Electrician Red Seal · Question
A 480V to 120/208V, 3-phase, delta-wye transformer has a kVA rating of 45. What is the full-load current on the secondary side?
The formula for full-load current in a 3-phase system is I = kVA / (V_line × √3). For the secondary, I = 45,000 VA / (208 V × 1.732) = 45,000 / 360.25 = 124.9 A
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Question: A 480V to 120/208V, 3-phase, delta-wye transformer has a kVA rating of 45. What is the full-load current on the secondary side?
Answer options: ✅ 125 A
- 216 A
- 108 A
- 62 A
Correct answer: 125 A
Explanation: The formula for full-load current in a 3-phase system is I = kVA / (V_line × √3). For the secondary, I = 45,000 VA / (208 V × 1.732) = 45,000 / 360.25 = 124.9 A, which is approximately 125 A.
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