Above the standard

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For power-critical commercial buildings such as process plants, industrial infrastructure, data centres as well as hospitals, airports and tunnels, a continuous supply of electrical power is essential.

The provision of reliable power in such buildings is reliant upon the low-voltage distribution panels that lie at the heart of the electrical installation. The demands placed upon these panels, particularly as operations and infrastructure expand over time, leaves them intensely vulnerable to arc faults.

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 €40,000 [around £35,00] in 24 hours. Then there is the cost of replacement switchgear, potential legal action and reputational damage on top of that. In short, people, property and business continuity are all put at serious risk both in the immediate timeframe and the longer term.

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/EN 61439 standard.

However, research suggests that compliance with the standard may not be sufficient to maximise protection, but 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/EN 61439, as well as other relevant standards.

In a whitepaper commissioned by Eaton, Safety and Risk in Electrical Low-voltage Installations, electrotechnical safety expert Alfred Mörx, explains: “The purpose of the planning and execution of low-voltage installations is to achieve safety while excluding risks.”

What this means is that building owners and managers must ensure that any risk that remains after protective measures have been put in place, must be as low as possible and does not exceed “the highest acceptable risk.”

Risk of arc fault

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 risk of an arc fault occurring increases, not only destroying valuable property and assets, including the installation, but also severely disrupting business continuity and potentially endangering lives.  

Arc faults can also be triggered during maintenance or expansion projects when, by accident, conductive parts drop on the busbars while working on the panel. This is a life-threatening scenario for any personnel in the vicinity of the incident. However, it is also possible for a devastating arc fault to be triggered by something as simple as a small animal crawling into the panel, and there are documented cases to prove it.

Partial or complete destruction to the power distribution system will inevitably lead to business interruptions, which can last days, weeks or even months. The longer the interruption, the more the consequential damages. 

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 resources and products can no longer be used. 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 provides a detailed economic assessment of the total costs that businesses can face in the event of an arc flash incident, represented in an estimated costing per hour of downtime for typical applications.

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.

It’s also worth bearing in mind that the typical replacement cost for a panel quickly reaches the few hundred thousand Sterling mark, while sourcing and installing replacement parts can easily take a few days up to weeks. During that time, the facility is effectively out of action.

State of the art technology

While businesses need only meet the minimum requirements set out in IEC 61439, Article 6 (2) of the EU Directive 89/391/EEC, it stresses that employers should consider ‘state of the art’ technology to create safe working conditions. 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.

According to Mörx: “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. If additional action is taken, the extent of damage in the installations and/or business interruptions with considerable consequential damages can be reduced. The same applies to any health impairments of employees that work in or near plants. The low-voltage switchgear assemblies equipped with additional measures have some kind of ‘safety reserve’.”

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 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 and respond accordingly, 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 aseembly 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?

Bernhard Gegenbauer is power distribution product manager at Eaton

Whitepaper: Complying with EN 61439 guidelines here


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