WCN Autumn 2010

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WCN Issue N° 43 28
due to its lower carbon content,
which enhanced diffusion of iron and
zinc. Besides carbon, other alloying
elements could have an influence on
diffusion and consequently temperature
resistance time.
Wrapping Tests
Figure 12 shows wrapping tests of
the 3.4mm Zn and Zn5Al coated 1083
core wires taken from the ACSR cable
segments after 185 days at 190°C.
These tests were done by wrapping
the wire around mandrels having
1, 2 and 3x the wire diameter.
At this and at all lower time durations,
no coating failures were seen in any of
the Zn or Bezinalized core wires.
For the 1.85mm 1005 wires, failures
were noticeable in the case of the Zn
coated wire, but not with the Zn5Al
coated wire ( Figure 13).
The Zn coated 1.85mm 1005 wire
can be seen to become progressively
worse with time at 190°C as shown in
Figure 14 .
At higher temperatures, defects in
coatings on the 3.4mm wires from 1x
wrapping tests are noticeable, starting
at 225°C after 14 days as shown in
Figure 15 .
Similar defects were seen with 3x
wrapping conditions.
Under these conditions, small ruptures
begin to appear in the Zn coating. No
ruptures are seen in the Zn5Al coating,
but a ‘crosshatch-like’ texture begins
to appear on the Zn5Al coating which
is believed not to be due to coating
failure, but is believed to be due to
brittleness in an oxidized Zn-Al ‘skin’
developed on the coating during the
high temperatures.
Similar wrappings for 3.4mm 1083 after
28 days at 225°C show no significant
differences from those exposed for
14 days at the same temperature.
Figure 16 shows 1x wrappings for the
1.85mm Zn and Zn5Al coatings after
two and four weeks at 225°C. No
damage is seen for either coating after
two weeks, but the Zn coating clearly
Figure 12 ▲
▲ : 1x, 2x and 3x wrapping tests for 3.4mm
1083 ACSR core wires after 185 days at 190°C
Figure 13 ▲ ▲ :1x wrapping tests for 1.85mm 1005
wires after 185 days at 190°C
Figure 14 ▲ ▲ : 1x wrapping tests for 1.85mm
Zn-coated 1005 wire after 62 and 121 days at
185°C
62 days
2 weeks
4 weeks
121 days
Zn
Zn5Al
Zn
Zn5Al
Figure 15 ▲
▲ : 1x wrapping tests for 225°C 3.4mm
1083 conditions, 2 magnifications
Figure 16 ▼ ▼ : 1x wrappings of 1.85mm trials at
225°C, two and four weeks, at two magnifications
2 weeks
2 weeks
4 weeks
4 weeks
Zn
Zn5Al
Zn
Zn5Al
Zn with Al
conductors
Zn without
Al conductors
Zn5Al with Al
conductors
Zn5Al without
Al conductors
Figure 17 ▼
▼ : 1x wrappings of 3.4mm 1083 wires
after 245°C, 14 days with and without aluminium
conductors