How smart circuit protection can help provide additional protection for properties

March 2nd 2020

You could be forgiven for thinking that circuit protection devices are not “smart”.

It’s an easy mistake to make when your go-tos are comparatively simple devices like MCBs and RCDs, which have been around for a long time and which are decidedly not smart.

Even though these familiar technologies are appropriately used to help to provide particular levels of safety in electrical installations and to provide protection, for people and property, against the dangers that can arise from certain types of electrical faults, they are limited to that level of protection by the nature of the technology that they use.

However, is that level of safety high enough?

Smarter circuit protection are devices now available.

New devices are in the market that can provide additional levels of protection. AFDDs, (arc fault detection devices) use microprocessors to monitor the condition of electrical circuits and will automatically disconnect any circuits that suffer from a dangerous arc fault thus preventing an electrical fire.

These smart little devices provide higher level of protection than ever before by detecting dangerous faults that older technologies like MCBs and RCDs cannot detect.

Until now designers and installers of electrical installations have not been able to access arc fault detection devices that would fit easily into consumer units.

However, Crabtree have overcome that problem with the Starbreaker single module miniature arc fault detection device (or mini AFDD for short).

Being called ‘mini’ is no comment on the level of protection it provides but simply one of size. Crabtree’s mini AFDD uses the same space as a single MCB but incredibly it includes three technologies, MCB, RCD and AFDD.

This allows designers and installers to integrate AFDDs into any residential installation and comply fully with the requirements and recommendations of the 18th Edition Wiring Regulations. 

The technology behing arc fault detection devices

By using smart digital technology, the SIARC software analyses a wide range of criteria, not only current and voltage, constantly measuring the high frequency (HF noise) to look at the intensity stability and duration and the gaps between noise segments to reliably distinguish between ‘operational sparking”- for example, in washing machines and vacuum cleaner motors - and abnormal activity that could denote a potentially dangerous event. 

The software works by repeatedly making numerous calculations per second. If an arc detection signal does not break all 5 of the detection criteria shown in Fig 1 it will not fit into the orange pentagon “arc fault zone” and the device will not operate.

Only dangerous arcs will be greater than all 5 detection criteria and this leads the AFDD to operate and remove the dangerous arc that could lead to a fire.

These smart devices are suitable for all types of final circuits and will work equally as well on radials and ring circuits, on lightly loaded circuits and on higher load circuits.

Starbreaker Mini AFDDs protect against both serial and parallel arc faults, providing an extra layer of protection against the risks from arcing referred to in the 18th Edition IET Wiring Regulations, while also helping future-proof installations against ever-changing regulations.

Serial arc faults for example, are typically found in loose connections or frayed/damaged/crushed or impacted conductors. Serial arc faults are faults that occur within the current path within a conductor or a loose connection in the circuit. Parallel arc faults occur between conductors like a micro short circuit.

These arcing conditions can cause severe overheating and lead to ignition of cable insulation and surrounding materials.

Whereas parallel arc faults are typically found with damaged or degraded insulation that allows current flow between conductors. These arcing conditions can cause overheating and lead to ignition of cable insulation and surrounding materials.

Parallel arc faults cannot be detected by MCBs, RCDs or RCBOs because the current flow in these conditions will always be less that the operating load current, parallel arc faults are not short circuit faults.

While RCDs and MCBs protect against overcurrent, short circuit and earth leakage protection, they’re unable to detect arcing, leaving a potential gap in the safety provision.

Crabtree’s Starbreaker Mini AFDD

Delivering maximum safety in the minimum footprint and complying fully with the requirements of BS7671, Crabtree’s single module, “mini AFDD” is a two-pole switching device which will totally isolate any faulty circuit or appliance, ensuring complete peace of mind for installers, homeowners and investors.

As an additional benefit, the Crabtree’s Starbreaker Mini AFDD is an easy to fit ‘plug and play’ option that can be installed into any appropriate Starbreaker consumer unit, without the need for special assembly or new busbars.

So, it’s equally suitable for new builds, upgrades and retrofits to provide additional protection.

Bringing three levels of safety in one easy-fit single module, Crabtree’s Starbreaker Mini AFDD represents a major step forward in smarter electrical safety.

For a smarter look at arc fault protection, click here - www.electrium.co.uk/mini-AFDD 

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