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Installation
3.
Aluminum wire is not recommended due to soft metal migration at the terminals,
which may cause long term (on the order of years) poor connections and
oxidation. If used, increase the wire gauge by two sizes (e.g., specify 10 gauge
aluminum instead of 14 gauge aluminum).
4.
Derate the above wire gauge (use a heavier gauge) for higher environmental
temperatures since conductor resistance increases with temperature.
Temperature
40°C, 104°F
5.
Derate the above wire gauge (use a heavier gauge) for an increased number of
current carrying conductors. This offsets the thermal rise of bundled conductors.
Number of
Conductors
3 to 6
Above 6
6.
The preferred insulation material is application dependent. Elgar's recommend-
ation is any flame retardant, heat resistant, moisture resistant thermoplastic
insulation rated to a nominal 75°C (167°F). Voltage breakdown must exceed the
combined effects of:
•
The rated output voltage;
•
Transient voltages induced onto the conductors from any source;
•
The differential voltage to other nearby conductors; and,
•
Safety margins to accommodate degradations due to age, mechanical
abrasion, and insulation migration caused by bending and temperature.
7.
As frequency increases, the magnetic field of the current carrying conductors
becomes more significant in terms of adverse coupling to adjacent electrical
circuits. Use twisted pairs to help cancel these effects. Shielded twisted pairs
are even better. Avoid close coupling with nearby cables by using separate
cable runs for high power and low power cables.
8.
The above general values and recommendations should be reviewed, modified
and amended as necessary, for each application. Cables should be marked with
appropriate safety WARNING decals as hazardous voltages may be present.
2-18
Current Capability
80%
Current
Capability
80%
70%
SW 5250A•SW 3500A•SW 1750A
Operation Manual
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