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Anonymous Poster

Lighting Transformer

02/21/2011 10:31 PM

Why 100 kVA lighting transformer is used in the power substation, while the voltage ratio is 415/415V,delta-star winding scheme ?

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Guru
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#1

Re: Lighting Transformer

02/21/2011 10:37 PM

Maybe the lighting circuits are phase-to-neutral 240V, not available on the primary side?

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Guru
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#2

Re: Lighting Transformer

02/21/2011 10:57 PM

Because that's what the Engineer designed it to be. If you look at the Engineering prints you'll find his name there. Send him an inter office e-mail and ask him.

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#3

Re: Lighting Transformer

02/22/2011 1:39 AM

Generally in a power station the 415 V supply is three wire.There is no neutral. Lighting is generally connected between phase and neutral. Hence, as a neutral has to be created a lighting transformer is used.

Regards,

S. V. Iyer

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Guru
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#4

Re: Lighting Transformer

02/22/2011 7:52 AM

Dear Guest,

In the Sub-Station -in the Step-down Transformer there may not be NEUTRAL. For Single Phase Circuit, NEUTRAL IS REQUIRED hence a small Transformer is used.

DHAYANANDHAN.S., INDIA

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Anonymous Poster
#5
In reply to #4

Re: Lighting Transformer

02/22/2011 9:16 AM

There's an echo around here

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#6
In reply to #4

Re: Lighting Transformer

02/22/2011 11:12 PM

You are absolutely right. Another reason is to limit the fault level.

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Guru

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#7

Re: Lighting Transformer

02/22/2011 11:50 PM

What is the rated voltage of generator?. If not 415V,a step down transformer with secondary voltage of 415V and earthed neutral could be used.

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pnaban
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Anonymous Poster
#8

Re: Lighting Transformer

02/23/2011 2:38 AM

Lighting transformers are usually installed to ensure the lighting supply voltage remains at the optimum level necessary for increased life of the fittings and lamps, over voltage can reduce this considerably.

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Power-User

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#9

Re: Lighting Transformer

02/23/2011 7:06 AM

Delta/ Star (neutral grounded) is used in substation for for the following reasons:

For electrical isolation in case of occurence of fault from primary side of transformer( i.e main L.T. Bus feeding from main transformer)

High % impedance of lighting transformer to restrict fault current.

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Manindra
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#10

Re: Lighting Transformer

02/24/2011 5:35 AM

Generally lighting loads suffer from frequent short circuits. Hence to isolate the main system from these disturbances, a lighting transformer with a delta star scheme may be used.

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mscs
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#11

Re: Lighting Transformer

03/19/2011 5:00 AM

Dear All, In our plant we use a 415/433 V lighting trafo for lighting distribution through LDB. Usually it is provided with Off Circuit Tap Changer to adjust the voltage on the Load Side when ever the Incoming Voltage increase or decreases. Through the star side single power for single phase load can be derived.

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