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Arc Flash Analysis: an essential factor for safety

Trace Software International announces that the elec calc™ Arc Flash module has been just released. The company possesses a  unique passion for the design of high-performance software solutions for electrical engineering since 1987.

What is an Arc Flash?

According to the NFPA 70E (the relevant standard from the National Fire Protection Association), Arc Flash is a “dangerous condition associated with the release of energy caused by an electrical arc.”

Arc flash typically occurs when the electrical insulation or isolation between live conductors is severed or can no longer withstand the applied voltage. Near the high power electrical equipment, the short-circuit power available is high and consequently so is the energy associated with the electrical arc in case of a fault.
In Europe, regulation and standardization are mainly aimed at protecting workers against the risks of direct contact during work and interventions on and near electrical installations. The risks in the case of electric arc and the means to prevent them are mentioned but not developed.

In some countries, particularly in North America, these risks are better taken into account for human, material and financial aspects, and regulations are much more stringent in this area.

The effects of the electric arc:

  • The electric arc produces intense light and heat, high noise, high overpressure
  • Heat and splashes of molten metal can cause lethal burns
  • Noise can lead to permanent or temporary hearing loss, a flash of vision disorders
  • The overpressure can open and project the doors of electrical cabinets or cause falls during work at height

In addition to personal injury, an arc flash can result in serious damage to electrical equipment. which can cause disruption to electrical systems in manufacturing and process industry environments or tertiary buildings. The cost of downtime can be considerable.

Risk assessment and arc flash analysis

There is no method of analysis and risk assessment by IEC or European standards. In contrast, the United States has the following documents:

  • NFPA 70E (Standard for Electrical Safety in the Workplace) takes into account all electrical risks including those due to electric arcs recommends PPE (Personal Protective Equipment) to be used depending on the level of risk
  • IEEE 1584-2018 (Guide for Performing Arc-Flash Hazard Calculations) gives the methods to calculate the incident energy in case of electric arc  and allows determining an arc flash protection boundary

 

The elec calc™ arc flash module by Trace Software International

 

elec calc™ Arc Flash module

Risk management and prevention have always been important aspects of the safety programs within the electrical industry. The correct assessment of the risk level of the arc flash can help reduce downtime and ensure a safer working environment.
The arc flash module provides the professionals of the electrical industry with a fundamental tool in the sector, as the user will be able to develop its safety analysis in the vicinity of switchboards and panels. By design, elec calc™ has almost all the data allowing the calculation of the figures of the arc flash, from which the user will be able to elaborate his security analysis near the tables and boxes.
From the operating modes described in a project, elec calc™ determines the maximum and minimum three-phase short-circuit currents that can occur on a distributor. It calculates the corresponding cut-off times of the concerned protective devices. Specific data of the equipment can be completed or modified by the user through a simple interface.
The following results are provided according to the calculation methods of the IEEE 1584-2018 guide (empirically derived model or method of Lee depending upon the characteristics of the installation):

  • The maximum incident energy at the working distance
  • The protection boundary for the boundary energy
  • The glove class (PPE) to be used to prevent the risk of electric shock (IEC 60903 and ASTM D 120)

Warning labels

elec calc™  allows the edition of the labels to be affixed on the concerned equipment or the export of the corresponding results to make possible the customization of the labels. The format of the label is consistent with the recommendations of the document NFPA 70E (edition 2018).
In addition, elec calc™ monitors the evolutions of the installation and prevents the obsolescence of previously published labels.
Trace Software International commits itself to conceive software solutions capable of guaranteeing electrical safety and system protection. More than 30 years of experience in the industrial engineering sector has allowed us to guarantee the highest standards of quality and reliability, as well as the complement of local and international regulations in terms of safety.

 

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The lighting protection by Trace Software International

The lightning protections

Lightning protection systems are used to prevent or reduce lightning strike damage.

According to NASA, there are 2,000 thunderstorms active all over the world at a given time and produce about 100 flashes per second. The number of annual lightning fatalities is difficult to estimate, ranging from 6 000 to 24 000 depending on the different studies; this not counting tens of thousands of injuries and millions of dollars in property damage.

 

Different scenarios may occur:

– The lightning strikes a structure directly
– Lightning strikes the ground adjacent to the structure
– Lightning strikes services connected to a structure such as, for example, power cables
– Lightning strikes the ground near services connected to a structure

 

 

Lightning protection by Trace Software International

 

 

When lightning reaches the earth, it generally does so directly on natural elements (trees, hills, water, etc.) but also occasionally on structures, buildings, pylons, and other artificial structures. This is a distinction that leads to the division into two distinct types of effect. Those described as “direct” that is due to the circulation of the current that heats the materials and those “indirect” that produce overvoltage by conduction, induction or increase in earth potential.

 

Direct

 

– Electric. This refers to electric voltages created by electric shocks when a certain field is struck by lightning. The occurrence of this event usually leads to fires.

– Thermal. The effect will be linked to the resistance of the affected material. There is a strong release of heat which causes a very high localized pressure. The consequences are fires or the melting of equipment.

– Electrodynamic. Near the place of passage of the lightning, the current appears a strong magnetic field generating voltages and induction currents on any conductive element located in its immediate field of action. Induced mechanical forces can cause deformation, tearing, destruction.

– Electromagnetic. Lightning current induces an extremely high voltage and an extremely strong electromagnetic field that generates very powerful electrical impulses that can damage sensitive electronic devices.

– Physiological. From nervous shocks to blindness or death, there are numerous damages that lightning can cause to the human being.

 

Indirect

 

– Conduction: a surge that propagates along a conductor who has been in direct contact with the lightning. This effect is all the more destructive as most of the lightning energy is propagated across the entire network. This problem is solved by installing the installation with a suitable surge arrester.

– Induction: caused by the electromagnetic field radiated by lightning. It generates an overvoltage on the conductors proportional to the steepness of the lightning current rise. As a result, under the influence of sudden changes in current, cables and even conduits acting as antennas can be subjected to destructive overvoltage. This is why the placement of the underground network does not guarantee lightning protection.

 

Risk management includes the calculation of the potential hazards caused by lightning and provides the basis on which to make decisions to limit the disastrous consequences. Firstly, for a comprehensive risk analysis, it is necessary to take into account different factors: local meteorological risks, territorial morphology, the nature of the structures to be protected, the activities carried out, the fragility of the equipment, the strategic level of the plants, the rate of acceptable failure, etc.
There are various methods of risk analysis for this, which also vary according to national directives. The primary purpose of lightning protection is to protect buildings against direct lightning and the possible risk of fire or the consequences of lightning currents.

 

 

Lightning protection by Trace Software International

 

In Europe, the “Lightning Protection Standards EN 62305-1 to 4” dictates the guidelines on lightning protection. The first section mainly contains information on the risk as well as the characteristics of the phenomenon. The second section, on the other hand, is dedicated to risk management, thus also determining mandatory protective measures from both an economic and technical point of view, up to a tolerable level of risk. In the third section, the normative talks about the protection of structures and people from material damage and lethal situations caused by the lightning current. In these situations, a lightning protection system is external (external protection, air termination system, down-conductor system, and grounding) and internal (lightning equipotential bonding and separation distance). The fourth section talks about the necessary protection measures against the effects of the eventual occurrence of an electromagnetic field.

 

A special case of photovoltaic installations

 

In France, the standards and guides related to photovoltaic installations specify the measures to be implemented to provide protection against overvoltage of atmospheric origin or due to switching. It is also stated that, regarding the sensitivity and location of photovoltaic modules, particular attention should be paid to protection against the direct effects of lightning, especially for large installations.
For this purpose, standard NF C 15-100 proposes a simplified risk analysis taking into account, among others, the density of lightning, the type of installation, the type of power supply, the presence of lightning rods and the probability of risk to the safety of people and property.

 

archelios™ calc software by Trace Software International

 

archelios™ calc integrates this simplified risk analysis to check the adequacy of the surge arresters to be used in the photovoltaic system. This verification is mandatory for installations designed according to French standards and optional for those made with the IEC standard.

 

With the contribution of Philippe Au Petit – elec calc™ Product Manager at Trace Software International

 

 

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Tracesoftware – Empowering electrical solutions.

Check out: Webinars    eSHOP    Sales