Wednesday, March 19, 2014

Single phase and three phase faults effects on human body and human body perception level

Can ever imagine how dangerous are electrical faults???

Let me give you one fact about electrical faults and their levels.

Temperature produced during electrical arc-flash can reach 35,000 _F (19,500 _C).
 These extremely high temperatures will easily melt copper conductors.

Copper expands by a factor of 67,000 times at such high temperatures
Usually such faults occurred during Short circuit of copper bus bars.
When Human comes directly short circuit with two phases.

The dangers associated with these faults are:-

1. High pressures
2. High level of Sound
3. Very high currents

These high pressures can easily exceed 100-1000  pounds per square foot. Such faults produce high sounds which seems like a bomb get blasted and even causes damages to ladders, Humans etc.

The sounds associated with these pressures can exceed 160 dB.

The electrical current levels associated with electrical shock are measured in milli-amperes or one-thousandth of an ampere (0.001 Amps).

Electrical current flows through the body’s nervous system, muscles, and the blood system. Current flow
can damage organs , Can cause burning of body and have long-term effects on the body, which may not be readily visible at the time of the shock event.

HT Fault currents are such high that immediately all body get burnt in seconds and only ashes remains

Electrical shock current levels:-
Current range (mA) Physiological effect Condition description:-

1mA Threshold of perception Detect a slight tingling sensation in hands or fingertips

1–9 mA       Let-go threshold:- Unpleasant sensation but muscle control not impaired.
9–25 mA     Muscular contraction:- Painful and hard or impossible to release energized object in hand
26–59 mA   Muscular contraction Breathing difficult

60–100 mA Ventricular fibrillation Heart stoppage, respiration inhibition, death possible