Low
voltage aerial power lines use
uninsulated wires, as they
rely on their wide spacing to provide the necessary insulation. However,
wind can blow the wires together,
or branches can bridge the gaps,
resulting in sparks that can ignite
bushfires. To reduce this problem, the three phase wire plus earth wire
are insulated and then wrapped together.
Now dangerous sparks cannot occur.
Unexpected energisation of a circuit pressured
to be isolated
To help reduce the negative effects of shorts
circuits, power distribution transformers are deliberately
designed to have a
certain amount of leakage reactance. (Usually about 5 to 10 % of the full load
impedance) helps limit both the magnitude and rate of rise of the fault
current.
A short circuit
may lead to formation of an arc; the arc a channel of hot ionized plasma, is
highly conductive and persist even after significant amount of original
material of conductors was evaporated. Surface erosion is a typical sign of
electric are damage. Even short are can remove significant amount of materials
from the electrodes. The temperature of the resulting electrical are is very
(tens of thousand) of degrees Fahrenheit, causing the metal on the contact
surface to melt, pool and migrate with the current, as well as to escape into
the air as fine particular matter.
POSSIBLE SOLUTION
FAULT
FINDING EXPERTISE
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To avoid putting your or your staff at risk by ignoring
electrical faults.
-
To it’s
essential to ensure that any appliances you purchase are approval by
underwriters Laboratories (UL) or another reputable consumer Laboratory.
-
Unplug unused appliances and stow cords safety out of
reach of pets, young children or hazardous situation.
-
Appliances that generate heat, such as clocks,
televisions and computer monitors, should be given several inches of clearance
all round for good air circulation and cooling. Do not drape clothes, toys or
other items over warm appearance
*
Always follow appliance instructions carefully,
and do not attempt amateur, repair or upgrades.
*
Keep all electrical appliances away from water
such as Sikes, bath tubes, pools or over head vents that may drip.
*
Do not operate any electrical appliance with wet
hand or while standing in water.
*
Keep clothes, curtains, toys and other
potentially combustible materials at away from radiators, space heaters,
heating vents and other heat sources.