A UPS (uninterruptible power supply) is a battery-backed device that keeps connected equipment powered for a short time when mains power fails, and often smooths out voltage dips and spikes. Its main purpose is to give you minutes to save work and shut down safely, not to run a system for hours.
Why it matters
Sudden power loss can corrupt files, damage databases, and in rare cases harm hardware. A UPS covers short outages and switchover gaps. Three common designs exist:
- Standby (offline): switches to the battery when power fails. Cheapest.
- Line-interactive: adds automatic voltage regulation to handle sags and surges without using the battery.
- Online (double conversion): always runs the load from the inverter, giving the cleanest power, at higher cost and heat.
Ratings are given in VA (volt-amperes) and watts. The usable watt figure is lower than the VA figure.
Example
A desktop and monitor drawing 250 W on a UPS with a 600 W rating leaves headroom. Runtime on a small unit at that load may be only several minutes. Many UPS units connect by USB and tell the operating system to shut down automatically when the battery is low.
Common mistakes
- Sizing by VA alone and overloading the watt rating.
- Plugging a laser printer into one, since its surge draw can overload small units.
- Never testing the battery, which usually needs replacing every few years.
Related
Get notified when this term updates
Plus occasional practical tips on uptime and monitoring, nothing else. Unsubscribe anytime.
यह पेज सामान्य जानकारी है, जिसे हमारी संपादकीय टीम ने लिखा है और दस्तावेज़ीकरण बदलने पर अपडेट किया जाता है। सर्वर और प्रदाता अलग-अलग होते हैं, इसलिए बदलाव पहले सुरक्षित तरीके से जाँचें। देखें: संपादकीय नीति और अस्वीकरण.