Separation of Transformers for Class 1E Systems in Nuclear Power Plants

Table 2

The result of short circuit current analysis for APR1400.

Power source	4.16 kV bus	Cat. I	Cat. II	Cat. III	Cat. IV	Cat. V
UAT	Non-Class 1E	39.1 kA	43.5 kA	42.4 kA	42.4 kA	43.5 kA
	Bus A
	Non-Class 1E	38.2 kA	35.1 kA	37.4 kA	36.0 kA	42.0 kA
	Bus B
	Class 1E	35.1 kA	32.2 kA	34.7 kA	33.3 kA	43.0 kA
	Bus A
	Class 1E	36.7 kA	33.5 kA	35.7 kA	34.3 kA	43.0 kA
	Bus B
	Non-Class 1E	—	42.7 kA	42.4 kA	42.4 kA	42.6 kA
	Bus A
	Non-Class 1E	—	35.4 kA	37.9 kA	37.4 kA	42.7 kA
	Bus B
	Class 1E	—	32.5 kA	36.2 kA	34.7 kA	43.0 kA
	Bus A
	Class 1E	—	33.8 kA	35.0 kA	35.7 kA	43.0 kA
	Bus B

the plant start-up condition (Cat. I), the electric power system receives power only through UAT.