If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Capacitors aside, half of a full wave doubler has to look to comparing RMS watts in to Average watts out. Sin wave, starting to peak its (.707 *peak /2) * I Rms watts in = (.318 * peak) * I Average watts out. As capacitors are added to reduce ripple the input current waveform changes from Sin to approach square.
So the output statement has to include the ripple.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
The "thermal converter" measures watts. If the 60 Hz current has a sin waveform, then the product of the voltage * current* cos (phase angle) will be watts, and the voltage be measured in RMS volts. As such, that instrument cannot indicate peak watts because peak watts would imply peak heat. Because it has two transformers, it cannot indicate average watts. So what is left? RMS watts.
Registered Member #2481
Joined: Mon Nov 23 2009, 03:07PM
Location: ITALY
Posts: 134
radiotech wrote ...
The "thermal converter" measures watts. If the 60 Hz current has a sin waveform, then the product of the voltage * current* cos (phase angle) will be watts, and the voltage be measured in RMS volts. As such, that instrument cannot indicate peak watts because peak watts would imply peak heat. Because it has two transformers, it cannot indicate average watts. So what is left? RMS watts.
Wasn't the renowned James Watt from Scotland?
RMS watt has no physical meaning...
Power can be either instantaneous or average, but NOT rms...
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Generators are rated in mVA because that represents the sizing of conductors needed. The power output is is in mW and is sold as that. It has been the custom for ages to run those with a power factor, however with energy so expensive these days that is being rethought,
Luca said : Power can be either instantaneous or average, but NOT rms...
If you are starting with a sin wave, as the point of this thread is, and want to know the efficiency of the converter, the wattmeter measuring the input will be calibrated in RMS volts * Amps * pf
Why the thermal wattmeter is suggested, is that it will measure the thermal equivalent, in watts of the power in.
To get at the power input easily, a thermal ammeter could be used with a RMS voltmeter. They can be had if searched for.
The fact that RMS Watts are not equivalent to Thermal Watts is correct. These things measure I^R in both halves of waveform.
The RMS voltage * current (resistive) ends up at the same level of power.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
RMS volts * RMS amps * PF is real power, measured in watts. Watts are work done per unit time, hence always an average quantity. There is really no such thing as "instantaneous" power. I guess the term is used loosely, to mean work done in a very small unit of time, in the same sense as "infinitesimal" in calculus.
Note that there are two kinds of power factor: displacement power factor, which is the regular "cos phi" kind, and harmonic power factor, which is the result of the voltage and current waveforms having different shapes, even if they are in phase.
Any decent wattmeter should take account of both power factors, and tell you the real power passing through it, in the thermodynamic "rate of work" sense.
RMS volts * RMS amps is apparent power, measured in VA.
If you take the vector difference of your apparent power and your real power, what you have left is reactive or imaginary power, which has a time average of zero, hence technically doesn't exist at all.
There is no such thing as RMS or thermal watts. Well, maybe in North America where they measure air conditioning in tons, gravity in slugs per square fortnight and so on.
Registered Member #2481
Joined: Mon Nov 23 2009, 03:07PM
Location: ITALY
Posts: 134
Steve McConner wrote ...
RMS volts * RMS amps * PF is real power, measured in watts. Watts are work done per unit time, hence always an average quantity. There is really no such thing as "instantaneous" power. I guess the term is used loosely, to mean work done in a very small unit of time, in the same sense as "infinitesimal" in calculus.
Istantaneous power = limit Dt-->0 DW/Dt where W is work and t is time...
However, I agree that the most meaningful way to represent power is the "average" value, but definitely not the rms value.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
If you take the vector difference of your apparent power and your real power, what you have left is reactive or imaginary power, which has a time average of zero, hence technically doesn't exist at all.
The truck and trade of a power dispatcher in pre-computer days was to move megawatts and megavars (mW and mVA) around the system. It was common to think of reactive power as a quantity moving from one place to another when the controls for both the generation and the load side of machinery were in one place. Once the power factor had been decided and set on a machine,the next question was , in or out.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
voltage doubler efficiency
