Selection standard of high voltage cabinet copper bar

Selection standard of high voltage cabinet copper bar

Selection criteria for high-voltage cabinet copper bars Center cabinet KYN28 PT cabinet

Formula in GB3906 [Appendix D]: S=I/a√(t△θ)

In the formula: I-rated short-time withstand current; a-material coefficient, copper is 13, and aluminum is 8.5; t-rated short-circuit duration; Δθ-temperature rise (K), generally 180K for bare conductors, For 4S duration take 215K.

then:

The minimum cross-sectional area of the copper busbar of 25KA/4S system S=(25000/13)*√4/215=260 mm2 60*5 is enough.

31.5KA/4S system copper busbar minimum cross-sectional area S=(31500/13)*√4/215=330 mm2

40KA/4S system copper busbar minimum cross-sectional area S=(40000/13)*√4/215=420 mm2

63KA/4S system copper busbar minimum cross-sectional area S=(63000/13)*√4/215=660 mm2

80KA/4S system copper busbar minimum cross-sectional area S=(80000/13)*√4/215=840 mm2

The ground bus is considered according to 86.7% of the rated short-time withstand current of the system:

25KA/4S system grounding copper busbar minimum cross-sectional area S=260*86.7%=225mm2

31.5KA/4S system grounding copper busbar minimum cross-sectional area S=330*86.7%=287mm2

40KA/4S system grounding copper busbar minimum cross-sectional area S=420*86.7%=370mm2

63KA/4S system grounding copper busbar minimum cross-sectional area S=660*86.7%=580mm2

80KA/4S system grounding copper busbar minimum cross-sectional area S=840*86.7%=730mm2