Uninterruptible power supplies are among the most popular backup power sources available today. One key defining characteristic of UPS systems is that connected devices are not shut down even when the changeover to the UPS is in progress. Unlike generators, there is no interruption as far as the user is concerned, and this is why they are labelled as uninterruptible.
All it needs is a storage battery and an inverter to convert DC to AC. The battery charges itself when the grid is functioning normally. If the grid voltage falls below a predefined level, the backup kicks in and starts powering the connected devices instead.
There are three basic types of UPS systems - standby (SPS), Line Interactive, and Online or Double Conversion type. The difference is mostly in how they switch over from the mains to the backup. The standby is the cheapest type, where the device has to switch mechanically from the grid circuit to backup.
While there is a small time period (less than 25 ms) required for the changeover, it is too small to affect devices like computers. The more advanced double-conversion type eliminates even this tiny powerless time gap. That is because the components of the circuit are connected serially in this case.
A rectifier converts the AC grid to DC and sends it to the battery, which is connected to the inverter. The inverter converts it back to AC and powers connected devices. In case the AC grid fails, the battery won't get any input but it still continues sending its output to the inverter.
Uninterruptible power supplies can't be used as generators to keep devices on for a very long time. An ordinary SPS will have utmost 15 to 20 minutes before its charge runs out. But this is more than enough time for users to finish or save their tasks and make sure that devices like computers are shut down properly.
All it needs is a storage battery and an inverter to convert DC to AC. The battery charges itself when the grid is functioning normally. If the grid voltage falls below a predefined level, the backup kicks in and starts powering the connected devices instead.
There are three basic types of UPS systems - standby (SPS), Line Interactive, and Online or Double Conversion type. The difference is mostly in how they switch over from the mains to the backup. The standby is the cheapest type, where the device has to switch mechanically from the grid circuit to backup.
While there is a small time period (less than 25 ms) required for the changeover, it is too small to affect devices like computers. The more advanced double-conversion type eliminates even this tiny powerless time gap. That is because the components of the circuit are connected serially in this case.
A rectifier converts the AC grid to DC and sends it to the battery, which is connected to the inverter. The inverter converts it back to AC and powers connected devices. In case the AC grid fails, the battery won't get any input but it still continues sending its output to the inverter.
Uninterruptible power supplies can't be used as generators to keep devices on for a very long time. An ordinary SPS will have utmost 15 to 20 minutes before its charge runs out. But this is more than enough time for users to finish or save their tasks and make sure that devices like computers are shut down properly.
About the Author:
At the UPS Company we are providers of power protection and service solutions including UPS systems, standby Diesel Generators, power stabilisers, inverters, DC power supply systems, software and other accessories.
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