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24v DC offset into AC Mains supply, RMS 230V 50 Hz
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Bill8989:
Hi, is it possible to put a 24v dc offset into a 50Hz 230v AC supply and then remove it at another point such as a wall socket?
If so how do I work out the values of the capacitors and inductance needed?
Zero999:
Just one question: why?

It's possible, but is a very bad idea and probably violates some wiring regulations. DC will cause a very high current to flow through transformers and AC motors, causing them to overheat.
DenzilPenberthy:
Short answer: No.

Mains live & neutral have a very low DC impedance between them - well under an ohm typically. The supply cables and the secondary winding of the distribution transformer are very chunky copper!

Feeding DC through AC transformers is a bad idea. It can saturate the core which then blows up the transformer.

Perhaps the idea you have in mind is a bias-T  arrangement. This is common for adding a DC bias to RF signals.  You won't like the values of L and C you will need though for it to work at 50Hz!!!

https://en.wikipedia.org/wiki/Bias_tee
Bill8989:
Perfect, this is what I was looking for, Bias tee.
If you're wondering why I'm asking, its a university project. The concept is to produce solar power DC and avoid using an inverter to go from ac-dc then to step back down to DC to power Dc appliances
I know it's very unlikely to work but I can scale it down to 25vac find a doable freq and compare the values from the formulas to explain why it doesn't work and compare the efficiencies.

Thanks for the response.
Zero999:

--- Quote from: Bill8989 on December 06, 2019, 10:41:10 am ---Perfect, this is what I was looking for, Bias tee.
If you're wondering why I'm asking, its a university project. The concept is to produce solar power DC and avoid using an inverter to go from ac-dc then to step back down to DC to power Dc appliances
I know it's very unlikely to work but I can scale it down to 25vac find a doable freq and compare the values from the formulas to explain why it doesn't work and compare the efficiencies.

Thanks for the response.

--- End quote ---
You'll need a massive inductors and capacitors for it to work at mains frequencies.

You've also missed the point about transformers and motors. If someone connects a fridge to the mains, with a 24VDC bias on it, the motor will overheat. It's a very bad idea.

If you need to power DC appliances, then simply run a separate cable carrying DC.
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