Transformers Level II Lesson 5: Transformer Overcurrent Protection with Associated Tap Rules (17 Questions; 3rd Year)

Transformers Level II Lesson 5:
Transformer Overcurrent Protection with
Associated Tap Rules (17 Questions; 3rd
Year)


Question b1: bIn bgeneral, btransformer bsecondary bconductors bare bnot bconsidered bto
bbe bprotected bby bthe bprimary bovercurrent bprotective bdevice. b- bcorrect
banswers✔✔True, b240.4(F)


Question b2: bAn binstallation bconsists bof ba b10-kVA, bsingle-phase btransformer bwith ba
b440-volt bprimary band ba b110-volt, b2-wire bsecondary busing bTHWN bcopper
bconductors. bNo bsecondary bOCPD bis binstalled. bThe bsecondary bloads bare
bconsidered bto bbe bnoncontinuous bloads. bCalculate bthe bminimum bsize bsecondary
bconductors brequired bto bhandle bthe bsecondary bfull-load bcurrent bfor bthis
btransformer. b(Assume bterminations bare brated bfor b75°C.) b- bcorrect banswers✔✔3
bAWG


Question b3 b(2 bQuestions) b- bcorrect banswers✔✔30 bA bmax. bprimary bOCPD

25 bA bmax. bprimary bOCPD

Question b4 b(3 bQuestions) b- bcorrect banswers✔✔6 bAWG b
35 bA
25 bA

Question b5 b(2 bQuestions) b- bcorrect banswers✔✔70 bA bmax. bprimary bOCPD

50 bA bmax. bprimary bOCPD

Question b6: bWhat bis bthe bminimum bsize bTHWN bsecondary bconductors brequired bfor
bcompliance bwith b240.21(C)(2)(1)? b- bcorrect banswers✔✔3 bAWG bTHWN


Question b7: bWhat bis bthe bminimum bsize bTHWN bsecondary bconductors brequired bfor
bcompliance bwith b240.21(C)(2)(4) band b240.21(C)(2)(1)? b- bcorrect banswers✔✔3
bAWG bTHWN