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Hameedullah Ekhlas
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Join Date: Feb 2010
Posts: 187
Good Answers: 11

tri-rating Transformer

12/02/2010 7:52 AM

Greeting all,

Does anyone have some information regarding to tri-rating (25/30/36 MVA) transformer. I searched google too but could not find such a satisfactory answer. I could not understand the transformer's real size.

Thanks.
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Anonymous Poster
#1

Re: tri-rating Transformer

12/02/2010 8:14 AM

There are basically two types of tri-rating.

1. FOFA rating(forced oil forced air)

25MVA with only convection cooling. no oil pumps , no forced air cooling.

30MVA with oil pumps are working for circulating oil for cooling.

36MVA with both oil pump and fans are working.

2. Normal,contingency and emergency rating.

25 MVA load at 55 deg c.

30 MVA load as 60 deg rise for six hours.

36 MVA load as 65 deg rise for 4 hours.

The transformers without oil pump and fans with the tri-rating has to be undertand that it can be upgraded as 25/30/36 MVA.
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Hameedullah Ekhlas
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Join Date: Feb 2010
Posts: 187
Good Answers: 11
#2
In reply to #1

Re: tri-rating Transformer

12/02/2010 8:23 AM

thanks guest.
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PeterT
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Join Date: May 2010
Location: Liverpool, NY
Posts: 961
Good Answers: 131
#5
In reply to #2

Re: tri-rating Transformer

12/03/2010 3:17 PM

It can also be accomplished with an ONAF transformer, with two stages of fans (no oil pumps). First rating is natural (air) cooling, second is first stage of fans operating, second is with both stages of fans.

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JRaef
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United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
Posts: 4665
Good Answers: 804
#3

Re: tri-rating Transformer

12/02/2010 8:48 AM

GA for "Guest", too bad he/she did not register.

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 ** All I every really wanted to be, was... A LUMBERJACK!.**
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Anonymous Poster
#4
In reply to #3

Re: tri-rating Transformer

12/02/2010 9:56 AM

He deserves the great answer.
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Anonymous Poster
#6
In reply to #3

Re: tri-rating Transformer

12/05/2010 8:18 AM

Actually the "'Guest" is very lowly and doesn't a glory from any one.
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