The back-up power market place is currently being swamped by requests for uninterruptible power supply (UPS) systems, power solutions specialist company Meissner’s director, Graham Beyleveld, says.
“Because of the unpredictable rolling power cuts that the country is currently experiencing, customers are looking for a back-up power system that will maintain power supply to certain missioncritical devices that cannot afford to go down.
“A good example of such a device is a programmable logic controller, which, each time it endures a power outage, has to be reprogrammed, resulting in specialist attention and lost production every time there is a power cut. “This severely affects production, and, consequently, affects revenues,” Beyleveld explains.
He says that customers are starting to use previously unknown and unproven UPS systems for a myriad of new applications too, because UPS systems are seen as both clean and quiet and generally provide a better quality and stability of waveform than most smaller generators. However, Beyleveld cautions that UPS systems were not designed to fulfil some of these roles.
Household appliances draw huge amounts of power and the simple rule of thumb should be that the use of anything with a heating element or an electric motor in it should wait until normal power is restored.
A greater problem manifests itself when nontechnical users expect a UPS to be able to give much longer back-up times than they were originally intended to give. Eskom’s rolling blackouts last, on average, two hours to three hours every alternate day where UPSes were traditionally expected to provide a maximum of half an hour back-up once every two or three months.
“Back-up time is purely a function of battery storage capacity, but batteries have their limitations too,” says Beyleveld.
“The challenge lies in the power demand threshold, where it becomes impractical, in terms of size, to use a UPS without a generator. “The power needed from the UPS to support some really large loads becomes so great that the size and cost of the batteries become prohibitive, and, further, because of their size, the batteries will either take a very long time to recharge or simply cannot be fully recharged by the UPS at all,” Beyleveld comments.
He says that with power failures sometimes occuring two or three times a day, the time between power failures is most often not enough to fully recharge the UPS system’s batteries before the next power failure.
“This means that the UPS user will typically only enjoy half of the required power backup during the second power failure and possibly none during the third. “To aggravate matters, the UPS system’s batteries become damaged, because they are discharged before being properly recharged,” Beyleveld points out.
He says that smaller loads of up to 5 KVA or 10 KVA can realistically rely on a well- designed UPS to provide backup for up to five or six hours but that a combination of UPS and a matched generator should be considered for larger loads that require extra long back-up times.
“For small office or home office and domestic applications, Meissner can supply a 5-kVA UPS system that will give in excess of three hours to five hours backup. “The Meissner UPS is of an industrial design, in that the rectifier/charger is suitably rated and designed to recharge the system’s batteries without stressing or damaging them, provided the system has at least a 10-h to 12-h recharge window. “Damaged or uncharged batteries can’t provide backup,” Beyleveld asserts.
He maintains that customers have to ensure that they buy a decent-quality UPS system that is well supported by capable technical backup.
“If it’s worth taking the precaution, then it’s worth spending money to get a decent solution,” says Beyleveld.
He cautions that a large number of UPS systems are being imported from Eastern countries and are snapped up by unsuspecting customers purely because the price is low and, consequently, attractive.
“There are, however, many different types, different designs and different qualities of UPS systems, resulting in a wide variety of prices, something that customers sometimes do not fully understand,” Beyleveld says.
He explains that a common problem in the market is that customers attempt to marry the wrong type of UPS system with the wrong type of generator, usually, the smaller cheaper types of both, and the consequence is that, owing to technical incompatibilities, they simply do not work properly.
“Not all suppliers know enough about the technical pitfalls of marrying a UPS sys- tem to a generator and quite happily flog the uninitiated any old combination, and when challenged afterwards are either completely dismissive or full of poor excuses,” Beyleveld says.
Customers are also attempting to solve their back-up power needs by buying the cheaper alternative, because the current power crisis came unexpectedly and, as a result, no one budgeted for the expenses related to correct back-up power solutions. As with any other commodity, however, the saying holds true that “you ultimately get what you pay for”, adds Beyleveld.
To cope with demand, Meissner is currently importing additional UPS stocks from Powerware, its UPS supplier, which has factories situated in both Finland and the US.
“Meissner also manufactures its own UPS systems that are particularly suited to our local conditions. “The systems tend to be more industrial in nature, and were originally designed to cope with harsh local conditions, such as temperature variations, lightning strikes and pro- blems such as power spikes and power dips associated with power reticulation over vast distances. “The locally manufactured systems are generally better suited to dealing with these conditions,” Beyleveld says.
Although the imported UPS systems are not as robust, they do have more technologically advanced and unusual features, such as special battery current charging programmes and the ability to be monitored over a wide area network, such as the Internet. By using the imported UPS systems, it is also possible to provide parallel redundancy for those really mission-critical applications where power outages owing to UPS failure are simply out of the question.
“In the end, with UPS systems, it is horses for courses. “The customer will have to look at the application, the suitability of the UPS system, and the environment in which the UPS will be operating, not forgetting the support and main-tenance from the supplier of the UPS, ideally, before making the purchase. “Customers have to realise that by buying substandard equipment, they risk having more down time than before, compounding an already large problem through an unwise choice,” Beyleveld concludes.