# problem with this calculation see if i am right. or they posted it wrong

1. Junior Member
Join Date
May 2016
Posts
3
Reputation

## problem with this calculation see if i am right. or they posted it wrong

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.

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.

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

4. Junior Member
Join Date
May 2016
Posts
3
Reputation
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

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