![]() ![]() In a standby ("off-line") system the load is powered directly by the input power and the backup power circuitry is only invoked when the utility power fails.A line-interactive UPS maintains the inverter in line and redirects the battery's DC current path from the normal charging mode to supplying current when power is lost.An on-line UPS uses a "double conversion" method of accepting AC input, rectifying to DC for passing through the rechargeable battery (or battery strings), then inverting back to 120 V/230 V AC for powering the protected equipment.The three general categories of modern UPS systems are on-line, line-interactive and standby: To prevent this, a UPS should be selected not only by capacity, but also by the quality of power that is required by the equipment that is being supplied. Ī UPS unit may also introduce problems with electric power quality. Some manufacturers of UPS units categorize their products in accordance with the number of power-related problems they address. Harmonic distortion, defined as a departure from the ideal sinusoidal waveform expected on the line.Noise, defined as a high frequency transient or oscillation, usually injected into the line by nearby equipment.Momentary or sustained reduction in input voltage.However, most UPS units are also capable in varying degrees of correcting common utility power problems: The primary role of any UPS is to provide short-term power when the input power source fails. 9.4 Series new/old battery interactions.9.3 Series-parallel battery interactions. ![]() 9.2 Testing of strings of batteries/cells.9.1 Common battery characteristics and load testing.3.1 Hybrid topology/double conversion on demand.The world's largest UPS, the 46-megawatt Battery Energy Storage System (BESS), in Fairbanks, Alaska, powers the entire city and nearby rural communities during outages. UPS units range in size from ones designed to protect a single computer without a video monitor (around 200 volt-ampere rating) to large units powering entire data centers or buildings. It is a type of continual power system.Ī UPS is typically used to protect hardware such as computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. ![]() The on-battery run-time of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries, supercapacitors, or flywheels. A large data-center-scale UPS being installed by electriciansĪn uninterruptible power supply or uninterruptible power source ( UPS) is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails. ![]()
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