ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
sparky 5
Recent Posts
Permit Snafus...AHJs and Contractors Jump in
by sparky. 04/29/17 05:59 PM
201 volt equipment?
by bigpapa. 04/29/17 12:15 AM
Schneider LC1D09
by jraef. 04/28/17 11:05 PM
Electrode boilers question
by annemarie1. 04/27/17 01:40 PM
Why cables look like they do
by LongRunner. 04/26/17 09:36 AM
New in the Gallery:
SE cable question
Popular Topics(Views)
234,952 Are you busy
169,778 Re: Forum
162,994 Need opinion
Who's Online Now
0 registered members (), 66 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#270 - 01/05/01 06:51 PM Transformer inrush current  
Alan McNeil  Offline
Member
Joined: Jan 2001
Posts: 18
Buzzards Bay, MA U.S.A.
Can anyone tell me what the inrush current of a 480/208 75kva transformer would be if it was typically loaded on the secondary side at around 135 amps? I know it goes way high, but I need a ball park figure for argument sake. My boss wants to know why they keep popping the breaker when the transfer switch goes back to normal power. I need a ball park figure


Work Gear for Electricians and the Trades

#271 - 01/06/01 11:09 PM Re: Transformer inrush current  
Bennie R. Palmer  Offline
Member
Joined: Nov 2000
Posts: 72
Milwaukie, OR 97267 USA
Alan: I calculated the maximum inrush current for a 75 KVA transformer as 990 amps.
I do not know the duration. The secondary load is irrelevant for inrush calculations.
A circuit breaker with a time trip curve that will permit 990 amps, with a duration necessary to establish core flux, would be required for starting the transformer.



Member Spotlight
togol
togol
NW In. USA
Posts: 421
Joined: September 2005
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.009s Queries: 14 (0.002s) Memory: 0.7429 MB (Peak: 0.8597 MB) Zlib enabled. Server Time: 2017-04-29 23:26:54 UTC