The risks of an electrical arc and the possibilities to nullify the damage completely
Arc Flash can present high risks, but there are ways to prevent them
?Accidents with electricity, including electric shocks, fires due to overload and other discharges, reached the mark of 759 occurrences in the first half of 2021, according to recent data from the Brazilian Association for Awareness of the Dangers of Electricity (Abracopel). These data confirm a reality, that energy, whatever it is, is dangerous and can cause serious consequences.
Given this information, it is necessary to consider possible situations that can cause risks such as those mentioned above and to know the best way to deal with them, in case of an electric arc occurs.
When an electric current flows between two points where insulation loss and dielectric breakdown has happened, there is not only visible energy liberated. In this situation, many waves of different lengths occur. “For this phenomenon to happen, it is necessary to have two conductive electrodes, that is, two points with potential difference, and between them a gas or an insulator that suffers a dielectric breakdown capable of breaking the insulation producing a discharge", explains Castellane Ferreira Engineer and director of Varixx, manufacturer of solutions for power electronics.
Among the various risks offered by electrical energy, the electric arc stands out as one of the most dangerous for operators and those involved in electrical maintenance. Because of to the large amount of energy released and the high temperatures generated by this phenomenon, workers can suffer serious burns or even risk of death. Also, its effects are even broader, as toxic metal fumes, projection of molten metal, intense light and a pressure wave are generated.
"In addition, the emitted light and the frequency spectrum of the electric arc include ultraviolet ray radiation, which can cause damage to the ocular retina of a human being," Ferreira explains.
The electric arc can generate a heat so intense that it reaches up to 20,000 °C, a temperature higher than that supported by any known material. Therefore, it can also cause irreparable damage to machines, equipment and the environment, causing economic losses and socio-environmental responsibility.
The faults that originate an electric arc are associated, in most cases, with phase-earth fault, which can suddenly evolve into a three-phase fault, and the most common causes of these faults are tool falls, accidental contact by maintenance personnel, corrosion or dust accumulation on conductors, aged insulators, and the presence of pests such as rats, snakes or other animals that come into contact with energized conductors, which can produce intense heat, explosions, pressure waves, and other effects. By releasing a large amount of energy in a short period of time, the electrical arc has come to be considered one of the main risks involving electricity.
“Daily here at Varixx, industries or companies of all sizes and diferents business segments come to us to report events involving electrical arcs. Many times, these same industries wait until something really serious to happen before they start acting, and when something of this level happens, electrical substations with several electric panels and switchgears are destroyed, impacting the production process and, even more drastic, taking people’s lives”, comments Ferreira.
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?HOW TO MINIMIZE THE EFFECTS OF ELECTRIC ARC?- In fact, companies used to provide protective clothing as a good way to minimize the effects of arc flash on electrical facilities workers. However, for operations in high-risk areas, often the level of protection of the PPE was not enough to protect these people's lives.
The regulatory standard NR-10, Safety in Facilities and Services in Electricity, presents a set of measures that if put into practice reduce the possibility of a worker suffering the consequences of an electric arc. From de-energizing the panel to the use of CPEs and PPEs, collective and individual protection measures that help to prevent an electric arc from happening, or to minimize its consequences.??
In this way, much research has brought technical information on how we can reduce the effects of arc flash or how we can reduce the incident energy generated by this event. For a long time, researchers have developed the pyramid of control hierarchy with a step-by-step approach to reduce and protect people in electrical substations or other high-risk areas.?Eliminating the risks is the first step. The second is to replace old equipment with newer, higher-performance equipment, efficients and reliable, which is applied for circuit protection and opening systems, such as a circuit breaker, for example. After these, the next step is the engineering analysis and the last step is the PPE specification.????
About engineering analysis control, Ferreira, claims that among the existing measures are protection systems that detect electrical arcs through ultraviolet waves produced in the initial stage of arc ionization. These systems are able of opening circuit breakers and shutdown quickly after identifying an arc in anticipation, acting in an ultra-fast time. Therefore, reducing the incident energy on electrical facilities and substation.
The innovative pre-arc time detection mode and ultra-fast actuation in a maximum of 300 microseconds has been introduced for the first time by Varixx. The Zyggot Arc, realizes this detection that eliminates the need for an electrical current reading to confirm the arc event. This is possible due to the detection by ultraviolet wave that also brings more reliability, because during the consolidation process of the initial stages of an electric arc, there is an abrupt increase of the ultraviolet wave in the air ionization stage.
"As a result, Zyggot's innovations are considered one of the best in the market, because they increase safety, minimize damage to equipment, and prevent risks involving the professional lives." Ferreira says.
Electric energy is a risk, not only for the lives of employees working in the area, but also for the entire infrastructure of a company and also for its corporate image associated with the bad exposure resulting from accidents at work. Therefore, pay attention to the sign and take preventive measures, so that they do not need to be applied after an accident has happened.