Information

In the following some examples are
given:
Example 1
Problem:
What current is required to increase
the temperature by 200°C of
ISA13
®
wire with a diameter of
0.20mm?
Solution:
a) From the table can be seen
that the value for ISOTAN
®
wire with equal diameter is
1.03 Amps.
b) This value must be converted
for ISA 13
®
in accordance with
the previously quoted formula;
this results in
i
x
=
⋅03.1 =
13.0
49.0
Amps2
94.103.1
≅
⋅
where 0.49 is the resistivity of
ISOTAN
®
and 0.13 the
resistivity of ISA13
®
, at 200°C,
resprectively.
Result:
An ISA13
®
wire with a diameter of
0.20mm must be loaded with a
current of 2 Amps in order to
increase its temperature by 200°C.
page 9
Example 2
Problem:
What is the temperature increase of
ISA-CHROM 60
®
wire with a
diameter of 1.0mm, if it is loaded
with a current of 8 Amps?
Solution:
a) In accordance with the
previously quoted formula, for
20°C the conversion factor for
ISA-CHROM 60
®
alloy is
calculated to be
664.0
11.1
49.0
)1
=
b) In order to get the load value
for ISOTAN
®
wire with equal
diameter, the value for ISA-
CHROM 60
®
must be divided
by this value, thus
Amps
Amps
i
ISOTAN
12
664.0
8
==
This results in a value of 12 Amps
for ISOTAN
®
alloy.
If an ISOTAN
®
wire of equal
diameter is loaded with the
calculated 12 Amps, its temperature
will increase by somewhat less than
400°C. As can be seen from the
table on page 8, an
overtemperature of 400°C is
achieved by applying a current of
12.3 Amps.
The conversion factor determined
as per a) applies to 20°C; it must
now be re-determinded for 400°C. It
is 0.644, resulting from
)1
18.1
49.0
where 0.49 is the resistivity
of ISOTAN
®
and 1.18 that of
ISA-CHROM 60
®
, at 400°C,
respectively.
Now if the load current of 8 Amps
for ISA-CHROM 60
®
at 400°C is re-
calculated for ISOTAN
®
, a value of
12.4 Amps for ISOTAN
®
wire with
equal diameter will result. Since for
400°C a value of 12.3 Amps
applies, one gets the following:
Result:
If an ISA-CHROM 60
®
wire with a
diameter of 1.0mm is loaded with a
current of 8 Amps, its temperature
will increase by somewhat more
than 400°C.
.
1)
These values apply to a state after rapid cooling