17-04-2012, 10:29 PM
need a mini project report on mini ups system
do mail me a project report on mini ups system
17-04-2012, 10:29 PM
need a mini project report on mini ups system do mail me a project report on mini ups system
18-04-2012, 10:02 AM
to get information about the topic "ups system" full report refer the link bellow https://seminarproject.net/Thread-mini-u...tem--18105
03-06-2012, 02:35 PM
i need mini project on mini ups system
iam a final year student i nedd full report on mini ups system design that is in case of power failure the light glows
20-10-2012, 03:34 PM
MINI UPS SYSTEM
Mini UPS System (21).docx (Size: 5.29 MB / Downloads: 336) ABSTRACT The circuit being implemented is the “MINI UPS SYSTEM” which is useful for domestic, commercial, as well as industrial application. The aim of our project is to make a system where the battery will be charged using a rectified voltage from an AC source; this battery will take the load instantaneously when the main line power interruption will occur.Using rectification circuit ac-dc conversion is taking place. This circuit provides an uninterrupted power supply (UPS) to operate 12V, 9V and 5V DC-powered instruments at up to 1A current. The backup battery takes up the load without spikes or delay when the mains power gets interrupted. It can also be used as a workbench power supply that provides 12V, 9V and 5V operating voltages. The circuit immediately disconnects the load when the battery voltage reduces to 10.5V to prevent deep discharge of the battery. LED1 indication is provided to show the full charge voltage level of the battery. Miniature white LEDs (LED2 and LED3) are used as emergency lamps during power failure at night. INTRODUCTION An uninterruptible power supply, also uninterruptible power source, UPS or battery backup is an electrical apparatus that provides emergency power to a load when the input power source, typically the utility mains, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide instantaneous or near-instantaneous protection from input power interruptions by means of one or more attached batteries and associated electronic circuitry. The on-battery runtime of most uninterruptible power sources is relatively short—5–15 minutes being typical for smaller units—but sufficient to allow time to bring an auxiliary power source on line, or to properly shut down the protected equipment. While not limited to protecting any particular type of equipment, a UPS is typically used to protect computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption and/or data loss. UPS units range in size from units designed to protect a single computer without a video monitor (around 200 VA rating) to large units powering entire data centers, buildings, or even cities. CIRCUIT DESCRIPTION RECTIFIER CIRCUITS The electronic devices such as transistors and integrated circuits generally require DC electrical power for their operation. This means that before most electronic devices, AC power must be changed or converted into DC power. This process is commonly called rectification. Alternating current differs from Direct current due to the direction of electron flow. In AC, electrons flow first in one direction for a short time. Center tap transformer The center tapped transformers is used here to step down the voltage supply of 230v AC into a 12-0-12v DC voltage source to feed the circuit. A center tapped rectifier is used for this purpose. In electronics, a center tap is a connection made to a point half way along a winding of a transformer or inductor, or along the element of a resistor a potentiometer. This permit the transformation of the amplitude of alternating current (AC) voltages for the purpose of power conversion. One of the major applications of the center tap transformer is rectification using diodes circuits .The working of the combined effect of the diodes and the transformer are explained next. Capacitive Filter This is the most simple form of the filter circuit and in this arrangement a high value capacitor C is placed directly across the output terminals in order to reduce the ripple components in the DC output of the filter. During the conduction period it gets charged and stores up energy to it during non-conduction period. But the discharging time is quite large (roughly 100 times more than the charging time depending upon the value of R) because it discharges through load resistance R.Large the value of capacitor C more it offers a low impedance shunt path to the ac components or ripples but offers high impedance to the dc component. Thus ripples get bypassed through capacitor C and only dc component flows through the load resistance R.. VOLTAGE LEVEL INDICATOR CIRCUIT Main part of this circuit is the NPN general purpose amplifier BC548. A standard step down transformer provides 12V of AC, which is rectified by diodes D1 and D2. Capacitor C1 provides ripple-free DC to charge the battery and to the remaining circuit. When the mains power is on, diode D3 gets forward biased to charge the battery. Resistor R1 limits the charging current. Potentiometer VR1 (10k) with transistor T1 acts as the voltage comparator to indicate the voltage level. VR1 is so adjusted that LED1 is in the ‘off’ mode. When the battery is fully charged, LED1 glows indicating a full voltage level of 12V. SWITCHING AND REGULATOR CIRCUIT Switching is done by a Darlington pair transistor (PNP TIP-127) to prevent the battery from deep discharging. When the battery voltage or input voltage falls below 10.5V, a cut-off circuit is used to prevent deep discharging of the battery. Resistor R3, Zener diode ZD1 (10.5V) and transistor T2 form the cut-off circuit. When the voltage level is above 10.5V, transistor T2 conducts and its base becomes negative (as set by R3, VR2 and ZD1).But when the voltage reduces below 10.5V, the Zener diode stops conduction and the base voltage of transistor T2 becomes positive. It goes into the ‘cut-off’ mode and prevents the current in the output stage. Preset VR2 (22k) adjusts the voltage below 0.6V to make T2 work if the voltage is above 10.5V. DESIGN OF PCB Designing of PCB is a major step in the production of PCB’s.It forms a distinct factor in electronic circuit performance and reliability. The productivity of a PCB, its assembly and serviceability also depends on the design. The designing of PCB consists of designing of the layout followed by the preparation of artwork. The layout should include all the relevant aspects and details of the PCB design, while the artwork preparation brings it to the form required for the production process. Hence a concept clearly defining all the details of the circuit and partly of the equipment is a prerequisite before the actual layout can start. Depending on the accuracy required, the artwork might be produced at 1:1 or 2:1 even 4:1 scale. It is best prepared on a 1:1 scale. Since the layout for our circuits was already available, we did not have to implement these procedures. Layout Approaches First the board outlines and connectors all marked on a sheet of paper followed by sketching of the component outlines with connecting points and the conductor patterns. Prepare the layout as viewed from the component side (top side) first, so as to avoid any confusion. The layout is developed in the direction of signal flow, as far as possible. This reduces the number of interconnections. Among the components the larger ones are placed first and the space in between is filled with smaller ones. Components requiring input/output connections come near the connectors. All the components are placed in such a manner that soldering of other components is not necessary if they have to be replaced. The PCB layout may be divided into functional sub units. Each of these sub units is realized on a definite portion of the board. This improves functional reliability and enables faster testing and servicing of the board. |
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