Uninterruptible power supply

The main function of this device is to provide uninterrupted power to your computer or other devices during a power outage.

Working Principle

The device provides uninterrupted power from its built-in rechargeable battery. This battery generates a direct current, which the inverter converts into an alternating current of the desired voltage.

The computer connected to the uninterruptible power supply is normally powered by the mains and the battery is charged. If there is a power failure due to a power line failure, the computer is switched over to the uninterruptible power supply battery.

1 - Input power from the mains

2 - Charging unit

3 - Battery

4 - Inverter

5 - Automatic switch

6 - Mains filter

7 - Output power from the device to the equipment

The models of such devices are equipped with a light indication and audible alarm, which notifies you when autonomous operation begins.

The uninterruptible power supply autonomy time depends on the battery capacity level. The battery capacity is indicated in the certificate of the device or the specifications on the website of the official manufacturer of the uninterruptible power supply.  A five-minute run time is considered sufficient for the typical user, enough time for saving documents and shutting down the computer.

Types

Redundant uninterruptible power supply

It is a simple and affordable uninterruptible power supply. Its efficiency is about 60%. The network filtering is partial, which means that surges and interference in the network, which deteriorate the quality of the equipment, partially reach your computer.

Such an uninterruptible power supply is inexpensive and suitable for home use together with a PC.

Line-interactive uninterruptible power supplies

This type of uninterruptible power supply stabilizes the mains voltage using a switching device. If the mains voltage drops by more than 20%, the uninterruptible power supply automatically switches on and supplies power to the computer. The function of the switching device is to ensure that the UPS switches on only when the voltage is completely lost, not when it is reduced. Therefore, the output voltage of this type of uninterruptible power supply is stable. The efficiency is approximately 85%.

Double conversion uninterruptible power supply

This is the most reliable of the reviewed devices. The double-conversion technology provides almost 100% protection for the equipment. The current rectifier converts the incoming current from the mains to the direct current and the inverter converts the current back to alternating current. The batteries are installed between the rectifier and the inverter. Using this battery connection, delays when switching to stand-alone mode are minimized because the use of the inverter requires no additional switching.