Question 13108 of 844 · Washington 01 Journey Level Electrician Exam
A 15 kVA, single-phase transformer with a 240 volt primary is protected on the primary side only. Which statement about its primary current is correct?
Exactly one answer is correct.
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Correct answer to question 13108
- D: It is 62.5 A, so the 125 % primary rule applies
Explanation
Primary current is 15,000 / 240 = 62.5 A. Because that is 9 A or more, primary-only protection uses 125 %; the 167 % and 300 % limits apply only to primary currents below 9 A and below 2 A.
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