A short circuit is dangerous and could cause fire, devices damage or even human injury and death. This is because its two effects, Mechanical and thermal effects.
When a
short circuit condition begins a large amount of
electrical current passes through the electrical system starting from
generator passing through
cables and devices of the circuit and ending to the fault location. This
current value is in Kilo Ampere which is much larger than normal current.
This kilo ampere current produces high temperature large enough to destroy the faulty device and to melt
copper conductors,
circuit breakers contacts and almost any thing in its way.
Mechanical damage of short circuit (SC)
The current flow during the fault condition in the bus bar has a reverse direction than the normal flow direction. This causes a repel condition between the faulty bus bar phase and the normal one. This could cause bolts and other parts to fly away in air in dangerous condition.
Why do short circuits cause fire?
When current passes through an electrical conductor it causes a rise in temperature. This rise depends on the
conductor resistance and the current value. Th larger the current value the higher the temperature. As mentioned above that the temperature rise is one of two main factors which are the answer of the famous question, Why is a short circuit dangerous?
If the protection device fail to
isolate power of faulty load, Then the current of the SC could be very high and produce more and more temperature rise. This rise is enough to cause fire.
Protection against short circuit danger
As mentioned above
short circuit is dangerous and must be taken into account when designing any electrical system. The protection devices are
fuses,
circuit breakers and advanced
protection relays. Fuses and circuit breakers are mostly used. While protection relays are used in industrial loads and
switch-gears.
