Peek to Peek Voltage at 220 volts AC 50-60 Hz - Page 1
Forum section: electronics / beginners

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 24, 2013, 01:04:27 am
content: Hello i got a questioni saw a topic about RMS and Peek to Peek voltage and an answer was reffered to peek to peek as the value between the highest and the lowerst AC voltage........(i suck at explaining the answer i know)Does that mean that the peek to peek voltage of 220 voltas AC is 440 volts???+ 220 volts (highest value of AC220)- 220 volts (lowest value of AC220)So the peek to peek volage is given by this| lowest value | + highest value = peek to peek votlagebut something says to me that the peek to peek volage is 220 volts which of these is the right one.

author: Rerouter
author_rank: Super Contributor
timestamp: March 24, 2013, 01:18:24 am
content: but higher than that, that 220V is rms voltage, which comes to +-312V peak (220/0.707), so peak to peak is 624V

author: Monkeh
author_rank: Super Contributor
timestamp: March 24, 2013, 01:18:38 am
content: None of those is correct.220VAC (or 230VAC, or 240VAC, or the silly 120VAC system the yanks like, etc) is a RMS voltage, not a peak voltage, of a 50Hz or 60Hz sine wave. Here, have a picture:The peaks (1) of a 220VAC RMS sine wave are approximately 310V above and below the zero point. The peak-to-peak voltage (2) is 620V.

author: Monkeh
author_rank: Super Contributor
timestamp: March 24, 2013, 01:32:38 am
content: Quote from: IanB on March 24, 2013, 01:31:22 amHe posted that as I was typing, I was 14 seconds slow.And no, the answer is whatever it is at the time you get the waveform and properly calculate it as it's not really sinusoidal

author: IanB
author_rank: Super Contributor
timestamp: March 24, 2013, 01:34:53 am
content: Quote from: Monkeh on March 24, 2013, 01:32:38 amI know, I deleted my post as I realized that after posting...

author: Monkeh
author_rank: Super Contributor
timestamp: March 24, 2013, 01:35:28 am
content: Quote from: IanB on March 24, 2013, 01:34:53 amSee, now you're just confusing people!

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 24, 2013, 01:35:43 am
content: First of all I AM SO SORRY FOR THE SPELLING MISTAKE(peek) i mean peak to peak voltage as you understoodAlso thank you very much for this but i am still confused...

author: IanB
author_rank: Super Contributor
timestamp: March 24, 2013, 01:40:42 am
content: Quote from: ChrisGreece52 on March 24, 2013, 01:35:43 amThe mains voltage (e.g. 220 V) is an average voltage. It varies with an alternating cycle. Sometimes the voltage is higher than the average, sometimes the voltage is zero, and sometimes the voltage is reversed.The peak-to-peak voltage is the difference between the highest forward voltage (+311 V) and the lowest reverse voltage (-311 V), giving a total difference of 622 V. However, both forward and reverse voltages are referenced to earth or ground potential, so the highest magnitude you will be able to see is 311 V.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 24, 2013, 01:47:07 am
content: Quote from: IanB on March 24, 2013, 01:40:42 amThanks i got it nowsr English is me seconds language (Greek being my native) so i can get a bit confused.

author: nerdyHippy
author_rank: Contributor
timestamp: March 24, 2013, 05:20:11 am
content: Quote from: IanB on March 24, 2013, 01:40:42 amThis is true, but may be slightly misleading, as "average" in this sense isn't defined as a mathematical mean. The mean voltage of a pure AC signal is 0V, butthis doesn't convey any information about the signal in question. As a fix, you can square the signal (which removes all negative components) take the mean of this, then take the square root of the resulting signal.

author: digsys
author_rank: Unknown
timestamp: March 24, 2013, 05:36:58 am
content: To expand on IanB - MOST equipment ie Transformer / switcher, will never SEE ~622V, it will ONLY see ~311V Peak.The +ve and -ve cycle can not exist together (to be precise - separately as a Voltage or Current)The RMS AC Voltage is the equivalent DC Voltage that will have the Same Energy V*I (ignoring the messy phase issue :-))

author: AlfBaz
author_rank: Super Contributor
timestamp: March 24, 2013, 06:17:29 am
content: Quote from: digsys on March 24, 2013, 05:36:58 amThe set of circumstances around the experience I had in the following, convolute the matter and in no way demeans what you stipulate but I thought I'd share the story as its not something you encounter every day.I use to do work on ships that frequented our local harbour. The majority of them had 3 phase 415V alternators with no MEN link or anything else connected to the star point (I think yanks call it "Y")240V for general purpose outlets was generated via a 3 phase transformer so all 240 was 3 phase, ie both lines in an outlet were active and thus all AC switching had to be 2 pole.At any rate I was asked to investigate an outlet that seemed to be playing up (cant remember the symptoms) but I measured the 2 actives and got 240V between them and in excess if 600VAC to earth on one of them... WTF?!?!Turns out one of phases for the 415V was very low to earth and like wise with a different 240V phase. Found the offending cct's, cleared the earths and all was good

author: vk6zgo
author_rank: Super Contributor
timestamp: March 24, 2013, 08:26:12 am
content: The point to remember with an AC signal is that peak-to- peak is not arealthing,as the negative & positive half cycles arenotpresent at the same time.It exists primarily so that if you take a "peek" at the waveform with an Oscilloscope.you have a convenenient measurement to comparewith other readings,so you may for instance, read 20mV p-p & adjust it to 50mV p-p,without having to calculate the actual peak or RMSvalues.Peak to Peak is also used,when AC & DC signals are combined,for instance, the input circuit of a particular amplifier may need to go between +2v to -2V without being either clipped by the input circuitry or driving the output device into clipping.The only "Peak" voltage you need to think about when dealing withnormalsingle phase 220V AC circuits is the peak voltage inany half cycle.RMS is the same value as that DC voltage which would need to be used to dissipate the same power in the same load resistance as that achieved using an AC supply.A classic method is to heat some water electrically---good old 19th Century technology!As has already been pointed out,V peak for VRMS of 220v is,near as dammit,311V.

author: M. András
author_rank: Super Contributor
timestamp: March 24, 2013, 09:35:31 am
content: just measured the line voltage on this phase which comes in my room, 215v and peak +-289or 285? forgot it

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 24, 2013, 04:39:11 pm
content: Quote from: digsys on March 24, 2013, 05:36:58 amThanks for making it clear

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 24, 2013, 04:40:43 pm
content: Thanks to your replies i got the meaning of peak to peak voltage.