Electric Shock and Preventive MeasuresGirish KR
An electric shock is the pathophysiological impact of an electric flow through the human body. Electric flow basically affects the muscular, circulatory, and respiratory functions and once in a while brings about extreme burns to the human body. The level of risk to the casualty depends on the currents magnitude, the parts of the body through which the current passes, and the span of the current.
At the point when a current surpassing 30 mA goes close to the heart of a human body, the individual concerned is in imminent danger if the current isn’t interrupted within a brief timeframe.
Different measures are followed to ensure protection against electrical shocks, and they include:
Automated connection cut of the power to the associated electrical equipment.
Special arrangements are used such as:
- The utilization of class insulation materials
- Non-conducting location, out of arm’s reach or interposition of barriers
- Equipotential bonding
- Electrical separation by methods of isolating transformers
Contact with live part (Direct contact)
When an individual coming into contact with a conductor that is live in typical conditions. The security to be executed in these conditions is known as “Basic Protection”
Contact with conductive parts in fault conditions (Indirect contact)
When an individual comes in contact with an uncovered conductive-part that is not usually live yet has become live unintentionally (Maybe because of failure in insulation or to some other cause).
This fault current raises the exposed conductive part to a voltage that is responsible for the damage as it generates a touch current through an individual coming in contact with exposed-conductive-part.
The protection that is reinforced in such conditions is referred to as “Fault Protection”
All the former protecting measures are preventive, however, experience has indicated that for different reasons they can’t be viewed as being faultless. Among these reasons may be cited as:
- Lack of proper maintenance
- Imprudence, carelessness
- Normal (or abnormal) wear and tear of insulation; for instance flexure and abrasion of connecting leads
- Accidental contact
- Immersion in water, etc. A situation in which insulation is no longer effective
In order to protect users in such circumstances, highly sensitive fast tripping devices, based on the detection of residual currents to earth are used to disconnect the power supply automatically, and with sufficient rapidity to prevent injury to, or death by electrocution, of a normal healthy human being.
These electrical devices work on the principle of residual current measurement, in which any contrast between the current entering a circuit and that leaving it is flowing to earth, either through defective insulation or through contact of an earthed part, such as an individual, with a live conductor.
Standardized residual current gadgets, called as RCDs, adequately sensitive for protection against contact with live parts are appraised at 30 mA of residual current. The reaction time is sufficiently quick to offer protection.
An Earth-leakage electrical switch (ELCB) is a safety gadget utilized in electrical establishments with high earth impedance to prevent shock. It distinguishes small stray voltages on the metal enclosures of electrical devices and stops the circuit if a harmful voltage is found out. The recent installations opt for residual-current devices (RCDs, RCCBs, or GFCIs) which rather identify leakage current directly.
The Earthing or Grounding is the security given to every single electrical framework. Earthing is a significant consideration in protecting the electrical framework from internal and external causes. The internal causes include switching surges, current overflow and voltage, fault current, and so forth, and the external causes include lightning.
ELCBs have one advantage over RCDs:
- They are less delicate to fault conditions and accordingly have fewer nuisance trips.
- While voltage and current on the earth line generally is a fault current from a live wire, this isn’t generally the situation, along these lines, there are circumstances wherein an ELCB would cause a nuisance trip
Advantages of ELCB over RCCB
One significant advantage of ELCB over RCCB is that it is less sensitive to fault conditions when compared to RCCB, henceforth it has fewer events of nuisance tripping.
ELCB: The purpose of its use?
An Earth Leakage Circuit Breaker is a safety device utilized in Electrical circuits with high Earth impedance to forestall the danger of Electrical shock. ELCB is a voltage-operated gadget.
ELCB identifies small stray voltages across metal enclosures of electrical establishments and interrupts the circuit if the voltage level surpasses the threat limit.
ELCBs were invented almost 60 years ago and once utilized in electrical establishments. However, since the invention of RCCB- an improved protection device, the utilization of ELCBs has descended.
Thus, the main purpose of ELCB is to detect Earth leakages and prevent injury to human beings from electrical shocks.
In this way, the principle motivation behind ELCB is to distinguish Earth leakages and prevent harm to people from electrical shocks.