# transformer

Hi,
A transformer is rated 20kva 3300/200V. To circulate rated current in the primary, what is the value of the voltage to be applied and how to arrive at it?
My doubt is in Short circuit test, we apply a voltage less than the rated on primary to get rated primary current. But rated primary current is calculated by 20kva/3300).. I am terribly confused. Somebody please hel me..

 tkrussell Posts: 9,673, Reputation: 3698 Senior Electrical & Lighting Expert #2 Jun 6, 2012, 10:28 AM

This may help:

http://nptel.iitm.ac.in/courses/IIT-...I/pdfs/1_7.pdf

http://theego.com/HND/UEE.PDF

http://www.ee.iitb.ac.in/~drivelab/E...E003_EXPT2.pdf
 nik1989 Posts: 3, Reputation: 1 New Member #3 Jun 6, 2012, 08:30 PM
Thank you sir but still I am not satisfied..

Quote:
 Originally Posted by tkrussell
 tkrussell Posts: 9,673, Reputation: 3698 Senior Electrical & Lighting Expert #4 Jun 7, 2012, 06:26 AM

Then try this:

Introduction to the Design and Analysis of Building Electrical Systems - John H. Matthews - Google Books

Why are you asking this question?
 nik1989 Posts: 3, Reputation: 1 New Member #5 Jun 7, 2012, 06:49 AM
Sir my doubt is: Rated current is the ratio of rated output(say 20kvA) and rated Voltage(say 3300V) in a 20kva 3300/220V transformer. In short circuit test we short LV winding and apply reduced voltage to the primary so as to circulate rated current in the primary. How does rated current flow when a reduced voltage is applied? I am not able to understand that.
Thank you..
 tkrussell Posts: 9,673, Reputation: 3698 Senior Electrical & Lighting Expert #6 Jun 7, 2012, 07:21 AM

Simply by the virtue of a short circuit allows and causes the rated current to flow in the sec winding with low voltage applied to the pri.

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