An arc fault in an electrical distribution panel is difficult to ignore. A massive build-up of pressure within the panel, rising to 25 tonnes per square metre, leads to what can only be described as an explosion, sending components flying through the air, destroying the installation and threatening the life of anyone nearby. If that initial blast is not damaging enough, the aftermath brings further risks, with the prospect of lengthy downtime.

New research commissioned by Eaton estimates that for a typical food industry plant, the cost of production downtime alone could escalate to $46,000 in 24 hours. Then there is the cost of replacement switchgear, potential legal action and reputational damage. Despite these palpable dangers, electrical distribution panels are easy to overlook in a safety analysis of commercial building infrastructure. The equipment is generally tucked out of sight and the prevailing view is that switchgear is absolutely safe as long as it conforms with the requirements of the (International Electrotechnical Commission’s) IEC 61439 standard. Eaton suggests that a higher level of safety can be achieved with the implementation of new technologies. As a result, it’s possible to further reduce the risk of a catastrophic arc fault and its costly aftermath.Low-voltage electrical distribution panels are the beating heart in the supply of electrical power. Building owners and managers have a legal obligation to ensure that the switchgear assembly that drives processes meets the requirements set by the IEC, the international standards and conformity assessment body for all fields of electrotechnology. Business must ensure by law that equipment is planned, built and tested to the relevant version of the IEC 61439 standard. In a whitepaper commissioned by Eaton, Safety and Risk in Electrical Low-voltage Installations, electrotechnical safety expert Alfred Mörx, says “the purpose of the planning and execution of low-voltage installations is to achieve safety while excluding risks”.



However, even businesses that meet their legal duties are not immune from the risk of arc faults. Over time, energy intensive companies may expand operations, adding new installations on to existing systems. The end result is that the switchgear assembly can overload causing an arc flash, not only destroying valuable property and assets, including the installation, but also severely disrupting business continuity and potentially endangering lives. In some cases the cause may be that the chosen switchgear is wholly unsuitable for the chosen application, which can cause dangerous levels of overheating. In other cases, an arc fault can arise from incorrect operation, insufficient servicing or unsuitably hot or humid operating conditions.

Arc faults can also be triggered if a maintenance engineer drops a conductive tool on the busbars while working on the panel. This is the scenario, during installation or maintenance work, when life safety is most seriously jeopardised. But, it is also possible for a devastating arc fault to be triggered by something as simple as a small animal crawling into the panel. Partial or complete destruction to the power distribution system will inevitably lead to business interruptions, which can last days, weeks or even months. Commercial buildings with critical power needs are especially vulnerable to power failures. System reliability and continuity of power supply are vital. After all, the sudden loss of power midway through an industrial process could mean that valuable products need to be destroyed. It wouldn’t take long for the cost of the original fault to mount significantly, and there could be environmental outcomes too if hazardous substances or materials need urgent disposal. The whitepaper states that the total consequential damages for a 24-hour period, including loss of profits, cleaning and restart costs and additional costs such as penalties for failing to keep delivery dates, could amount to $46,000. The calculation is based on an average production or filling facility in the food industry, and shows how the costs rise exponentially hour by hour.

While businesses need only meet the minimum requirements set out in IEC 61439, Article 6 (2) of the EU Directive 89/391/EEC stresses that employers should consider ‘state of the art’ technology to create safe working conditions. According to Mörx, ‘state of the art’ technology such as arc fault protection is a key measure that employers can take to reduce possible consequential damages and enhance employee protection while also going beyond the minimum requirements. Mörx says: “Switchgear assemblies that only fulfil the minimum requirements are very likely to fall below the highest acceptable risk in the direction of hazard when an event occurs.”

To maximise safety, two of the most effective strategies are firstly to monitor for unusual temperature rises that could indicate an imminent fault and secondly to ensure that, in the event of an arc fault, the event is identified in real-time in order to rapidly shut down the switchgear and minimise damage to the panel itself and also any connected equipment.

In temperature monitoring, the traditional use of thermal imaging provides a limited snapshot that doesn’t necessarily cover all of the main areas of the panel, including in some cases the crucial bus bars. However, new technology from Eaton continuously monitors temperature trends at critical points and sends data wirelessly to a separate controller, enabling engineers to analyse heat levels of a selected period of time and conduct further investigations or preventative maintenance work accordingly.

In order to ascertain the level of risk, Eaton recommends that relevant stakeholders in power-critical commercial buildings ask themselves a series of searching questions: What are the technical impacts of a failure to the switchgear assembly? How high are the consequential damages? What are the possible effects of a failure of the switchgear assembly on the employees ensuring servicing? How heavy is the damage to the company’s image because delivery times cannot be kept? What are the impacts of a failure of a switchgear assembly on the environment?


SOURCE:

https://www.mepmiddleeast.com/72021-how-to-guard-against-electrical-safety-risks