Arc faults have been a hot topic in the electrical industry for more than a decade, with much of the discussion centred on aging oil-based medium-voltage switchgear and the increased risk that they pose.

While the risk of an arc fault still exists in modern medium-voltage switchgear, both the likelihood and the damage it can cause are greatly reduced thanks to arc fault tested designs in compliance with IEC 62271.200 and other measures.

However, the arc fault safety rating of type-tested stand-alone switchgear can be easily negated by incorrect installation that doesn’t properly consider arc ducting, venting and expansion volume requirements.

“In practice, installation contractors or switchroom builders are not always fully aware of or understand these requirements, or in some cases it may be too technically difficult to achieve,” said NHP’s Medium Voltage Product Manager, Dmitry Lazarchuk.

“In many cases the complete substation or kiosk solution needs to be arc fault tested to prove it still maintains arc safety ratings of the switchgear. Therefore, the ideal switchgear would have to fully contain the internal arc fault so that arc venting is no longer required,” said Mr Lazarchuk.

A short-circuit or another malfunction can create an internal arc and when this occurs in a medium voltage cubicle, it can severely damage the installation and possibly injure the operator.

NHP Medium Voltage Switchgear cubicles are designed and type-tested to mitigate the consequences of internal arcs, and therefore protect both the operator and the installation. Through a strategic pressure release system, the internal arc is restricted to the compartment where it originated and it does not spread towards the operator or to other compartments.

The cubicles are specifically designed to minimise the consequences of an internal arc and forming a key component of this is the option of a built-in arc quenching system, “Arc Killer”, which can extinguish an arc in less than 50ms.

Exclusive to NHP switchgear, Arc Killer is a unique worldwide patented system developed in Europe for the DF2 series air- insulated modular type switchgear.

It provides an efficient and also simple arc fault protection, not only for switchgear in substations, but also in the ring network without the need to send a remote trip signal to upstream CB, unlike typical systems based on arc flash relay.

“Arc Killer from NHP protects medium-voltage switchgear from internal arc damage and allows fast restoration of switchgear, avoiding long downtime and huge financial loss.

“It also ensures the highest level of operator safety in the unlikely event of an internal arc fault, going beyond requirements of the Australian standards,” said Mr Lazarchuk.

Arc Killer takes arc quenching to a new level, providing improved security that protects valuable switchgear and eliminating blast damage to switchrooms caused by expanding gas high pressures and temperature generated by arc faults.

Not only are the operator and the environment shielded from harm, but the super-swift arc extinguishing system allows cubicles to be back in operation very quickly in case of an internal fault.

Moreover, Arc Killer’s fast operation allows full containment of the arc fault within switchgear enclosure without the need for external ducting or venting. Consequently the substation design is simplified and the arc fault safety rating of switchgear is always maintained irrespective of where and how it is installed.

The Arc Killer technology and the benefits that it brings to a site highlights the advantage of partnering with a medium-voltage supplier such as NHP.

In additional to the market leading range of switchgear complete with Arc Killer technology, the extended NHP medium-voltage range can be called upon to help users leverage information to improve their operations, network efficiency and ultimate reliability.

For the successful monitoring, evaluation and intelligent control of a distribution substation, as well as substation control systems architecture, NHP is your trusted partner.

This partner content is brought to you by NHP. For more information, visit

Lauren brings a fresh approach to content. While she’s previously written for publications as diverse as Australian Geographic, The Border Watch and Girlfriend, she’s found her true passion in her current role as an editor in the world of energy and infrastructure trade magazines.

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