Operating systems

Uninterruptible power supply (UPS): Definition, Explanation & Examples

  • 4 min read
  • Updated on Nov 12, 2026

Key points at a glance

What is Uninterruptible power supply (UPS)?

An uninterruptible power supply (UPS) protects electronic devices from power failures. Find out more about UPSs and their benefits!

Uninterruptible power supply (UPS): Definition, Explanation & Examples – here you will find the short definition, the detailed explanation and practical examples at a glance.

What is an uninterruptible power supply (UPS)?

An uninterruptible power supply (UPS) is an indispensable part of a modern IT system. It ensures that critical systems continue to function even in the event of power failures or voltage fluctuations. The UPS not only provides backup power, but also protects the hardware from sudden power losses, surges and other electrical anomalies.

Functions and benefits of a UPS

The main functions of UPS systems are:

  • Power supply: In the event of a power failure, the UPS immediately redirects the power supply so that connected devices can continue to operate without interruption.
  • Voltage regulation: The UPS stabilises the voltage and thus protects the hardware from damage caused by overvoltage or undervoltage.
  • Alarm and monitoring systems: Many modern UPS systems offer functions to monitor the power supply and notify you in the event of a problem.

Types of UPS systems

There are different types of UPS systems that are tailored to different needs:

  • Offline UPS: This provides simple backup power and automatically switches over in the event of a power failure.
  • Online UPS: These devices constantly convert the power so that they provide a constant, regulated current, regardless of input fluctuations.
  • Hybrid UPS: These systems combine the functions of offline and online UPSs to deliver optimum performance.

Why is a UPS important for businesses?

Businesses of all sizes need to be prepared for power outages, as these can cause significant costs. A UPS not only protects the hardware, but also the sensitive data. An unexpected power outage could lead to data loss, which has a negative impact on business continuity. In addition, hardware damage can result in high costs. Companies can minimise these risks with a UPS.

Frequently asked questions about UPS

How long can a UPS supply devices with power?

The runtime of a UPS depends on the capacity of the battery and the power consumption of the connected devices. In general, most models can supply power from a few minutes to several hours.

How do I choose the right UPS?

When selecting a UPS, factors such as the total power of the connected devices, the required runtime during power outages and special requirements such as voltage regulation should be taken into account.

Illustrative example on the topic: Uninterruptible power supply (UPS)

Imagine you run a medium-sized company with a server room that is essential for the operation of your most important applications. One night there is a sudden power outage that causes your servers to shut down. Although you have done everything possible to secure your IT infrastructure, there is only one key vulnerability: no uninterruptible power supply in the server room.

The servers that suddenly go down without power could suffer data loss or even cause hardware damage that could cost thousands of euros to repair. If, on the other hand, a UPS had been installed, it would have switched the power supply in just a few seconds and your servers could have continued to operate in the background. Data loss would have been eliminated in this scenario and your business would not have suffered any potential loss of revenue.

Conclusion

An uninterruptible power supply is an essential element of modern IT infrastructures. It protects companies from financial losses that can result from power outages and fluctuations. Careful selection and regular maintenance of your UPS can make the difference between smooth business operations and significant loss.

Further information

If you would like to find out more about IT infrastructure or specific topics such as cloud computing or cybersecurity, please visit our encyclopaedia page.

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Frequently asked questions about Uninterruptible power supply (UPS)

What are the main functions of an uninterruptible power supply (UPS)?

The main functions of an uninterruptible power supply (UPS) include the immediate rerouting of the power supply in the event of an outage, voltage regulation to prevent hardware damage and the provision of alarm and monitoring systems. These functions ensure that critical systems can be operated stably and safely even during power outages, which is crucial for protecting sensitive data and avoiding financial losses.

How does an uninterruptible power supply (UPS) work in detail?

An uninterruptible power supply (UPS) works by immediately switching to an internal battery in the event of a power failure to supply the connected devices with power. With online UPSs, the current is continuously converted to ensure a stable output voltage. The UPS monitors the power quality and can intervene in the event of voltage anomalies to protect the hardware. This technology ensures that critical systems continue to run without interruption.

What types of uninterruptible power supplies (UPS) are there?

There are three main types of uninterruptible power supplies (UPS): offline, online and hybrid UPS. Offline UPSs provide a simple backup power supply and switch over in the event of a power failure. Online UPSs, on the other hand, convert the current permanently and provide a constant output voltage. Hybrid UPSs combine the advantages of both types to achieve optimum performance. The choice of type depends on the specific requirements and the area of application.

How long can an uninterruptible power supply (UPS) supply devices with power?

The runtime of an uninterruptible power supply (UPS) varies depending on the capacity of the battery and the power consumption of the connected devices. As a rule, UPSs can supply power from a few minutes to several hours. The actual runtime depends on the load that the UPS has to carry. To ensure a suitable runtime, it is important to select the UPS according to the requirements of the connected devices.

Why is an uninterruptible power supply (UPS) important for companies?

An uninterruptible power supply (UPS) is crucial for companies as it protects against the financial impact of power outages. A sudden power outage can lead to data loss, hardware damage and significant operational downtime. The UPS ensures that critical systems continue to function and data remains secure. It also minimises the risk of costly repairs and downtime, which is vital for business continuity.

How do I choose the right uninterruptible power supply (UPS)?

Selecting the right uninterruptible power supply (UPS) requires several factors to be taken into account. These include the overall performance of the connected devices, the required runtime in the event of a power failure and specific requirements such as voltage regulation. It is important to select the UPS according to the individual needs of the organisation to ensure effective protection against power outages and electrical faults.

Sources

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  3. Was ist eine Unterbrechungsfreie Stromversorgung? · datacenter-insider.de
  4. Unterbrechungsfreie Stromversorgung (USV) - IT-Kompass · it-kompass.com
  5. Unterbrechungsfreie Stromversorgung USV - Schneider Electric · se.com
  6. UPS-Marktgröße, Trends und Prognoseanalyse 2026-2035 · researchnester.com
  7. Sicherheit durch unterbrechungsfreie Stromversorgung · compufriend.de
  8. USV-Technologien im Vergleich - elektro.net · elektro.net
  9. USV: Die Beste Lösung für Unterbrechungsfreie Stromversorgung · hth-computer.de
  10. USV-Anlagen - Unterbrechungsfreie stromversorgung - Socomec · socomec.de
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