E Rating
E Rating
(OP)
Does anyone know the origin of the "E" in E Rating? I know Edison invented the first safety fuse, but I don't think the E was established from his name. I don't have the NEMA spec to see if they specify.
Thanks,
SK
Thanks,
SK






RE: E Rating
This is one of several classes. Others are R, K, T and C. These are defined in ANSI C37.42. I'm not sure the "E" is significant of anything other than the time-current characteristics of the fuse.
RE: E Rating
SK
RE: E Rating
Class E is designed primarily for transformer protection, R is for motors, K and T are mostly used for distribution cutouts, K being relatively faster than T. There is also a class H that is used where high surge currents are encountered.
RE: E Rating
RE: E Rating
But the E class alone does not designate the TC characteristic. S&C Power fuses, all with the E rating, can be obtained in standard, slow, and very slow flavors.
RE: E Rating
RE: E Rating
For ratings <=100A, melt in 300s for current between 200% and 240% of rating
For ratings >100A, melt in 600s for current between 220% and 260% of rating
RE: E Rating
RE: E Rating