Skip to content Skip to footer

Why consider arc protection?

Electrical Review Logo

When power protection is evaluated the need to consider the arc fault events is
often neglected. However, the risk is at a high price when it takes so little to be safe.

Explosion risk and costly downtime is avoided with new easy system.

An arc fault can have numerous causes, but it will always happen due to a breakdown of the isolation between two conductors with a high difference in potential. Switchboards and transformers are designed to have sufficient isolation between their conductors (e.g. by air gap) but this isolation can be degraded by
humidity, salty air (contamination), rodents and insects, someone dropping a tools, poor connections, etc.

Once the arc happens it can, within a few milliseconds, develop into a very powerful explosion that can completely destroy an entire switchboard and injure or kill nearby personnel.

The threat is not considered
Our world is becoming increasingly dependent upon electricity. Applications that were formerly driven by fossil fuels are being replaced by wind turbines, solar cells, and other environmentally friendly power sources. A steady and dependable supply of electricity is crucial, no matter whether the electricity is used for life support systems at hospitals, to keep a ship dynamically positioned beside an offshore platform, or to keep our large scale datacenter on-line 24 x 7 x 365. In these applications a short power outage is costly, while long term downtime of the electricity supply can be an absolute disaster.

In many applications much is done to ensure a stable and continuous supply of power. Production facilities and it-centers invest in back-up battery systems, back-up generators and fire protection systems. Electrical power distribution switchboards within these applications are to some extend protected against failure by overcurrent, short-circuit, etc. Despite these efforts to ensure stability, one important measure is often forgotten – arc protection!

Most people tend to think that their switchboard will be sufficiently protected by e.g. overcurrent and a short-circuit relay. While this may be true for low voltage switchboard with small current, traditional current protection will not be sufficient for medium and high voltage switchboards, which harness larger amounts of energy. The same applies to transformer stations, wind turbines, and diesel electric propulsion systems.

The challenge is all of these applications are under a constant threat from arc flashes, which may happen due to breakdown of the isolation between conducting materials inside the enclosures – e.g. between busbar rails or between transformer primary or secondary phase connections. An arc of an arc fault has the same properties as the arc or a welding process. However, the difference is that the welding equipment is keeping the energy to its arc under control, while the arc fault is typically "let loose" and feed by all the energy available to the application – that is unless the application is very quickly disconnected by an arc protection system.

Affordable plug-and-play solution
The devastation of an entire switchboard, a transformer station, or a wind turbine nacelle can be very costly, not so much because of the damage inflicted, but mainly because the time it would take to rebuild the installation. An arc fault happening on a dynamically positioned vessel placed beside an oil rig could cause the vessel to lose propulsion and result in an environmental catastrophe. A burned-out power distribution switchboard at an IT datacenter could cause prolonged downtime of customer IT systems, which would almost certainly affect customer confidence – and ultimately ruin the business.

Arc protection systems are typically expensive both to buy and operate. Many of these systems have complicated user interfaces for configuration and daily operation and they consist of multiple units that have to be interconnected. With the launch of the new D1000 Arc Protection, Selco has made arc protection easy and affordable. The D1000 consists of a single module supporting up to six optical point or fiber optical sensors. One D1000 will cover an entire switchboard and is more or less a plug-and-play installation.


Top Stories