Page 28 - Ferraz semiconductor DIN
P. 28
Semiconductor fuses
Semiconductor (AC) fuses
®
Protistor Square-body Fuses
PSC aR sizes 3x - 450V to 700 VAC
Curves set
Sizes 30 - 31 - 32 - 33
I t Multiplier coefficient
2
2
Mean curve indicating variation of total I t (I t ) and total
2
t
operating time T in accordance with working voltage U.
t
Example:
Fuse 350 A in size 30.
I = 10 000 A U = 500 V
p
At 660 V
2
2
I t = 80 000 A s T = 6 ms
t
t
At 500 V
I t = 80 000 x 0.72 = 57 600 A s
2
2
t
T = 6 x 0.72 = 4.3 ms
t
Dissipated power Arc voltage
Curve enabling calculation of dissipated Curve indicating peak arc voltage Um which
power P by a fuse rated I , as a function may appear across fuse terminals as
N
of the RMS current I, in multiples of I , in function of working voltage U at cos ϕ = 0.15
N
a steady state.
SCAC84 12/04
