ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
220/230/240V 60Hz Systems
by gfretwell. 09/16/18 12:37 PM
Acronis Backup 2017
by gfretwell. 09/16/18 12:46 AM
Inspection camera help
by Bill Addiss. 09/15/18 11:32 AM
Tingle off the water spigot
by Trumpy. 09/15/18 03:24 AM
Lighting Load questions
by HotLine1. 09/14/18 07:04 PM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
1 registered members (cableguy619), 35 guests, and 22 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
3 phase voltage drop calculations #8727
04/02/02 12:58 AM
04/02/02 12:58 AM
S
sparkyga  Offline OP
Member
Joined: Apr 2002
Posts: 15
V.K.
Hi

My name is Greg and I work over in Bosnia on a Canadian S.F.O.R. base for a company out of Calgary.As much as I try to do my best to keep to the C.E.C. when doing work, it is not always possible to do, due to supplies or manpower. I found this site yesterday and look forward to using it often for keeping up with my code and hopefully for some help when I get stuck. I have a formula out of the N.E.C. for 3 phase voltage drops that talks about a Q factor for cables above 2/0 .1)What is the Q and how do i use it ?
2) Is there a better calculation I can use for 3 phase calculations? Many of our runs are very long, and alot of our services are large so I like to be right before I purchase cables
Thank you for your time and look forward to hearing some results
Greg Smith
Camp Black Bear
V.K.
Bosnia

Work Gear for Electricians and the Trades
Re: 3 phase voltage drop calculations #8728
04/02/02 08:03 AM
04/02/02 08:03 AM
R
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Do you mean "K"?

Re: 3 phase voltage drop calculations #8729
04/02/02 11:30 AM
04/02/02 11:30 AM
T
The Watt Doctor  Offline
Member
Joined: Dec 2001
Posts: 435
Mont Belvieu, TX
Hey Greg,
Greg here. Just remember that VD is equal to (2) "licks" over a "Cool Mama". Now this applies to your personal life as well as electric work.
Notice:
VD=(2LIK)/Acm
The above formula is for single phase applications.
For three phase applications use the following:
VD=(2LIK.866)/Acm
VD=Voltage Drop (or it could be you know, V.D.) [Linked Image]
L=length of circuit from source to load (one direction only, thus the "2" in the formula)
I=current in amperes
K=constant for either copper or aluminum
Acm=Area of conductor in circular mils (or it could be "A cool Mama") [Linked Image]
The .866 is thrown into the formula for 3 phase applications, and is equal to the square root of 3 divided by 2.
The constants for copper and aluminum may vary depending on who you ask, but I was taught that Copper is 10.4, and Aluminum is 17.1.
If you want to avoid "VD" in your personal life, stay away from those "Cool Mamas", but if you want to avoid "VD" in your electrical work use the above formulas, and I'm sure that you will be O.K.
Always, always remember, "Proper electric today, keeps The Watt Doctor away."
And by the way, The Watt Doctor only does check ups on one kind of VD, and it has to do with the kind where electrons, conductors, difference of potential, etc are involved, not the other.

Best Voltage Dropological Regards,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX
Re: 3 phase voltage drop calculations #8730
04/02/02 11:59 AM
04/02/02 11:59 AM
E
eman1963  Offline
Member
Joined: Jan 2002
Posts: 22
rhode island
Nice answer doc. lol

Re: 3 phase voltage drop calculations #8731
04/03/02 09:34 PM
04/03/02 09:34 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,024
Brick, NJ USA
SparkyGA:
You may want to see if you can locate a great little calculator called "ELECTRICALC"
Matter of fact an ad just popped up to the left of this page. I think it's in the $100 range, but I think it' is well worth it.

Does a whole lot....check it out
John


John
Re: 3 phase voltage drop calculations #8732
04/03/02 10:25 PM
04/03/02 10:25 PM
R
Ron  Offline
Member
Joined: Mar 2002
Posts: 582
White Plains, NY
Check toward the bottom of the web page below for volt drop calcs in feet or meters. http://www.mikeholt.com/free/free.htm


Ron
Re: 3 phase voltage drop calculations #8733
04/04/02 09:22 PM
04/04/02 09:22 PM
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
"Q" [Figure Of Merit most of the time] can either be applied to the VD formula as Skin Effect Ratio / Calc, or used in conjunction with Reactances [Xl &/or Xc] to determine an Impedance.

It's in one of my EE books some place [Linked Image]

"K" is typically for "Constant", as indicated by Doc, and is Conductor dependent.

Are you planning to calc a Voltage Drop using the "Complete AC" method - which applies the Power Factor, Total Conductor Impedance [Resistance and Reactance(s)], Conductor Type [Skin Effect] and Magnetic / Non-Magnetic raceway?

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
sparky66wv
sparky66wv
West Virginia
Posts: 2,236
Joined: November 2000
Show All Member Profiles 
Top Posters(30 Days)
Admin 13
Trumpy 11
sparky 9
Popular Topics(Views)
249,290 Are you busy
187,227 Re: Forum
176,587 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.027s Queries: 14 (0.004s) Memory: 0.9869 MB (Peak: 1.1355 MB) Zlib enabled. Server Time: 2018-09-20 00:36:56 UTC