• • • ENERGY EFFICIENCY • • •
Improving electrical maintenance Why getting the right surge protection is critical
ransient over-voltages caused by lightning can result in the almost immediate and total failure of electrical equipment, requiring expensive repairs and replacements. Like any electrical asset, surge protection devices are vulnerable to voltage surges. Here John Mitchell, Global Sales & Marketing Director at CP Automation, explains why good surge protection is key to effective maintenance regimes. In October 2023, a lightning strike caused a huge explosion at Severn Trent Green Power facility in Oxford. Thankfully, nobody was injured, but it was a stark reminder that lightning can strike at any time, and that electrical systems must be shielded from damage.
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The need for surge protection is clear; a voltage spike typically lasts one to 30 microseconds and can reach over 1,000 volts. Meanwhile, longer-term voltage surges can last for seconds, minutes or even hours. In some cases, this can lead to complete equipment failure, forcing production to stop. Left unattended, transient surges lead to false zero crossing of the sine wave, the instantaneous point at which no voltage is present. Electrical devices can be falsely triggered because of fast changing signals caused by transients. Surge protection devices (SPDs) protect electrical equipment by preventing excess voltage appearing at the terminals. While popular, traditional SPDs, like surge arresters, are limited in the protection they offer.
Over the years, equipment’s processing power has grown and the ability to do more has become increasingly important. The result of this design is that the electronics inside are running on lower voltages internally, making them more vulnerable to transients. Industrial facilities have embraced newer technology, which has revolutionised production information and efficiency through
device-to-device communication, processing speed and storage. Many are now using variable speed drives (VSDs) to control the frequency and voltage supplied to electric motors as one example of process and or efficiency improvements. Although typical SPDs, like surge arresters, have been the default choice of protection, they still allow significant voltage to pass through before failing, called let-through voltage. This can still be catastrophic to the equipment being protected.
Are you really protected? Operators may treat surge protection as a tick-box exercise, installing an SPD but not always monitoring it. Without regular condition monitoring, there could be damaging consequences.
Many traditional SPDs do not account for low- level transient surges, and they almost never have a relay output. Furthermore, once the SPD has blown in response to a transient, the site is no longer protected. Think of it as like blowing a lightbulb fuse, once it’s out, it’s out.
Re-thinking maintenance In many industrial facilities, preventative maintenance schedules centre around production-critical assets, such as the bearings on motors inside conveyer belts. However, this narrow view overlooks the risks to all electrical equipment, which can injure staff and put operations behind schedule.
On top of this, many SPDs are typically housed in control systems in hard-to-find locations and left unattended.
When visiting such a site, we often recommend re-assessing maintenance regimes and adapting them to place greater emphasis on surge protection. Once the maintenance schedule is
updated, operators must work with an experienced partner to source and install the correct surge protection.
Preparation and planning Industrial sites can never be 100 per cent protected against lightning and transient over- voltages, but operators can prepare by installing transient protection systems that can eliminate the effects of low-level switching transient events. SineTamer, for example, is designed to monitor all 360 degrees of the sine wave, meaning it can detect rapid changes in frequency.
Surge protection occurs at two stages; the point at which the voltage passes through the device, and once it has already passed through. Traditional SPDs kick-in once the voltage hits a certain threshold, but the energy has already built up by this point. In contrast, SineTamer reduces the voltage let through by around 90 per cent to shield the device from spikes.
It’s also important to know that your SPD will provide continuous power following a strike. In-line surge protection, which many traditional SPDs use, become non-functional once they blow. However, SineTamer will continue to protect after an incident.
Engineers and operators should start by assessing their current SPD’s capabilities and the protection it offers. Then, they should seek out a reliable power quality specialist that can supply and install a device that offers continued protection.
Surge protection is not a new concept, but, as the amount microprocessor-based technology on the factory floor increases, there’s a greater need to select the right SPD. Reevaluating maintenance regimes and selecting SPDs that run in parallel can help maintain protection if lightning were to strike twice.
44 ELECTRICAL ENGINEERING • FEBRUARY 2025
electricalengineeringmagazine.co.uk
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