Читать книгу Arc Flash Hazard Analysis and Mitigation - J. C. Das - Страница 46

1 The calculated symmetrical three-phase bolted fault in a 480-V switchgear assembly is 40 kA. Using IEEE equations, calculate the arc fault current. Assuming that the fault is cleared in 0.1 seconds, both for Ia and 85% Ia, calculate the incident energy release and arc flash boundary. Use the gap length and working distance as per IEEE tables. The 480 V three-phase system is high resistance grounded.

2 Repeat with Lee’s equations.

3 Repeat using Equation (1.9) of the text.

4 Consult NFPA 70 E and the text in this paper and specify the PPE outfits for category 3 and 4 hazard levels in detail.

5 What is the IEEE intent of calculating a second arcing fault current at 85% of Ia?

6 List five points in order of their importance for worker’s safety.