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Anonymous Poster #1

Scope of Work for Inspection Main Transformer

11/15/2011 2:32 AM

Dear All

we have main transformer with capacity 27 MVA. The transformer is used to deliver electricity with a capacity of 20 MVA. Due to high enough temperature transformer that is 79 degree C, especially in the afternoon with the exhaust temperature of 489 degrees C, then the load of generator could not be maximum. Maximum load is only 15 MW. Due to implementation of Combustion Inspection for the next month, then what is the scope of work that should we do to the temperature transformer can be derive, so that the load can be increased at least 2MW.?
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PWSlack
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#1

Re: scope of work for inspection main transformer

11/15/2011 4:42 AM

What does the transformer manufacturer say on this topic?

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rita.triani
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#5
In reply to #1

Re: scope of work for inspection main transformer

11/16/2011 2:16 PM

the manufacture is alstom. the specification data that we can read is,

manufacture : alstom,

rating : 27 MVA

Primary volt : 11 kV

Secondary Volt : 154 kV

vektor group : Yd11

Frequency : 50 Hz

Xt : 11%

thanks
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TonyS
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#2

Re: Scope of Work for Inspection Main Transformer

11/15/2011 9:32 AM

What's the generator exhaust temperature to do with the transformer?

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SolarEagle
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#3

Re: Scope of Work for Inspection Main Transformer

11/15/2011 11:36 AM

You might consider a cooling upgrade...ie. increasing number of fans...

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wareagle
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#4

Re: Scope of Work for Inspection Main Transformer

11/15/2011 2:25 PM

Quote "we have main transformer with capacity 27 MVA. The transformer is used to deliver electricity with a capacity of 20 MVA. Due to high enough temperature transformer that is 79 degree C, especially in the afternoon"

Are you saying that you are operating the transformer at 79C? What is the name plate rating? You normally find the transformer with 2 ratings. An example might be 20 mva 55C/65C. This transformer with fans is rated 20 mva at 55C and 22.5 mva at 65C. Do you have fans on the transformer? Are you in the summer season at your location?
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rita.triani
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#6

Re: Scope of Work for Inspection Main Transformer

11/16/2011 2:22 PM

after doing DGA test to the transformer, we get some data as,:

Hydrogen (H2) 400 ppm

water (H20) 104 ppm

Carbon dioxide (CO2) 17987 ppm

Carbon Monoxide (CO) 536 ppm

Ethylene (C2H4) 68 ppm

Ethane (C2H6) 195 ppm

methane (CH6) 137 ppm

acetylene (C2H2) <0.5 ppm

TDCG 1335 ppm

because of the data above, need your recommendation as soon as.

regards
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wareagle
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#7
In reply to #6

Re: Scope of Work for Inspection Main Transformer

11/16/2011 5:28 PM

Quote " because of the data above, need your recommendation as soon as."

Then why not answer the question?

Are you saying that you are operating the transformer at 79C? What is the name plate rating? You normally find the transformer with 2 ratings. An example might be 20 mva 55C/65C. This transformer with fans is rated 20 mva at 55C and 22.5 mva at 65C. Do you have fans on the transformer? Are you in the summer season at your location?

Does it have a voltage regulator? capacity? Or is it on a network?

IF you can not find the rating, suggest you ask the mfg for assistance.
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SolarEagle
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#8
In reply to #6

Re: Scope of Work for Inspection Main Transformer

11/17/2011 11:41 AM

You've got too much moisture, should be below 35ppm, you have to dry it out...You're CO2 readings are off the chart, probably due to cellulose insulation degradation, due to moisture...otherwise looks to be in fair condition...from this limited data...

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rita.triani
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#9
In reply to #8

Re: Scope of Work for Inspection Main Transformer

11/18/2011 1:19 AM

thank solar eagle.. you are right, the data is very limited. we cannot do anything before the transformer is off. Right now the condition of transformer is still running with high temperature about 70-78 C. Maximum Load is only 15 MW, from the capacity is 20 MW.
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PWSlack (1); rita.triani (3); SolarEagle (2); TonyS (1); wareagle (2)

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