Previous in Forum: Reducing a 0-5v wire to output only 0-1.3v...help please   Next in Forum: Convert 500V DC to 220V AC
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
6 comments
Rate Comments: Nested
tauqeer
Active Contributor

Join Date: Jan 2008
Posts: 11

VA & power

01/21/2008 10:42 PM

what is the difference between VA and power
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
frankcorners
Associate

Join Date: Jan 2008
Location: Bangalore , India
Posts: 52
#1

Re: VA & power

01/21/2008 11:13 PM

power also equates the powerfactor ..... thats VxIxCOSØ

va has only VxI

__________________
 Frank - Catch my statement if you can.
Register to Reply
nesubra
Guru

Join Date: Nov 2006
Posts: 729
Good Answers: 2
#6
In reply to #1

Re: VA & power

01/26/2008 4:30 AM

VA is power In DC.In AC it is just Volt ampere.(Normally in kilo Volt Ampere)To convert it into power you need to multiply that by power factor.

__________________
 To avoid crticism do nothing,say nothing,be nothing
Register to Reply
2
Anonymous Poster
#2

Re: VA & power

01/22/2008 12:29 AM
Power, in Watts, is simple. An incandescent light bulb, 60 Watts say, uses 60 Watts of power. In this case VA and Power are the same thing. But for example in lighting requiring a ballast the two are different. Two things can make VA different from the Power. First is capacitive reactance, coming from a capacitor. The second is inductive reactance, this occurs when a conductor is wrapped in a coil such as in a ballast. A 400W Metal Halide light bulb uses 400 Watts but its VA will likely be around 485VA because of its ballast which contains a coil and thus reactance. Mathematically VA, Power and Reactive Power make up a right triangle. VA being the hypotenuse. VA is the result of vectorially adding the power and reactive power. Thus a 400W incandescent bulb ar 240V will draw just over 1.5 A (400VA/240V)whereas a 400W Metal Halide at 240V with ballast will draw closer to 2 A(485VA/240V). Power companies read Watts in charging the consumer. In households the Watts is usually close to VA but in larger industrial complexes with lots of reactive loads (motors, etc.) the VA will be much higher than the Watts (poor power factor) and this means line current will be greater than what they are charging for in Watts and thus putting a greater strain on the power companies infrastructure. Therefore they will penalize poor power factor installations.
Register to Reply Good Answer (Score 2)
No more Good Answers.
Anonymous Poster
#3

Re: VA & power

01/22/2008 4:26 AM

copper losses are in current, & iron losses are in voltage , so when ever losses are combined they are known as VI
Register to Reply
Anonymous Poster
#4

Re: VA & power

01/22/2008 5:07 AM

http://en.wikipedia.org/wiki/Power_factor
Register to Reply
ethobil
Power-User
Nigeria - Member - Member

Join Date: Aug 2007
Location: Port Harcourt Nigeria
Posts: 206
Good Answers: 3
#5

Re: VA & power

01/23/2008 3:25 AM

In simple terms, leaving out the mathematics of power triangle;

VA is the rated power while power is the actual power out put in a given system.

Cheers,

Ethobil

__________________
 Join us to make the world a better place: Propergate peace.
Register to Reply
Register to Reply
Have a Different Question?
6 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (3); ethobil (1); frankcorners (1); nesubra (1)

Previous in Forum: Reducing a 0-5v wire to output only 0-1.3v...help please   Next in Forum: Convert 500V DC to 220V AC

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (64 right now)
Show Members
Advertisement