Page 249 - Ferraz semiconductor DIN

Semiconductor fuses
Semiconductor (AC) fuses

®
Protistor Square-body Fuses
PSC aR sizes 7x - 650 V to 1300 VAC
Curves set

Multiplier coefficient

2
2
Left: Mean curve indicating variation of total I t (I t )
t
K 1,4 and total operating time T in accordance with
t
working voltage U.
1,2 *
Example:
1 Fuse 350 A in size 70.
I = 10 000 A U = 1100 V
p
0,8
At 1000 V
2
2
I t = 115 000 A s T = 7 ms
0,6 t t
At 1100 V
0,4
I t = 115 000 x 1.13 = 130 000 A s
2
2
t
T = 7 x 1.13 = 7.9 ms
t
0,2
* curve for fuses with I t published at 850VAC
2
0
0 200 400 600 800 1000 1200
U (V)
Dissipated power Arc voltage
P/Pn

I/In

Above left: Curve enabling calculation of Above right: Curve indicating peak arc
dissipated power P by a fuse rated I , as a voltage Um which may appear across
N
function of the RMS current I, in multiples fuse terminals as a function of working
of I , in steady state. voltage U at cos ϕ = 0.15
N

SCAC134 12/04