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Transformer phase angle error
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wraper:

--- Quote from: Jester on December 19, 2018, 11:20:15 pm ---
--- Quote from: wraper on December 19, 2018, 10:01:54 pm ---Why cannot you make measurment on the primary side and then transfer data via optoisolator? This is how bench multimeters work. IMHO you are trying to invent the wheel.

--- End quote ---

Well we could but that would be like reinventing the wheel,  when you can purchase a 0.1% accurate Energy Metering IC for $1

https://www.digikey.com/products/en/integrated-circuits-ics/pmic-energy-metering/765?FV=ffe002fd%2Cbfc0002&quantity=0&ColumnSort=1000011&page=1&pageSize=25

--- End quote ---
And what's the problem placing it on high voltage side?
wraper:
LOL, did you bother to read the datasheet? It's freaking intended to sit on mains voltage side  :palm:. And you telling me you are not reinventing the wheel.



djacobow:
if it's power measurement, consider using a chip designed for the job. My adventures with the atm9e26 are well-documented on this forum. That particular chip lives on the mains side, uses a voltage divider for voltage and a shunt or a CT for current. I only used a shunt, though I suspect that the phase error with a CT is lower than for a power transformer, since they are intended specifically for this type of instrumentation.

One problem I did have with my project (still do) is lack of proper equipment to calibrate it. If you want a 1% instrument and it needs to perform that accurately even at very low power factors, you're probably going to want a lab quality programmable AC load, and maybe AC source, too.
Jester:
Wraper,

I was not asking for advice on how to design a circuit, it was a simple question about phase delay across a transformer. We were designing optically isolated circuits running on the high side decades ago. I'm not at liberty to share the details of the specification that we're working to, I can tell you that it must have a transformer, even if there may be better approaches. BTW I did read the data sheet and have 10's of thousands of a design that is running resistor coupled inputs that have been in the field for years.

Have a nice day, no need to respond as none of what you have posted as been the least bit useful.
wraper:

--- Quote from: Jester on December 20, 2018, 01:35:17 am ---Wraper,

I was not asking for advice on how to design a circuit, it was a simple question about phase delay across a transformer. We were designing optically isolated circuits running on the high side decades ago. I'm not at liberty to share the details of the specification that we're working to, I can tell you that it must have a transformer, even if there may be better approaches. BTW I did read the data sheet and have 10's of thousands of a design that is running resistor coupled inputs that have been in the field for years.

Have a nice day, no need to respond as none of what you have posted as been the least bit useful.

--- End quote ---
Your post about ICs and link suggested exactly opposite. Providing link to ICs which are supposed to sit on the mains side and use isolators, just as I suggested. From the beginning I felt you want to do something fishy. And none of what I asked was anything too specific. Yet you gave useless answers instead of just saying it's confidential. And the fact you are going to use usual small transformer and expecting achieving better than 1% accuracy shows you have no clue what you are doing. You might somewhat get it with particular transformer but when that gets into mass production, don't expect anything good. Also don't expect it working well over wide temperature range.
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