Independently from our location and the way our appliances are connected to the power supply network, we should always be concerned about all mains disturbances that might affect our equipment; but we should also be aware of their relative frequency of occurrence and take into consideration the environmental impacts and costs that preventive solutions imply.
Disturbances can be categorized into 17 sub-groups that detail the seven types mentioned by IEEE Standard 1159-1995.
Some of these defects may not occur for years, but others, occurring more frequently, can go up to several times a day. Regarding their effects, as it has been stated previously, some disturbances have little impact on equipment’s functions, comparing to others that might have severe and even fatal consequences for appliances.
Uninterruptible Power Supplies (UPS), especially 2000 VA and above, can generally cover most of the defects that happen repeatedly. In rare cases, eliminating defects can be quite costly: it causes loss of efficiency and environmental pollution, due to considerable waste of energy.
According to a research, conducted by Fotrousi Electronic Research Center during five years, it has been established that out of 16,000 line-interactive UPS, with an average power of 3KVA and 98% efficiency, there have only been 13 unsolved cases that needed to be substituted by equivalent double-conversion UPS, providing only 90% of efficiency.
This means that over 99.9% of existing mains disturbance patterns can be supported by line-interactive UPS.The report continues by stating that in 3 of the 13 cases, instead of being fed by the mains electricity network, the UPS input has continuously been connected to power generators with no output frequency tuning, and the operator was not willing to fix it (Defect #17 of the above-mentioned table).
In the 10 remaining cases, the UPS were exposed to such high fluctuations in the input voltage that there was no time for the batteries to be charged (Defect #15 of the page 4 table). Based on this report, these UPS were estimated to be in average loaded up to 50% of their nominal power. If double-conversion UPS had been used instead of line-interactive ones, more than 16000 MWh of energy (i.e. more than $2,000,000) would have been wasted every year. Besides trying to offer appropriate products for each class of applications, Hyundai Corporation aims to simultaneously reduce electricity problems and improve the efficiency.
Some of Hyundai outstanding points in producing UPS are: 5 Increased safety factors and protection circuits and reduced battery voltage level to SELV (Safety Extra Low Voltage) standard (48 VDC) in Class B and Class E of Hyundai UPS for unstable conditions, unknown and heavy inrush current loads. The average efficiency for these two groups of UPS is more than 98% and the useful lifetime is over than 150,000 hours. Parallel redundant design of internal power parts of both classes, so that any possible problem results in power reduction, instead of damaging the whole unit. Offering the small economic class A UPS for home appliances and single PC. Offering the double-conversion class C UPS up to 20 KVA, made lighter and more economic by eliminating the iron core transformer; suitable for small and middle office purposes in stable electricity network environments. Can be paralleled from 6 KVA and above. Offering advanced double-conversion class D UPS, equipped with output galvanized isolation available up to 120 KVA and capable of being paralleled for more power. Offering “Total Solution UPS Package” with more than 92% efficiency including double-conversion specifications, galvanized isolation at rectifier input, galvanized isolation at inverter output, 48 VDC bus with no booster, THDI less than 7% and input power factor of more than 0.99, separate modules for parallel redundant rectifier SR series and inverter SI series, that can easily be augmented or changed for more power and performance. These special features extend the useful life of the units and enable the customer to design and assemble MC series by-pass control unit, RU series racks and single-and three-phase UPS, based on the customer’s requirements.