Services, Grounding & Bonding第 44 / 120 题
What is the secondary full-load current of a 75 kVA transformer with a 208Y/120-volt, three-phase secondary?
a.120 amperes
b.361 amperes
c.208 amperes
d.104 amperes
解析
Secondary current is I = VA / (1.732 x E) = 75,000 / (1.732 x 208) = 75,000 / 360.3, or about 208 amperes. The 361-ampere answer divides by the voltage alone, 120 amperes uses the phase voltage incorrectly, and 104 amperes is roughly half the correct value.
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