SIDACtor
Data Book
Fuse Selection Criteria
Teccor Electronics
(972) 580-7777
5 - 7
T
8$
Because fuses are rated in terms of continuous voltage and current carrying capacity,
it is often difficult to translate this information in terms of peak pulse current ratings. In
an attempt to simplify this process, Teccor has worked with several fuse manufacturers
to compile Table 5-1.
Table 5-1:
Notes:
1. The I
PP
ratings apply to a 2AG slow blow fuse only.
2. Because there is a high degree of variance in the fusing characteristics, the I
PP
ratings listed should only be
used as approximations.
When selecting a fuse the following criteria should be used:
Peak Pulse Current (I
PP
)
For circuits that do not require additional series resistance, the surge current rating
(I
PP
) of the fuse should be greater than or equal to the surge currents associated with
the lightning immunity tests of the applicable regulatory requirement (I
PK
).
I
PP
≥
I
PK
For circuits that utilize additional series resistance, the surge current rating (I
PP
) of the
fuse should be greater than or equal to the
available
surge currents associated with
the lightning immunity tests of the applicable regulatory requirement (I
PK(available)
).
I
PP
≥
I
PK(available)
The maximum available surge current is calculated by dividing the peak surge voltage
(V
PK
) by the total circuit resistance (R
TOTAL
).
I
PK(available)
= V
PK
/R
TOTAL
For longitudinal surges (TIP-GND, RING-GND), R
TOTAL
is calculated for both Tip and Ring.
R
SOURCE
= V
PK
/I
PK
R
TOTAL
= R
TIP
+ R
SOURCE
R
TOTAL
= R
RING
+ R
SOURCE
For metallic surges (TIP-RING):
R
SOURCE
= V
PK
/I
PK
R
TOTAL
= R
TIP
+ R
RING
+ R
SOURCE
Equivalent I
PP
Rating
10X560μs
(A)
15
25
30
35
45
65
85
115
Fuse Rating
(mA)
250
350
400
500
600
750
1000
1250
10X160μs
(A)
30
45
50
65
75
90
130
160
10X1000μs
(A)
10
20
25
30
35
50
65
100