http___www.informatika.buzdo.com_s215-besprekidno-napajanje-ups.htm_1.xml
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Pulse rectifier (SPS - Switching Power Supply) computers can somewhat mitigate voltage instability metropolitan network, but in terms of a power outage or severe power surges - 'syringe' is of no use. In the event of a power line voltage off the computer because its adapter no possibility of accumulation of energy and inevitably leads to loss of current information in working memory, or worse can damage the tracks on the disk drive if the recess formed in the moment of reading or writing disk. No idyllic scenario for one server. To safeguard the validity of the computer, and thus the data stored on the disks when working with a computer, it is useful to connect to a computer via the source uninterruptible power supply - UPS (Uninterruptable Power Supply). In the event of a power failure using internal battery ensures your computer, the line voltage for a few minutes to a few tens of minutes, depending on the consumption of a computer system and the battery capacity, which is enough to store data and shut down in the meantime, there is no establishment of the line voltage. UPS I realized as switching (off-line) which reacts exclusively by a power failure when in a few thousandths of a second generation of electronics over network voltage conversion of battery voltage or a constant (on-line) that continuously performs conversion of battery voltage to AC voltage and the battery are constantly being updated. Of course, the other species exposed to continuous stress and therefore larger and heavier and more expensive. Good properties have UPS devices like 'off-line' holding voltage stabilizer (AVR - Automatic Voltage Regulator) which reduces the line voltage fluctuation, even in the range of 150 V-300 V (European standard). For UPS is important and the time needed to 'understand' disappearance of the line voltage and generating power from its own DC/AC (direct current / alternate current) converters, and response time (response time / switching time) if power voltage is good that the 'off-line' device is less than 5 ms. Importance forms generated output voltage is also of importance, and it may be a rectangular shape, or some variant of the closest form of sinusoidal or sinusoidal form, which of course raises the price of the device. No matter what type of UPS is selected, it is good to opt for one that has a 25%-50% greater opportunities for effective power control and the burden is not advisable to use consumers who have inductive properties. What is the battery capacity greater autonomy for individual work is higher, which is useful for servers that are essentially the day without physical inspection. If the line voltage fluctuates too much attention should be paid to the range of fluctuations in line voltage that the UPS can cancel Then this particular character is more important than the capacity of the battery installed. The purpose of the decision when purchasing the device shall first determine what are the common phenomenon on the power supply line that is used to connect the computer. Better UPS devices (usually branded SMART) have a serial port (COM) or USB port for connection to a computer, which along with related program support monitors the condition Consuming batteries if power fails. When the battery voltage reaches below a critical threshold, the UPS signals that the computer automatically shuts down, and then automatically UPS is turned off. Understandable optical and acoustic signaling UPS is not superfluous. Example XVI Principle of working UPS 'off-line' type. In the presence of the line voltage switch 'P' stands in the position of '1', and the battery is charging power through an AC adapter. In the event of a power line voltage, the control electronics for a few thousandths of a second facility electrical power failure and switches the switch to position '2' and uses AC voltage 220 V (Europe) obtained from the inverter battery voltage. By establishing the line voltage control electronics switches switch 'P' in position '1'. The stabilizer is a circuit that not all UPS devices. Has the task to automatically adjust the line voltage at the rated value of 220 V in the case of deviations to less or greater value than the standard, which uses auto transformer (line-interactive UPS). The filter has a duty to mitigate distortion forms the output voltage, which is the value of 25-30% reduces the value of approximately 5-10% (liabilities PFC). If on the other hand uses an advanced electronic system that acts as an active filter (Active PFC) distortion is about 5% at any load. In doing so, the vectors of current and voltage phase trying to get closer to reactive power can be limited. Using IGBT (insulated gate bipolar transistor) technology distortion can be reduced by up to 2%. UPS type 'on-line' no branch that leads to the switch position '1 'and continuously performs correction and conversion of electrical energy (double-conversion). The advantage is that consumers are then continuously separated from the line voltage, which contributes to the security and stability of the system. Certainly PFC system is implied. So, according to the form of the output voltage if power system voltage UPS is made with the converter as a generator of sinusoidal output voltage or rectangular shapes. Sine wave generator is more useful because it enables the connection of inductive loads, but its price is higher. For the server is certainly good to choose exactly this type of UPS, and opportunities to Croatia to choose such an energy capacity of the battery to ensure the autonomy of the system for at least 12 hours.
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Impulsni ispravljač (SPS - Switching Power Supply) računala donekle može ublažiti nestabilnosti gradskog napona mreže, ali u pogledu nestanka struje ili jakih naponskih udara - 'špriceva' nije od koristi. U slučaju nestanka napona gradske mreže računalo se isključuje jer njegov ispravljač nema mogućnost akumuliranja energije i neminovno dolazi do gubitka tekućih podataka u radnoj memoriji, ili što je još gore može doći do oštećenja zapisa na samome disku ako je prekid nastao u momentu čitanja ili pisanja s diska. Nimalo idiličan scenarij za jedan poslužitelj. Glede očuvanja ispravnosti računala, a time i spremljenih podataka na diskovima tijekom rada s računalom, korisno je računalo povezati preko izvora besprekidnog napajanja - UPS (Uninterruptable Power Supply). U slučaju nestanka struje preko ugrađenog akumulatora osigurava računalu napon gradske mreže u trajanju od nekoliko minuta do nekoliko desetaka minuta, ovisno o potrošnji računalnog sustava i kapaciteta akumulatora, što je dostatno za pohranu podataka i isključivanje računala ako u međuvremenu ne dođe do uspostavljanja napona gradske mreže. Sam UPS realizira se kao preklopni (off-line) koji reagira isključivo po nestanku struje kada u nekoliko tisućinki sekunde elektronika preuzima generiranje napona mreže pretvorbom napona akumulatora, ili stalni (on-line) koji neprekidno vrši pretvorbu napona akumulatora u izmjenični napon mreže a akumulator se neprekidno nadopunjava. Naravno, druga vrsta izložena je neprekidnom naprezanju te je gabaritnija i znatno skuplja. Dobra svojstva imaju UPS uređaji tipa 'off-line' koji posjeduju stabilizator napona (AVR - Automatic Voltage Regulator) koji ublažava kolebanje napona gradske mreže, čak u rasponu od 150 V - 300 V. Za UPS je važno i vrijeme potrebno da 'shvati' nestanaka napona gradske mreže i generiranja napona iz vlastitog DC/AC (direct current / alternate current) pretvarača, odnosno vrijeme odziva (response time / switching time) po nestanku napona gradske mreže koje kod dobrog 'off-line' uređaja iznosi manje od 5 ms. Važnost oblika generiranog izlaznog napona također je od značaja, te može biti pravokutni oblik ili neka njegova varijanta najbliža sinusnom obliku, ili sinusni oblik što naravno poskupljuje uređaj. Bez obzira koja se vrsta UPS uređaja odabere, dobro je odlučiti se za onaj koji ima 25%-50% veće mogućnosti po snazi od snage tereta kojeg nadzire i nije preporučljivo koristiti potrošače koji imaju induktivna svojstva. Što je kapacitet akumulatora veću autonomnost samostalnog rada je veća, što je korisno za poslužitelje koji su u suštini tijekom dana bez fizičkog nadzora. Ako napon gradske mreže previše oscilira pažnju treba obratiti na raspon kolebanja napona gradske mreže koji UPS može anulirati Tada je ova osobitost važnija od kapaciteta ugrađenih akumulatora. U svrhu odluke pri nabavi uređaja prethodno treba utvrditi kakve su uobičajene pojave na napojnom vodu koji se koristi za priključivanje računala. Bolji UPS uređaji (obično nose oznaku SMART) imaju serijski priključak (COM) ili USB priključak za vezu s računalom, čime se uz pripadnu programsku potporu prati stanje potrošenosti akumulatora po nestanku struje. Kada napon akumulatora dođe ispod kritične granice, UPS to signalizira računalu koje se automatski gasi, a potom se gasi sam UPS. Razumljiva optička i zvučna signalizacija UPS-a nije na odmet. Primjer XVI Načelo rada UPS uređaja tipa 'off-line'. Pri prisutnosti napona gradske mreže preklopnik 'P' stoji u položaju '1', a akumulator se puni energijom preko ispravljača. U slučaju nestanka napona gradske mreže, kontrolna elektronika za nekoliko tisućinki sekunde ustanovi nestanak električne energije i prebacuje preklopnik u položaj '2' te se koristi izmjenični napon 220 V dobiven od pretvarača napona akumulatora. Po uspostavi napona gradske mreže kontrolna elektronika prebacuje prekidač 'P' u položaj '1'. Stabilizator je sklop kojeg nemaju svi UPS uređaji. Ima zadaću da automatski podešava napon gradske mreže na deklariranu vrijednost od 220 V u slučaju da dođe do odstupanja na manje ili veće vrijednosti od standardne, pri čemu se koristi autotransformator (line-interactive UPS). Filtar ima zadaću da ublaži izobličenja oblika izlaznog napona, koje se sa vrijednosti 25-30% smanjuje na vrijednost od približno 5-10% (pasive PFC). Ako se pak koristi napredan elektronički sustav koji djeluje kao aktivni filtar (active PFC) izobličenje je oko 5% pri bilo kojem opterećenju. Pri tome se vektori struje i napona nastoje fazno što više približiti kako bi jalova snaga bila što manja. Uporabom IGBT (insulated gate bipolar transistor) tehnologije izobličenje se može smanjiti i do 2%. UPS tipa 'on-line' nema granu koja vodi na položaj preklopnika '1' te se neprekidno vrši ispravljanje i pretvaranje električne energije (double-conversion). Prednost je što su potrošači tada neprekidno odvojeni od napona gradske mreže, što pridonosi sigurnosti i stabilnosti rada sustava. Dakako PFC sustav se podrazumijeva. Dakle, prema obliku izlaznog napona po nestanku napona mreže UPS se izrađuje s pretvaračem kao generatorom sinusnog ili pravokutnog izlaznog naponskog oblika. Sinusni generator je uporabljiviji jer omogućava i priključivanje induktivnih tereta, ali mu je cijena veća. Za poslužitelj svakako je dobro izabrati upravo ovakav tip UPS-a, i za naše prilike odabrati takav kapacitet akumulatora koji će osigurati autonomiju sustava barem 12 sati.