transformers

[sleepy]

code section 450.21 (b) transformer larger than 112.5 with class 155
is class 155 the standard for transformer
can i get any info on this
where it sayes 150kva transformer shall be installed in a room with fire resistant
construction but than in exceptions it sayes transformer with class 155 or higher
it just has to be 6 feet away from materials
class 155 is that temperature rise
any help
thanks

 

[russ]

Transformer class

Transformer class

Transformer Insulation Temperature Class



Winding type - Temp Rise (Max)



Class 105(A) -75
Class 120(E) -90
Class 130(B) -95
Class 155(F) -115
Class 180(H) -140
Class 200 --160
Class 220 --180
Class 250 --210