ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Thought this was funny
by Ronny - 12/03/20 06:08 PM
From an outsider- How does tipping work?
by gfretwell - 12/02/20 02:38 PM
Happy Thanksgiving
by Trumpy - 12/02/20 04:11 AM
Where is Everyone?
by Trumpy - 12/02/20 03:51 AM
What does your work place look like?
by Trumpy - 12/02/20 03:42 AM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 16 guests, and 17 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
dry type transformer failure #205512 02/28/12 10:36 AM
Joined: Feb 2012
Posts: 1
D
Danny00915 Offline OP
New Member
I have a 50kVA dry type transformer which had failed, with rating:

1. Input (LV, primary winding): 400V, 72.17A
2. Output (HV, secondary winding): 21.5kV, 1.34A

The failed area was found to be the HV winding, where short circuit of winding and sign of local overheating was observed . Calculations showed no overload to input or output.

What would have cause the overheating? probable cause of the failure?

Work Gear for Electricians and the Trades
Re: dry type transformer failure [Re: Danny00915] #205526 02/29/12 03:18 PM
Joined: Dec 2002
Posts: 204
G
geoff in UK Offline
Member
Simple transformer insulation failure? It only takes one turn to short out and rapid overheating follows causing progressively more insulation failure.
Possible causes? Weak insulation since manufacture, moisture ingress, vibration, transient voltage surge, hotter than designed operating environment, - I'm sure there are more I can't just think of.

Re: dry type transformer failure [Re: Danny00915] #205527 02/29/12 05:30 PM
Joined: Jul 2004
Posts: 9,547
G
gfretwell Offline
Member
Is it getting plenty of air? These things, in confined space, can heat up quickly.


Greg Fretwell
Re: dry type transformer failure [Re: Danny00915] #205528 02/29/12 10:22 PM
Joined: Apr 2002
Posts: 7,218
HotLine1 Offline
Member
100% agree with that Greg> I remember a plant where some employees used a 75KVA for a lunch warmer with help from some cardboard & welding screen curtains! A situation that could have become a njghtmare.


John
Re: dry type transformer failure [Re: Danny00915] #205555 03/03/12 05:31 PM
Joined: Feb 2004
Posts: 1,436
Lostazhell Offline
Member
We had an old Westinghouse padmount 12kv pri 480V sec 1000kva that inadvertently was loaded up with >1600 hp in oil pumping units & steam genset pumps & blowers.. It ran this way for quite some time & wasn't discovered until we ran into some low voltage issues in a control room... The load was divided up with 2 banks of 167s added. The padmount still runs part of the field..


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Joe Tedesco
Joe Tedesco
Boston, Massachusetts USA
Posts: 2,749
Joined: October 2000
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 20
Popular Topics(Views)
272,213 Are you busy
206,102 Re: Forum
194,100 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3