The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 9 replies
  • Subscribers 31 subscribers
  • Views 1786 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Load Calculations for 400v single phase floodlighting

seansasta
Hi Folks

Could someone please advise if my calculations below are correct? I'm calculating total load on a 3 phase 400v system for a floodlighting load consisting of 36 No 400v single phase ("2-phase") Luminaires. I thought my calc's were correct then I read some other posts online which used 3 phase formula (as if the stated lighting load was 3 phase) which left me with enough doubt in my calc's to seek some expert advice from you guys...

Supply: 3ph/400V

Load: 36No Philips OPTIVISION MVP507 1xMHN-LA2000W/400V/842 WB/60, with a stated load of 2123 W each, equally divided across the 3 phases, (I have assumed a Pf of 0.9 for the ballasts).

I have treated these as single phase loads, therefore...

I total = (2123*36)/(400*0.9) = 212.3A; divided equally across 3 phases = 71 A (70.77) line current

Therefore, (Assuming I used the correct calculations above) total 3 phase power in KW = ((400*1.732*0.9*71)/1000) = 44.27 KW


Any confirmations or corrections would be greatly appreciated.


Thanks

Parents
  • 0
    Hi Broadgage


    Thanks for your response, believe it or not but your calc's below are exactly where I started out on my first assessment, total all of the 2 phase loads then treat the sum as one 3 phase load then divide back by number of fittings per phase to get the current draw for each fitting; using the power factor allowances in calc's below give us 125/12 = 10.4A per luminaire (and maybe my issue was overthinking the problem), but, apart from less volt drop, I couldn't see the advantage in the common use of 400v luminaires for stadium lighting as the current draw on a 230v luminaire with the same power rating (assuming the same Pf) would be almost identical...(2123/(230*0.9))=10.25A. This is what got me thinking the power rating for the 400v luminaires should be treated as single phase to calculate the current, then work back from the line current to calculate the total 3-phase power....I stand corrected! Thanks for your help. I'd be interested in your thoughts on pro's/cons of 400v versus 230v luminaires in this scenario, I always thought there would be a reduced current draw with the higher voltage fittings?
Reply
  • 0
    Hi Broadgage


    Thanks for your response, believe it or not but your calc's below are exactly where I started out on my first assessment, total all of the 2 phase loads then treat the sum as one 3 phase load then divide back by number of fittings per phase to get the current draw for each fitting; using the power factor allowances in calc's below give us 125/12 = 10.4A per luminaire (and maybe my issue was overthinking the problem), but, apart from less volt drop, I couldn't see the advantage in the common use of 400v luminaires for stadium lighting as the current draw on a 230v luminaire with the same power rating (assuming the same Pf) would be almost identical...(2123/(230*0.9))=10.25A. This is what got me thinking the power rating for the 400v luminaires should be treated as single phase to calculate the current, then work back from the line current to calculate the total 3-phase power....I stand corrected! Thanks for your help. I'd be interested in your thoughts on pro's/cons of 400v versus 230v luminaires in this scenario, I always thought there would be a reduced current draw with the higher voltage fittings?
Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines