12V 80Va Transformer

"Ian Tedridge" schreef in bericht news: snipped-for-privacy@bt.com...

You can get 80/24=3.3A out of it when 12V outputs in series or 6,6A when in parallel. This applies for a constant load, regardless of the phase angle. When using rectifiers you have to use a correction factor.

petrus bitbyter

So why would anyone use the outputs in series?

12V

pull

in

To get the desired voltage.

To get 24 volts???

Those outputs will each 'share' the 80VA i.e. 40VA each.

So each winding is good for 40/12 A = 3.33A

In parallel that'll supply 12V @ 7.66A.

In series it'll supply 24V @ 3.33A.

Graham

Why would anyone answer such a stupid question ?

Graham

ooops typo ^^^^^ 6.66 A

"Ian Tedridge"

** It means the transformer will *continuously* supply 80 VA into to a load while remaining at a safe operating temperature - providing:

1. The load VA is divided evenly between the two 12 volt secondary windings.
2. The AC load current is symmetrical about + and - values, ie no half wave rectification is involved.

Note:

VA = total * rms * load current x rms voltage (12 or 24 in this case)

........ Phil

Because this is the place for stupid questions, and petrus bitbyter didn't mention the 24 volts in his original reply. He, however seems legitimately interested in using this place to discuss electrical questions, and not as a place to get frustrated.

80VA / ( 12A * 2 ) about 3.33A

usually, yes, but don't get one of them backewards. that'd be about 6.66A Bye. Jasen

He did actually ( in an equation ) , but it went right over your dumb head.

Graham

With most kinds of ( typically capacitor input ) rectification to DC - the current waveform crest factor / conduction angle influences the effective VA rating though. I.e. derate for equivalent DC watts. Or looking at it another way Irms is not equal to the normalised Iav for a sinewave.

Graham

"Eeyore"

** All TOTALLY covered by the VA figure since the definition of " VA " REQUIRES the * rms * value of the load current to be used.

I must posted this at least 50 times on usenet .

So no f****ng need to tell me - you pommy nerd.

BTW

Is the change of name a public admission you are bipolar ?

...... Phil

I appreciate that *you* know it but I'll bet many ppl think you can draw the same 80W DC from a capacitor input rectifier connected to the same transformer.

Not many ppl own true rms meters either btw.

Nope. It was actually an indirect response to a nitwit in another group. It amused me. Feel free to say I'm easily amused btw.

Graham

"Eyesore"

** THEN DO **NOT** FUCKING POST IT TO ME !!!!!!!!

POST IT TO THE BLOODY OP

NOT UNDER MY WORDS - FUCKWIT !!

** Shame.

........ Phil

"jasen"

( snip yet another ASININE copy cat post)

** FUCK OFF !!!!!!!!!!!

you PITA, f****ng KIWI COPY CAT

.......... Phil

--- Aren't you that same stupid, top-posting sonofabitch who made a complete ass out of himself in that "downed powerline" thread?

Geez, it seems like you'd have learned by now that nobody wants to read your shit.

That's right. NOBODY. So why are you hanging around? Do you _like_ abuse or is it the only way you can get any attention?

Fucking idiot.

-- John Fields Professional Circuit Designer

--- No, this is supposed to be the place where there _are_ no stupid questions.

Stupid _posters_, however, are another matter, and you seem to be leading that pack by leaps and bounds.

Learn to bottom post, dumbass.

-- John Fields Professional Circuit Designer

I think you're being a teensy bit too sensitive here Phil. It wasn't meant as a correction but an addition to what you said.

Graham