ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Norwegian power?
by dsk. 04/26/19 03:56 AM
20amp breakers
by gfretwell. 04/25/19 10:19 PM
"Esoteric" countries and their wiring practices?
by winston_1. 04/23/19 02:34 PM
Welded Copper Connections
by gfretwell. 04/19/19 04:46 PM
Israel
by annemarie1. 04/18/19 02:35 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 3 guests, and 16 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Volt-Amp Conversion - Please Help #6066
12/21/01 12:14 PM
12/21/01 12:14 PM
Admin  Offline
OP
Administrator
Member
Joined: Oct 2000
Posts: 3,545
NY, USA
Posted for Todd
Quote
I'm trying to size a UPS for a piece of our equipment. How do you do it in VoltAmps? No one can tell me a conversion for VoltAmps.
Thanks

- Todd

Work Gear for Electricians and the Trades
Re: Volt-Amp Conversion - Please Help #6067
12/21/01 01:44 PM
12/21/01 01:44 PM
T
Tom R  Offline
Junior Member
Joined: Dec 2001
Posts: 3
Todd:

VA is the mathematical number you come up with when you multiply the voltage at a piece of equipment by the current that is being drawn by the equipment.

We would need to know what your givens are and what you are trying to convert from. The relationship between Wattage and VA is a little complicated so if that is what you are trying to convert I think you will need to know the power factor of your facility.

I will try to provide a brief over simplistic view of how the power factor relates to power. If you search this site you may find a detailed discussion about the subject, barring that I am sure someone will come along with a better explanation shortly.

VA is "apparent power" the equipment is using. This is the same as the "true wattage" ONLY when the power factor is unity (current and voltage exactly in phase).

In most cases the power factor of the system is less than unity (phase shift occurs whenever you are feeding a reactive load) and since the current and voltage are out of phase the apparent power (VA) that must be supplied to the equipment will be greater than the actual wattage required so VA is used to size the supply components to compensate for the out of phase relationship of the voltage and current.

Let us know exactly what are your know facts and what you are trying to convert to VA. Tom R.


[This message has been edited by Tom R (edited 12-21-2001).]

Re: Volt-Amp Conversion - Please Help #6068
12/21/01 03:57 PM
12/21/01 03:57 PM
J
Joe Carpenter  Offline
Member
Joined: Dec 2001
Posts: 50
USA
I would also like to see any information anyone has on the subject on sizing UPS systems and also on what types you would recommend. When is a central system with dedicated circuits practical versus small individual stand alone units?
I don't want to lead this original post off course, I just thought maybe we could expand it

Thanks


Featured:

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

 

Member Spotlight
RH1
RH1
California
Posts: 22
Joined: August 2009
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
254,588 Are you busy
190,795 Re: Forum
180,539 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.021s Queries: 14 (0.004s) Memory: 0.9523 MB (Peak: 1.0761 MB) Zlib enabled. Server Time: 2019-04-26 12:13:42 UTC