Electricity (and Shocks)

[Crossy]

LOL, so AC mains is 622v peak to peak, did they really teach you that........................it's all relative to ?????????

220VAC is the RMS value, converting from RMS to Peak = 220 x 1.414 = 311V and peak to peak is 311 x 2 = 622.

Unless I'm not understanding what you are saying, I'm having trouble with this.

How does a 2 wire AC service swing to negative? Negative compared to what? This says it better than I could .. although it's about 110 vs 220, but all else is the same .. except frequency.

"The 115 to 120 Volt household AC voltage actually swings

sinusoidally (or smoothly) from zero volts to a peak of about

165 Volts, then back to zero and continues to a peak of -165

Volts and back to zero again. It repeats this 60 times a

second here in North America."

I believe 622 V P-P would get you 440.

I may be wrong .. but that's nothing new.

The RMS value is .7071 x the PEAK (not PEAK TO PEAK) value.

If you use one wire as a reference point (the neutral) then the other alternates sinusoidally between +311 V and -311V relative to that reference.

Since the mean (average) value of a sine wave is actually zero, we square each value (which makes them all positive), then take the square root of the mean, hence RMS = Root Mean Square, which rather conveniently has the same energy content as a DC voltage/current of the same value, handy for making the sums easy.

NOTE This only applies for resistive loads (incandescent lights, heaters etc.), motors and fluorescent lights introduce a nasty effect known as Power Factor caused by a phase difference between the voltage and current, which reduces the actual amount of power (Watts) relative to the Apparent Power (Volts x Amps or VA). Which is why your 1000VA UPS can actually only provide 800Watts or even less.

Interesting paper form APC http://www.apcmedia.com/salestools/SADE-5TNQYF_R0_EN.pdf

Edited December 17, 2007 by Crossy

[gharknes]

LOL, so AC mains is 622v peak to peak, did they really teach you that........................it's all relative to ?????????

220VAC is the RMS value, converting from RMS to Peak = 220 x 1.414 = 311V and peak to peak is 311 x 2 = 622.

Unless I'm not understanding what you are saying, I'm having trouble with this.

How does a 2 wire AC service swing to negative? Negative compared to what? This says it better than I could .. although it's about 110 vs 220, but all else is the same .. except frequency.

"The 115 to 120 Volt household AC voltage actually swings

sinusoidally (or smoothly) from zero volts to a peak of about

165 Volts, then back to zero and continues to a peak of -165

Volts and back to zero again. It repeats this 60 times a

second here in North America."

I believe 622 V P-P would get you 440.

I may be wrong .. but that's nothing new.

actually you are correct, someone else is blowing out their other place.

crossey

Also getting a ground on the 20th floor of a condo building is difficult when none is provided, yes you could ground everything to neutral but relative to your floor etc there may be some potential difference, this will have the effect of give minor shocks with most things you touch while in bare feet, a friend of mne couldn't use his mic while bare footed, it showed live on a neon mains tester, ref points and potential difference are important, I suppose you would also know that the potential in a mains supply is in fact the neutral and not the live, electricity is pulled or drawn not pushed,mains potential is in the ground., also mains voltage although alternating does not go below zero volts so it is not -311 to +311 which are incorrect values anyway. 0-311 will give you 220 rms, also AC simply means alternating, the alternating voltage depends on reference to what, I used to work on switch mode power supplies that actually converted DC to AC then back to several outputs of DC again (quite complex stuff) voltage regulation and current protection was controlled by the various frequencies of the AC, a -12 +12 output was provided by +24 developed across two windings of a transformer center tapped as reference, want me to continue ??

PS when someone says that someone on this forum is not quite correct try not to reduce to personal insults people

Edited December 17, 2007 by gharknes

[Crossy]

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Edited December 17, 2007 by Crossy

[Tywais]

actually you are correct, someone else is blowing out their other place.

PS when someone says that someone on this forum is not quite correct try not to reduce to personal insults people

I think this is quite enough of the bickering and aggressive postings. And before someone gets penalized >>

[klikster]

I used to work on switch mode power supplies that actually converted DC to AC then back to several outputs of DC again (quite complex stuff) voltage regulation and current protection was controlled by the various frequencies of the AC, a -12 +12 output was provided by +24 developed across two windings of a transformer center tapped as reference, want me to continue ??

PS when someone says that someone on this forum is not quite correct try not to reduce to personal insults people

I can actually go you one .. um .. older.

In my high school days I worked in a radio-TV shop. That was back during vacuum tube days. Tubes wouldn't work on 6 volts (old car batteries) or 12 volts, so car radios had 'vibrators'. Basically a vibrator was an electro mechanical device that chopped the 6 VDC so a transformer would work .. not sure about the frequency. The xformer stepped up to around 150 v then got rectified and filtered back to dc.