How Does An Uninterrupted Power Supply Work?

What Does an Uninterrupted Power Supply Protect Against?

A UPS, short for uninterrupted power supply, is a device designed to protect electrical systems from getting damaged or from being disrupted after an unexpected power loss. In essence, UPSs act as backup batteries that step in when the mains power supply develops a problem and help ensure critical systems remain active for long enough to be properly shut down in the event of a disruption, especially used in data centre design

Four major power supply problems can befall an electrical supply system, all of which can be avoided by using an uninterrupted power supply system. They are:

Power Surges

A power surge is when there is a sudden increase in the amount of power flowing through to a system or device and is typically caused by things like lightning strikes. During a power surge, there is a sudden increase in power quickly followed by a drop. It is this turn of events that causes damage to equipment.


This is when the power supplied to a system is higher than the power the system requires and can cause damage and overheating. Unlike with power surges, the power influx is over a prolonged period, affecting the system being supplied with power.


An Undervoltage, also known as a brownout, is what happens when the power being supplied is less than what’s required. The problem could be with the grid or a sudden demand for electricity in some other area. Undervoltage can lead to active data loss and systemwide damage.

Power Outage

A power outage is when the supply of power is completely disrupted for either long or short periods. While there are several reasons why power outages happen, the results in most cases can be severe and range from prolonged system downtimes to severe data loss.

What are the Parts of an Uninterrupted Power Supply?

Uninterrupted power supplies are made up of four main components, which, when working in unison, provide a steady flow of power when unexpected electrical hitches occur. The UPS version or type usually determines the arrangement of these components in a UPS system. The layout of an online double conversion uninterrupted power supply is different from that of an offline one. Nevertheless, both system types consist of the following four primary components.

The Charger

A UPS charger ensures your batteries stay charged up while they wait to get activated. It converts incoming alternating current (AC) to direct current (DC) – electricity flows in this form through most of the system.

The Battery

Batteries are where the power that’s used to power your devices when there is a disruption is stored. In most UPSs, the cells are stored in long strings connected in series for uninterrupted power. The problem with this setup is that if a single battery fails, the whole line fails, which is why UPS users are advised to have their batteries tested frequently. The work of the charger is to ensure that the power in the batteries stays as high as possible.

The Inverter

The inverter is basically the second stage of the double conversion process and is a vital element in turning stored battery power to practical, usable electricity. The inverter used in a UPS is what sets the system apart. For instance, in online uninterrupted power supplies, the inverter is always active and in use for seamless changeovers to the batteries when needed. In offline uninterrupted power supplies, the inverter is dormant; when supply is disrupted, a bypass switch inside the system activates it. Inverters also help ensure that power output is modulated, consistent, and stable.

The Switch

For line-interactive and offline UPSs, the switch gets triggered as soon as power from the mains is disrupted, activating the inverter and flipping over to battery supply. In online UPSs, since power is continually flowing through the inverter, the switch acts as a bypass and is designed to trigger and divert over to another circuit for mains power should the UPS fail.

With these four components working in tandem, an uninterrupted power supply ensures that you continue to have access to power even when there is a sudden disruption in the mains supply.