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Difference between Vdc and Vrms

#21
A couple of errors in that statement:
It should say
325 V PEAK = 230 V RMS

Similarly the statement:

Should say
VAC peak /square root of 2 = VAC RMS


Peak to peak is twice the value of peak.
All this applies to a sine wave.
If the waveform is not a sinewave, all bets are off.

JImB
I really hate it when someone finds the 5% not important mistakes like "320" and "325"..... My statements are fully accurate!
 

JimB

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#22
OK, I agree that 5% is splitting hairs, but the big error is confusing "Peak" with "Peak to Peak".

In the interests of complete accuracy I amended the 320v to 325v.

My statements are fully accurate!
No they are not, as written they are in error by a factor of 2.

JimB
 

Nigel Goodwin

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Most Helpful Member
#23
Why do you think so? All europe uses this voltage. (I don´t count UK, since it is very soon to be somewhere in the middle of the atlantic ;) )
NO they don't use 230V - which is why it bugs me :D

Mainland Europe uses 220V and the UK uses 240V, just as they have done for many decades.

The 230V specification ISN'T for mains, it's a mid-voltage specification for EQUIPMENT only, which is to ensure it works on both the 220V and 240V mains systems. The 230V equipment specification deliberately includes the top and bottom ends of the 220V and 240V mains systems, the only change was to the tolerences required, previously they were symmetrical, now they aren't - the 220V tolerance was moved upwards, and the 240V one downwards.
 

JimB

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#26

audioguru

Well-Known Member
Most Helpful Member
#27
In fact, a 1 volt peak sine wave outputs only 70.7% of the power a 1 volt constant amplitude source would produce.
No. 1V peak is 0.707 times the voltage (not the power) that a 1VDC would produce. (0.707V squared)/1 ohm= 0.5W. But (1V squared)/1 ohm= 1W. That is why a poor quality amplifier states the peak or maximum power that is double the real RMS power number.
 

Ratchit

Well-Known Member
#28
No. 1V peak is 0.707 times the voltage (not the power) that a 1VDC would produce. (0.707V squared)/1 ohm= 0.5W. But (1V squared)/1 ohm= 1W. That is why a poor quality amplifier states the peak or maximum power that is double the real RMS power number.
Correct, I forgot to take the square of 0.707.

Ratch
 

unclejed613

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Most Helpful Member
#31
somewhere i recall seeing a chart of the relationships of commonly used methods of measuring voltage (average vs RMS vs Peak vs Peak-to-Peak) and the conversion factors. all of them were also shown for sine, square and triangle
 

Ratchit

Well-Known Member
#32
somewhere i recall seeing a chart of the relationships of commonly used methods of measuring voltage (average vs RMS vs Peak vs Peak-to-Peak) and the conversion factors. all of them were also shown for sine, square and triangle
Easy to calculate if you specify the waveform and what factor is desired.

Ratch
 

Nigel Goodwin

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Most Helpful Member
#34
That is not true, at least here it is specified as 230V+/-10%, same is in Germany, and in my socket is 233V.
Last I heard the mains voltage in Germany was 'nominally' 230V +6%/-10%, same as other 220V countries, and the specification for equipment (for all of the EU) was 230V +/-10%. The UK is 'nominally' 230V -6%/+10%, and nothing changed, it's still 240V as usual - no need to change, the spec was designed so as not to require any changes.

The plan was to alter the mains specifications for all the EU to 230V +/-10% - which is just widening the specification, and requires no changes to the mains voltages in any of the countries.

If your socket reads 233V then that falls well within either of the 220V area tolerances.
 

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