Getting the best from your power
The extensive use of electrical products in today’s society means that protection against the effects of voltage surges is no longer an option, but has become a necessity. In addition, power protection is vital to ensure that not only are losses reduced, but organisations are making the most of their energy. Tom France from Schneider Electric looks at the threats to power quality, the solutions that are available and the benefits of using them.
As business operations become increasingly sophisticated, the use of technologies such as LCD screens, computer networks and data servers, means that protection against voltage surges is crucial. This is also true in an industrial setting, as more advanced solutions are being utilised, such as programmable logic controllers, and production could be set back if power was lost. In addition, surge and lightning protection are essential to any electrical installation in order to safeguard those working within a building. However, despite being a critical part of any installation for all of these reasons, it is not a mandatory requirement under the wiring regulations. However, protection of this kind should always be a consideration when specifying and installing.
So why do voltage surges occur? There are a number of reasons, all of which cause disruption to electrical installations and loads. These are operating surges; transient overvoltage at industrial frequency; those caused by electrostatic discharge; and atmospheric surges. Rises due to atmospheric conditions are caused by lightning, which can result in high levels of damage. Every year the earth is struck by approximately three billion bolts of lightning, potentially causing fires, which can seriously damage buildings and equipment. The cost to any business is not only that of the repair itself but also lost minutes can have significant consequences for any organisation.
To protect against this happening, a risk assessment needs to be carried out to ensure surge protectors are fitted where necessary. A surge protection device (SPD) is a component of the electrical installation protection system. It is typically connected to power cables entering and leaving the building at the main switchboard. However, depending on the design of the electrical scheme, SPDs can also be positioned elsewhere. For example, if the business has air conditioning units on the roof, then it will be vital to include a protection device on the cables to or from the units.
SPDs are designed to limit transient overvoltages caused by lightning, diverting them to earth to avoid causing damage. However, as they are not a focus of the wiring regulations, there may be some confusion about the different types of device available, particularly as electrical designers have not legally had to consider them in any depth.
It is important to recognise that there are three different types available. ‘Type 1’ as part of the lightning protection system protects an electrical installation from the effects of a direct lightning strike to the building or overhead power lines, while ‘Type 2 and 3’ safeguard electrical equipment from the indirect effects of lightning and overvoltages produced from within the electrical system. This can include storms that are some distance away, but still have the potential to damage a power line and consequently affect electricity supplies.
In order to specify the correct protection device for an individual building, a co-ordinated approach and selection process needs to be adopted to address the individual needs of the project. The first step is to estimate the value of the equipment that needs to be protected – not only in relation to its cost, but also economic impact if it fails. This will inevitably include building equipment such as automated heating and air conditioning, as well as lifts, and professional items including computers and servers.
The second stage in the specification process is to identify the electrical architecture of the building or buildings. Dependant on the size of the premises and the extent of its electrical system, more than one surge protector may be required.
Finally designers will need to take into account the risk of the impact of lightning on the site. An urban, low-lying area will be at little risk, whereas a particular hazard such as a pylon, a tree or high structure, will naturally face a greater threat.
By looking at these three different aspects of an installation, a contractor can ensure the right type and number of protection devices can be selected. For example, premises with an automated HVAC system, using a main switchboard and in an area vulnerable to lighting strikes, would require a ‘Type 1’ protection device. A building containing professional equipment such as computers, running from a single switchboard, in a low risk area, would be best protected with a ‘Type 2 or 3’ device.
Many manufacturers of surge protectors, including Schneider Electric, not only supply the devices but are able to assist in specification for those who are not confident in selection the best solution for the project. Designers can also get advice on using surge protectors as part of whole solution, rather than just being viewed as an afterthought. In addition, manufacturers have introduced solutions combining Type 1 and 2 for full protection, and can provide full information on the correct overcurrent protection device needed for the SPD.
An added advantage of surge protection devices is that they are relatively simple to install and retrofit. This means any building can benefit from increased levels of protection, potentially saving extensive refurbishment costs should the worst happen.
Surge protection devices aren’t the only technology that can combat threats to power quality. A key solution that is worth considering is power factor correction, which not only protects power supplies, but also delivers significant cost savings with an excellent return on investment. Active Harmonic Filters (AHF) is the simplest and most effective method to mitigate harmonics, reduce process-related voltage fluctuations, and improve equipment operating life and system capacity.
Power Factor Correction (PFC) also ensures the quality of supply as well as delivering substantial benefits. The quantity of electric motors, induction heaters and fluorescent lighting installed in today’s buildings has significantly increased in recent years. These technologies have clear benefits, but do reduce the power factor and the efficiency of the power supply. Using PFC lowers the current drawn from the electricity supply, decreasing reactive power charging, consumption and CO2 emissions, subsequently creating a greater supply capacity through more efficient energy use.
Surge protection devices and Power Factor Correction are two classic examples of how even though something isn’t mandatory, it is still a vital part of an electrical installation. It is possible that future legislation may recognise the importance of these two types of power protection – particularly from a health and safety point of view for surge protection, and an energy efficiency angle for PFC. However, before this happens they should both be a high priority to consider and ensure the right protection is specified dependent on the individual aspects of each project. This will safeguard businesses and organisations against lost and wasted energy, damage to property and lost minutes, providing peace of mind and an electrical infrastructure that works as hard as possible.
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