How to Find KVA

11 comments

Rate

aishaamadumamariama Associate Join Date: Jul 2009 Posts: 33	How to Find KVA 02/07/2011 5:38 AM
	how to calculate KVA, when the current per each phase is 200amp at 440volts for three phase circuit breaker or what size of generator is needed for such informations above I try to work it at.............v x I x pf [0.8 or 1.732] / 1000======457KVA v----Volt generated I-----Current or Amperage Pf----Power factor of load 440 x [200 x 3phase] x 1.732 /1000 457.248amp I am just confused, am I correct, or please help over this
	Register to Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

kvsridhar Guru Join Date: Sep 2009 Location: Temporarily at Ashburn, VA Posts: 2744 Good Answers: 164	#1 Re: Find KVA 02/07/2011 6:08 AM
	kVA = √3 * V I kW = √3 V * I * Cosφ = √3 * kVA __________________ Nothing worthwhile can ever be taught, it can only be learnt.
	Register to Reply Off Topic (Score 5)

JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#2 In reply to #1 Re: Find KVA 02/07/2011 6:13 AM
	So Cosφ = √3 ? __________________ "Love justice, you who rule the world" - Dante Alighieri
	Register to Reply Off Topic (Score 5)

kvsridhar Guru Join Date: Sep 2009 Location: Temporarily at Ashburn, VA Posts: 2744 Good Answers: 164	#4 In reply to #2 Re: Find KVA 02/07/2011 6:24 AM
	OOPS! never post when sleepy Sorry OP, kW = Cosφ*kVA __________________ Nothing worthwhile can ever be taught, it can only be learnt.
	Register to Reply

pieface_ie Active Contributor Join Date: Nov 2010 Location: Ireland Posts: 15	#3 Re: Find KVA 02/07/2011 6:14 AM
	You do not use the power factor in calculating KVA. When you use the power factor your calculating the KW.
	Register to Reply

pieface_ie Active Contributor Join Date: Nov 2010 Location: Ireland Posts: 15	#5 Re: Find KVA 02/07/2011 6:26 AM
	Cosφ = KW/KVA
	Register to Reply

TonyS Guru Join Date: Aug 2010 Location: Resting under the Major Oak Posts: 4347 Good Answers: 181	#6 Re: Find KVA 02/07/2011 6:54 AM
	A x V x √3 x 3 / 1000 = KVA KVA x Pf = KW __________________ The reports of my death are greatly exaggerated.
	Register to Reply

Aseer Commentator Join Date: Oct 2009 Location: Dubai,UAE Posts: 62 Good Answers: 2	#7 Re: Find KVA 02/07/2011 8:33 AM
	KILOWATT (kW) = VOLTS x AMPERES x POWER FACTOR x 1.73 1000 To Convert Between kW and kVA kW to kVA kW / .85 = SAME VALUE EXPRESSED IN kVA kVA TO kW kVA * .85 = SAME VALUE EXPRESSED IN kW.... __________________ There are no shortcuts on the road to a great experience.
	Register to Reply

PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#8 In reply to #7 Re: Find KVA 02/07/2011 12:49 PM
	Yes, OK. Do turn off Caps Lock next time, eh? __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
	Register to Reply Score 1 for Off Topic

pnaban Guru Join Date: Jun 2010 Location: srilanka Posts: 2725 Good Answers: 5	#9 Re: How to Find KVA 02/08/2011 12:44 AM
	For sizing genset,kVA is not enough.You should know the pf of load to find kW of engine. PF varies with current or load. During starting of large motor across the line pf will go down to even 0.3 due to 6times FLA drawn.Voltage/Frequency drop should be within limits at generator terminals as well as motor terminals. __________________ pnaban
	Register to Reply

ldtam1109 Participant Join Date: Feb 2011 Posts: 1	#10 Re: How to Find KVA 02/08/2011 10:41 AM
	if you use 440 x [200 x 3phase] x 1.732 /1000 457.248amp you only know kVA of Load, you don't know kVA of general
	Register to Reply

Carl Pugh Power-User Join Date: Jun 2009 Posts: 134 Good Answers: 11	#11 Re: How to Find KVA 02/08/2011 1:19 PM
	When using line to line voltage kVA=ExIx1.732/1000 440x200x1.732/1000=152.4 kVA
	Register to Reply

Copy to Clipboard

Aseer (1); Carl Pugh (1); JohnDG (1); kvsridhar (2); ldtam1109 (1); pieface_ie (2); pnaban (1); PWSlack (1); TonyS (1)

You might be interested in: KVA Meters, Current Sense Amplifiers, Current Transformers

	Got Something to Say?
	Ask a Question Start a Discussion

	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 (57 right now) Show Members