4.8 kV System

[bfdeleen]

I have encountered the 4.8 kV, 60 Hz system for the first time and I cannot see an overall advantage to it compared to a 4.16 kV system. Circuit breakers come in maximum voltages of 4.76 and 8.25 kV, so the later is needed. Since there is a 4.8 kV generator, it is not inconceivable that it could operate slightly higher sometime. It begins to look like switchgear and wiring must be at 8.25 kV, even though the nominal system voltage is below 5 kV. Does anyone have previous experience with this voltage?

 

[busbar]

Minor aside: ANSI C84.1-1995 […Voltage Ratings, 60 Hertz] lists 4800V as one of a number of standard ratings for 3-wire medium-voltage service, but not as a ‘preferred’ voltage.

It is listed in the category of, “…in substantial use in existing systems,” with the comment, “Economic considerations will require that these voltages continue in use and in some cases may require that their use be extended; however, these voltages generally should not be utilized in new systems or in new voltage levels in existing systems.”

Oddly, acceptable voltage limits are: 5080 [>5kV] — 4160 [a preferred nominal voltage itself.]