10.9交叉互联系统的例行试验中电缆外护套、绝缘接头外护套、绝缘夹板对地直流耐压试验施加电压( ),加压时间( )
A.5kV,30s
B.5kV,60s
C.10kV,30s
D.10kV,60s
正确答案是B