Page 48 - Application Guide Semiconductor Fuse Link

Appendix

Semiconductor device

I
FSM peak half-cycle surge withstand current of semiconductor A
device
I0 r.m.s. surge withstand current (= IFSM / 2 ) A
t0 duration of half-cycle s
N
N exponent in device withstand formula I t = constant

Line-commutated converters

F1 denotes fuse in series with device to be protected
F2 denotes fuse in line input to converter (F1 or F2 fuses are
used, but not both)
F3 denotes fuse on d.c. side
Ed0 maximum d.c. output of line-commutated converter V

A ,
B ,
C instantaneous a.c. source voltages V
n number of parallel paths (legs) in high-power converter
ILEG r.m.s. current per leg A
IF r.m.s. fault current A
2
2
P prearcing (melting) I t A s
2
2
T total clearing I t A s
a.c. voltage rating factor for regenerative converter
KAC
KDC d.c. voltage rating factor for regenerative converter
Forced-commutated inverters

R2 ,L2 leg resistance & inductance , H
supply fi lter resistance & inductance , H
RF , LF
C reservoir capacitance F
EM maximum permissible capacitor voltage V
maximum permissible capacitor voltage at start of arcing V
UPM

48