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# Determine the approximate short circuit current available

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1.  Junior Member
Join Date
May 2016
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7
Reputation ## Determine the approximate short circuit current available

Using the given information, determine the approximate short circuit current available at the transformer secondary: 13,800-277Y/480V, 2500 kVA, 5% Impedance

60,000 A
54,500 A
42,000 A
37,500 A
25,000 A

first should be 480Y/277 not 277y/480.

basically this would be the calculation. I= (2500*1000)/(480*1.732)= 3007.08
z= (100/5)= 20
short circuit = 3007.08*20= 60189

so i would just go with the closest answer correct? and also they should fix the error on 277Y.  Reply With Quote

2.  Junior Member
Join Date
Jan 2015
Location
Minnesota
Posts
2
Reputation ## Agreed

I work it out to the same answer. Seems you did it right and I would go for the closest answer. Originally Posted by rasilva Using the given information, determine the approximate short circuit current available at the transformer secondary: 13,800-277Y/480V, 2500 kVA, 5% Impedance

60,000 A
54,500 A
42,000 A
37,500 A
25,000 A

first should be 480Y/277 not 277y/480.

basically this would be the calculation. I= (2500*1000)/(480*1.732)= 3007.08
z= (100/5)= 20
short circuit = 3007.08*20= 60189

so i would just go with the closest answer correct? and also they should fix the error on 277Y.  Reply With Quote

3. The questions clearly states "determine the approximate short circuit current". Go with the closest answer.  Reply With Quote

4.  Junior Member
Join Date
May 2016
Posts
7
Reputation  Originally Posted by madMAX The questions clearly states "determine the approximate short circuit current". Go with the closest answer.

yes sir but its wrong wording that what confused 277y/480 doesn't exist, 480y/277 exist  Reply With Quote

5.  Junior Member
Join Date
Apr 2017
Posts
1
Reputation ## fault current Originally Posted by rasilva Using the given information, determine the approximate short circuit current available at the transformer secondary: 13,800-277Y/480V, 2500 kVA, 5% Impedance

60,000 A
54,500 A
42,000 A
37,500 A
25,000 A

first should be 480Y/277 not 277y/480.

basically this would be the calculation. I= (2500*1000)/(480*1.732)= 3007.08
z= (100/5)= 20
short circuit = 3007.08*20= 60189

so i would just go with the closest answer correct? and also they should fix the error on 277Y.
2500 x 100
1.732 x .480 x5

250,000/4.1568= 60,142  Reply With Quote

6. ## Explain the math

Could someone explain the math a little more in depth? Never mind I was confused in Z, but looking over it again I understand.

Last edited by Ronwilson1801; December 29, 2018 at 09:27 AM.  Reply With Quote

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