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Anonymous Poster

Grid Source Reactance

09/30/2008 3:54 PM

Hello everyone

I am currently reading a text book on power systems and I am currently on the above topic. However I do not understand the following equation when they work out grid source reactance = 1 divided by the grid infeed MVA pu. I understand how the infeed MVA pu is attained but where does the 1 come from when calcualting the reactance?

Thanks in advance

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martin-electrical
Associate

Join Date: Jul 2007
Posts: 41
#1

Re: Grid Source Reactance

09/30/2008 10:51 PM

Inductive reactance xl =2PiX

Capacitive reactance1/2piC.............. all another form of ohms law
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Flux
Active Contributor

Join Date: Jul 2008
Location: Finland
Posts: 22
#2
In reply to #1

Re: Grid Source Reactance

10/01/2008 1:20 AM

You forgot frequency. xl=2*pi*f*X or xc=1/(2*pi*f*C)
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martin-electrical
Associate

Join Date: Jul 2007
Posts: 41
#5
In reply to #2

Re: Grid Source Reactance

10/01/2008 8:39 AM

oops used frequency tooo many times this week .....
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Anonymous Poster
#3

Re: Grid Source Reactance

10/01/2008 3:40 AM

thank you guys
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Flux
Active Contributor

Join Date: Jul 2008
Location: Finland
Posts: 22
#4

Re: Grid Source Reactance

10/01/2008 4:55 AM

The above equations doesn't really cover what you are asking...

Are you sure you haven't mixed up MVAsc and MVAbase. Because in short sircuit calculations you can calculate reactance to the fault by using equation X(pu)=1/MVAsc(pu) or X(pu)=MVAbase/MVAsc...
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Anonymous Poster
#6
In reply to #4

Re: Grid Source Reactance

10/01/2008 10:37 AM

Hi Flux

the way its written in the book is:

working to 70 MVA base

grid infeed MVA pu = 1500/70= 21.43 pu

grid source reactance = 1/21.43 = 0.047 pu

I just can't figure out where the 1 comes from
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Anonymous Poster (2); Flux (2); martin-electrical (2)

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