capacitances in parallel

Jan 03, 2007 50 Replies

That's an interesting way of thinking of them - the energy stored function defines the connection required for them to retain their energy

So:

e = 1/2CV^2 -> maintain the voltage

e = 1/2LI^2 -> maintain the current

Cheers

PeteS

While both store energy, and it IS possible to come up with various scenarios involving superconductors and the like wherein inductive storage would work "in isolation," I think that in a practical, real-world sense this IS a significant difference between capacitors and inductors. After all, how many "super-inductors" do you see being used, essentially, as batteries? :-)

Bob M.

There have been some plans for, and small-scale prototypes of, superconductive electrical energy storage facilities. Google "superconductive energy storage" for lots of interesting stuff.

I've never heard of capacitors being considered on this scale.

John

short the leads... that's how the make superconducting magnets....

Bye. Jasen

"jasen"

** No wonder NZ is the one place every inhabitant wants to split.

Just to escape the F****NG " jasen " IDIOTS for one reason !!!

Then there are all those tattooed, psycho Maoris ........

...... Phil

Yeah, sure, but I wouldn\'t think "in isolation" included the cooling equipment.

Good grief, you really *don't* understand inductors!

John

The magnets don't have cooling equipment as such, just insulation.

So hang it out in deep space, where the blackbody temperature is 4K. Is that "isolated" enough?

John

[a load of s*it]

A candidate for Google Groups Killfile

formatting link

It works on Firefox including 2.0. You need Greasemonkey. I'm not sure if it can be used with IE or Opera.

Bye Phil!

** A candidate for Google Groups Killfile

Or else any convenient tree and a long rope.

....... Phil

"John Farkin Idiot "

** What an ASD f***ed f****it.

....... Phil

You really aren't very good with insults, either. What *are* you good at?

John

"John Farkin Idiot "

** What a BORING ASD f***ed f****it.

....... Phil

I'll take that for "nothing."

John

"John Farkin Idiot "

** What a BORING ASD f***ed f****it.

They sure don't like being outed

This cretin is just burning with indignant rage.

........ Phil

Take it out past Pluto... pretty isolated out there and plenty cold enough.

Bye. Jasen

** ROTFLMAO !!

The Wanker King of Usenet Plaigerism strikes again !!!!!

No wonder NZ is the one place every inhabitant wants to split.

Just to escape all the F****NG " jasen " IDIOTS for one reason !!!

Then there are all those tattooed, psycho Maoris about to out vote the asinine, d*****ad, failed pommies that think they own the s*it hole ........

...... Phil

--- Goddam, John, why are you always so ornery?

Here: On Earth, you can take a capacitor, charge it up, remove the supply and the "isolated" cap will stay charged up forever, neglecting leakage.

Can you do the same thing with an inductor? Not unless you make it superconducting, which requires ancillary equipment, which takes it out of the 'isolated' category.

Yes, it would work in space at 4K. So what?

-- JF

Yes. The current will circulate forever, neglecting resistive losses. No different from a cap. At room temp, caps can have longer decay tau's than inductors. The biggest real-life, non-superconducting L/R time constants I've heard of were in the few-hours sort of range.

So inductors store energy "in isolation" just like caps do. And utility-scale inductive energy storage is feasible.

John

Yes, but you can\'t neglect the resistive losses without making the inductor superconductive, and to do that you have to have to make, and keep, the inductor superconductive. That keeps it from being "in isolation", a criterion the simple charged cap easily meets.

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