage.
Imagine a battery hooked up to a resistor. If I don't know which is
which, they are hidden, just look at the polarity,which wire is the positive
and then which way current is flowing in that wire. The current will be
flowing from the source to the load. With AC it gets a little more
complicated because the battery keeps charging voltage and reversing
polarity so you have to check the voltage and current at the same point
to figure out which way it's flowing and integrate the power over
time if that's what you're after.

No much more to go on from what's given, as to whether this is a one
time test or he's designing a new widget. Looking at a power metering
IC might be an option, depending on what he's doing.

Let's say we are net metering in a 240Vac, 20 Amps, 60 Hz power line in a digital power meter.
Cheers, Harry

 

[Harry D]

On Tuesday, August 27, 2019 at 4:04:15 PM UTC-7, John Larkin wrote:

On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2kx@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

Grid voltage can be constant so I still have the problem of measuring the voltage difference across a sense resistor in a 250 V CM. That is difficult to do with a 60 Hertz power line. Averaging will help but there has got to be a better way. I have the same problem with the CT.
Cheers, Harry

 

[Jeroen Belleman]

On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D
<td2kx@gmail.com> wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into
(Source) or out of (sinking) a node. (The node is the grid and we
can either supply or sink current to that node). Measuring
current is easy but how do I determine which direction it is
going. Am I sourcing or sinking?

If you need to ask such questions, you shouldn't be doing
this on your own.

Jeroen Belleman

 

[Whoey Louie]

On Thursday, August 29, 2019 at 3:26:40 PM UTC-4, Harry D wrote:

On Tuesday, August 27, 2019 at 5:32:59 PM UTC-7, Phil Allison wrote:
Harry D wrote:

------------------


Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?

If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.


** A current transducer (or transformer) will give you an easily read and SAFE voltage analogue of the actual current.

The easiest way to identify which way it is flowing is to use a scope in X-Y mode - with voltage and current waves on each input.

For in-phase waves, the slope of the line on the screen will be opposite in each case.



.... Phil
.... Phil

I need this circuit for a Power Meter that will do net-metering in a 20A, 240 Vac 60 Herts power line. It will have a digital readout.
Cheers, Harry

Why reinvent the wheel? Buy a digitial power meter. Or if you need to
build, then a power metering chip, and a lot of other components, it's
not trivial. That chip will multiply voltage by current in real-time
to get the power. Without doing that, if say you measured voltage with
one circuit or instrument, current with another, you won't know the power unless
you also know the phase relationship between the current and voltage
and that it doesn't vary. If it's a resistive load, that isn't an issue,
but if it's typical loads for a net metering application, eg non-incandescent
lighting, motors, appliances with power supplies, then the voltage and
current will not be in perfect phase and it changes.

 

[Whoey Louie]

On Thursday, August 29, 2019 at 3:22:07 PM UTC-4, Harry D wrote:

On Tuesday, August 27, 2019 at 11:25:55 PM UTC-7, Whoey Louie wrote:
On Tuesday, August 27, 2019 at 7:04:15 PM UTC-4, John Larkin wrote:
On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2kx@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Nor does it sink or source from a node. Whatever current comes into a
node has to go out, it can't pile up.




Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

And to determine which is the source, which is the load, you just need
to look at the direction the current is flowing and the voltage.
Imagine a battery hooked up to a resistor. If I don't know which is
which, they are hidden, just look at the polarity,which wire is the positive
and then which way current is flowing in that wire. The current will be
flowing from the source to the load. With AC it gets a little more
complicated because the battery keeps charging voltage and reversing
polarity so you have to check the voltage and current at the same point
to figure out which way it's flowing and integrate the power over
time if that's what you're after.

No much more to go on from what's given, as to whether this is a one
time test or he's designing a new widget. Looking at a power metering
IC might be an option, depending on what he's doing.

Let's say we are net metering in a 240Vac, 20 Amps, 60 Hz power line in a digital power meter.
Cheers, Harry

Then what I posted applies, including the suggestion to use a power metering
chip. I'm sure they have plenty of app notes too.

You have two hot wires coming in, yes? Look at that at any instant in time
when there is voltage, ie not when it's crossing zero and you have
what looks like a DC voltage, yes? One wire is positive, one negative, yes?
Measure the direction of the current in the positive wire. The current
will be flowing on the positive wire from the source to the load.
The power metering chips do that and compute the voltage, current,
power, etc on the fly.

 

[Whoey Louie]

On Thursday, August 29, 2019 at 4:33:13 PM UTC-4, Whoey Louie wrote:

On Thursday, August 29, 2019 at 3:26:40 PM UTC-4, Harry D wrote:
On Tuesday, August 27, 2019 at 5:32:59 PM UTC-7, Phil Allison wrote:
Harry D wrote:

------------------


Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?

If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.


** A current transducer (or transformer) will give you an easily read and SAFE voltage analogue of the actual current.

The easiest way to identify which way it is flowing is to use a scope in X-Y mode - with voltage and current waves on each input.

For in-phase waves, the slope of the line on the screen will be opposite in each case.



.... Phil
.... Phil

I need this circuit for a Power Meter that will do net-metering in a 20A, 240 Vac 60 Herts power line. It will have a digital readout.
Cheers, Harry



Why reinvent the wheel? Buy a digitial power meter. Or if you need to
build, then a power metering chip, and a lot of other components, it's
not trivial. That chip will multiply voltage by current in real-time
to get the power. Without doing that, if say you measured voltage with
one circuit or instrument, current with another, you won't know the power unless
you also know the phase relationship between the current and voltage
and that it doesn't vary. If it's a resistive load, that isn't an issue,
but if it's typical loads for a net metering application, eg non-incandescent
lighting, motors, appliances with power supplies, then the voltage and
current will not be in perfect phase and it changes.

Also take a look on Ebay, there are power measuring modules for sale there
starting at $5. IDK what they are rated for, nor what you're doing, so
proceed at your own risk.

 

[Whoey Louie]

On Thursday, August 29, 2019 at 3:13:46 PM UTC-4, Harry D wrote:

On Tuesday, August 27, 2019 at 4:04:15 PM UTC-7, John Larkin wrote:
On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2kx@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

Grid voltage can be constant so I still have the problem of measuring the voltage difference across a sense resistor in a 250 V CM. That is difficult to do with a 60 Hertz power line. Averaging will help but there has got to be a better way. I have the same problem with the CT.
Cheers, Harry

What's so hard about measuring the voltage across a resistor? That isn't
the hard part. The hard part is measuring the voltage and current at each
point in time, multiplying it and integrating it to get power and energy.
Which is why I said use a power metering chip.

 

On Thu, 29 Aug 2019 12:13:41 -0700 (PDT), Harry D <td2k99@gmail.com>
wrote:

On Tuesday, August 27, 2019 at 4:04:15 PM UTC-7, John Larkin wrote:
On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2kx@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

Grid voltage can be constant so I still have the problem of measuring the voltage difference across a sense resistor in a 250 V CM. That is difficult to do with a 60 Hertz power line. Averaging will help but there has got to be a better way. I have the same problem with the CT.
Cheers, Harry

A standard CT will output 5 amps. You could get a 20:5 or 40:5 CT,
something like that. It would dump into a burden resistor, and give
you a big, isolated, legally insulated signal.

There are also DVM accessory clamp-on current transformers, which
output a scaled voltage.

You still need to include the line-line voltage to determine the
direction of power flow. There are power meters that do that.

https://www.amazon.com/Current-Amperage-Voltmeter-Multimeter-Transformer/dp/B07JB9B2QL/ref=sr_1_16?keywords=clamp-on+power+meter&qid=1567128783&s=gateway&sr=8-16

 

[piglet]

On 29/08/2019 20:13, Harry D wrote:

On Tuesday, August 27, 2019 at 4:04:15 PM UTC-7, John Larkin wrote:
On Tue, 27 Aug 2019 14:59:05 -0700 (PDT), Harry D <td2kx@gmail.com
wrote:

Let's say we have +/-20 Amps of AC current flowing at 250V into (Source) or out of (sinking) a node. (The node is the grid and we can either supply or sink current to that node). Measuring current is easy but how do I determine which direction it is going. Am I sourcing or sinking?
If I sense the differential voltage across a 1mR sense resistor, limiting my power loss to 0.40 watts, and trying to resolve a 100 mA current change in direction, my CMRR would be -128 DB, not easy to do. There has got to be a better way.
Cheers, Harry

AC current doesn't really have a direction at one point on a wire.

Power does. To measure power magnitude and sign, you need to measure
both voltage (relative to a return wire) and current and
multiply+average, or equivalent.

The usual way to measure AC current is with a current transformer.

Grid voltage can be constant so I still have the problem of measuring the voltage difference across a sense resistor in a 250 V CM. That is difficult to do with a 60 Hertz power line. Averaging will help but there has got to be a better way. I have the same problem with the CT.
Cheers, Harry

I have dissected two electronic utility meters (different makes) and
neither had any wound components. Current measurement was by hall effect
chip clamped to the current carrying busbar with magnetic circuit closed
by some magnetic material. Voltage by a string of high value resistors.

piglet

 

On Friday, 30 August 2019 11:36:54 UTC+1, piglet wrote:

I have dissected two electronic utility meters (different makes) and
neither had any wound components. Current measurement was by hall effect
chip clamped to the current carrying busbar with magnetic circuit closed
by some magnetic material. Voltage by a string of high value resistors.

piglet

I have seen the innards of a meter at the UK factory where it was
being made. It sensed current with a 4-terminal resistor which was
a short strip of manganin electron-beam welded to copper busbars
in a 4-terminal configuration. The voltage drop across the
current sense resistor was amplified with an op-amp. The mains voltage
was divided down with a series string of resistors. The rest of
the work was done with a microcontroller.

John

 

[whit3rd]

On Thursday, August 29, 2019 at 1:33:13 PM UTC-7, Whoey Louie wrote:

> Why reinvent the wheel? Buy a digitial power meter.

The mount-on-the-exterior power meters of yore were human-readable.
The modern digital ones I see are... much less friendly to
a user, and favor networked operation by power utilities.

What, exactly, would be a good model of such a meter (to fit
a standard meter base) for an end user? Landis and Gyr have a
bunch of offerings, but trying to figure out accuracy and whether the
current can be indicated, is gonna take some work (they MUST have
a document somewhere, but I'm not seeing details on the website).

 

[Whoey Louie]

On Friday, August 30, 2019 at 1:10:09 PM UTC-4, whit3rd wrote:

On Thursday, August 29, 2019 at 1:33:13 PM UTC-7, Whoey Louie wrote:

Why reinvent the wheel? Buy a digitial power meter.

The mount-on-the-exterior power meters of yore were human-readable.
The modern digital ones I see are... much less friendly to
a user, and favor networked operation by power utilities.

What, exactly, would be a good model of such a meter (to fit
a standard meter base) for an end user? Landis and Gyr have a
bunch of offerings, but trying to figure out accuracy and whether the
current can be indicated, is gonna take some work (they MUST have
a document somewhere, but I'm not seeing details on the website).

IDK, good points. I didn't mean to necessarily buy the kind of bulky
power meter that plugs into a meter base. Those, I agree, not clear
that most or any would display amps or even anything other than Kwh.
But some of them probably have some kind of interface to transmit
real-time data, what with all the solar folks wanting to monitor
their solar array and such.

I had pointed him to Ebay and something like this is more what I had
in mind:

271952136069

That's the item number, just put that into the Ebay search bar.
The link was a mile long. It's $13 and they've sold 3100 of them.
Not much info on it there though, but it sure looks nice and it
shows volts, amps, power and energy, rated at 100A, 260V. It shows
it wired directly up to a load. How that widget handles 100A, IDK.

But if not that, then I bet there are other off the shelf modules
that do what he wants.

 

[Whoey Louie]

On Friday, August 30, 2019 at 2:17:40 PM UTC-4, Whoey Louie wrote:

On Friday, August 30, 2019 at 1:10:09 PM UTC-4, whit3rd wrote:
On Thursday, August 29, 2019 at 1:33:13 PM UTC-7, Whoey Louie wrote:

Why reinvent the wheel? Buy a digitial power meter.

The mount-on-the-exterior power meters of yore were human-readable.
The modern digital ones I see are... much less friendly to
a user, and favor networked operation by power utilities.

What, exactly, would be a good model of such a meter (to fit
a standard meter base) for an end user? Landis and Gyr have a
bunch of offerings, but trying to figure out accuracy and whether the
current can be indicated, is gonna take some work (they MUST have
a document somewhere, but I'm not seeing details on the website).

IDK, good points. I didn't mean to necessarily buy the kind of bulky
power meter that plugs into a meter base. Those, I agree, not clear
that most or any would display amps or even anything other than Kwh.
But some of them probably have some kind of interface to transmit
real-time data, what with all the solar folks wanting to monitor
their solar array and such.

I had pointed him to Ebay and something like this is more what I had
in mind:

271952136069

That's the item number, just put that into the Ebay search bar.
The link was a mile long. It's $13 and they've sold 3100 of them.
Not much info on it there though, but it sure looks nice and it
shows volts, amps, power and energy, rated at 100A, 260V. It shows
it wired directly up to a load. How that widget handles 100A, IDK.

But if not that, then I bet there are other off the shelf modules
that do what he wants.

Never mind how it handles 100A, it shows a schematic with a CT and it
includes one.

Another thought, I wonder how that cheap module handles the power direction?
Does it show positive or negative for the current/power? Details like that
are always a problem with that Chinese cheap stuff. You'd think it
probably does because they are using some kind of power meter IC that
should be capable of that, would do it automatically. Doesn't cost much
to try it though, compared to building one.....