10 May 2019
Some 35 per cent of all surges are caused by lightning strikes, utility grid switching or heavy motor loads from nearby industry or even electrical accidents.
The remaining 65 per cent majority are therefore generated within our homes or work places. To provide protection against such events the recently published 18th edition of the Wiring Regulations (BS 7671) has stipulated that surge protection shall be provided on circuits in commercial and industrial installations. Consequently installing Surge Protection Devices (SPDs) in areas such as data centres has now become mandatory even if it has been the common practice.
However, fitting SPDs in the subdistribution board or even relying on those within the UPS is not necessarily job done. Surges can be introduced into the circuits by any number of small motors or switching devices or, as the standard acknowledges, if the physical distance from the SPD is greater than 10m, oscillations can lead to a voltage of up to twice the SPD’s voltage protection level. What data centre doesn’t have 10m of cable run from the nearest SPD?
The standard continues, ”consideration shall be given to the provision of additional coordinated SPDs, closer to the equipment, or the selection of SPDs with a lower voltage protection level”.
Therefore, a more localised type 3 protection perhaps supplied within the rack mounted Power Distribution Unit (PDU) is therefore required if damage is to be avoided to all our electronic based A.V. products, modems and other network equipment.
Any increase in the voltage above the equipment’s normal operating voltage can cause damage to electronic components or printed circuit boards contained within it. Repeated, albeit, smaller surges can ultimately cause the integrity of these parts to breakdown and the first signs you may have is that your printer/scanner, PC or worse still the server stops working.
Spikes and surges are not the only risk unfortunately that needs to be considered if an appropriate level of protection is to be provided. Electromagnetic interference (EMI) is sometimes caused by environmental conditions such as electrical storms and solar radiation but more commonly it is emitted from another electrical device or within the electrical system. It is therefore often necessary to fit an EMI filter to screen out the interference often emitted from electronic power supplies as they convert input voltage to DC at high frequencies; such as from LED lighting, computers, motor drives and battery chargers.
Surge and filter protection does cost and whilst it may be passively doing its job, it’s hard to justify the initial investment. As with any insurance cover however, you may be glad to have it as failure to protect may cost far more!