ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
A client of mine has contracted the services of an engineering firm to perform an arc flash study for one of their projects. There is a work sheet the firm has asked that my client fill out, and one of the things they are asking for is the available fault current (AFC) from the three phase utility transformer. They are asking for both phase to ground and phase to phase numbers, and that puzzles me. The calculation I am familiar with for calculating AFC does not differentiate, although it specifies line to line voltage; does that mean that it is phase to phase AFC, and for line to neutral/ground AFC I should use phase to neutral/ground voltage? That would mean that the infinite bus phase to phase AFC would be larger than the phase to neutral/ground AFC by a factor of sqrt3.