What Is An Uninterruptible Power Supply (UPS)?

21st June 2025
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A UPS (uninterruptible power supply) is a backup power device that provides support when your equipment suffers voltage drops or a power outage. The UPS automatically switches to battery power, ensuring your equipment continues to operate and preventing data loss.

Diesel generators provide vital support for residential, commercial, and industrial operations. They work by offering prime or standby power in remote locations without electricity or during a power outage and are known for their durability and reliability.

Areas that experience regular outages or unstable grids can pair their diesel generator with a UPS, ensuring ongoing power. The combination provides vital protection for sensitive electrical equipment while reducing downtime and ensuring essential services can continue.

Investing in a UPS for your generator can prevent operational downtime and maintain productivity. The UPS stores energy in its internal batteries, which means you can benefit from instant electricity for critical systems while the generator switches on and powers up.

How Does a UPS work?

UPS systems work by providing immediate power support during outages, but they also regulate voltage to protect sensitive equipment. By storing energy in internal batteries, UPS systems power connected devices even when you lose access to mains power.

Normal operation

When you can access mains power, the UPS will take a background role, ensuring its internal batteries are continuously charged.

Online UPS systems undergo a double conversion process: They change AC to DC, which charges the battery, and then convert it back to AC, ensuring your equipment is powered.

Power failure

If a power cut occurs, the UPS will instantly switch to battery power and ensure your devices keep running. In most cases, this switch happens within two to ten milliseconds.

UPS systems typically have a short backup time, but it’s enough for the diesel generator to power up or for your systems to shut down safely.

Power restoration

When your power returns, the UPS will revert to its main function and recharge the battery. It also ensures your connected devices continue to benefit from stable power, reducing fluctuations and offering surge protection.

Key terms:

  • Rectifier: The rectifier converts the AC input power into DC, allowing the system to charge the batteries.
  • Inverter: Once the inverter transforms DC power back into AC, it can provide incoming utility power for your devices.
  • Battery: The battery is a critical component of the UPS system, providing temporary power when you experience a mains failure.
  • Static Bypass: While incredibly rare, the static bypass feature activates if the UPS malfunctions, which routes power from the mains and reduces downtime.

What Are The Different Types Of UPS Systems?

There are three main types of UPS systems, each supporting different applications. Understanding the differences is essential, as choosing the right UPS ensures reliable power.

Offline/Standby UPS

A standby or offline UPS system is the most basic option, but it offers a range of benefits for homes and offices. It works by automatically activating when a voltage drop or power cut occurs, switching to battery backup power in milliseconds.

Investing in a standby UPS can save money and ensure you don’t lose critical systems during an outage if you have small office equipment or a home computer.

Line-Interactive UPS

If you’re looking for ongoing support, live-interactive UPS systems can protect against voltage fluctuations.

An (AVR) automatic voltage regulator will adjust voltages without needing to switch to battery power, making it a valuable investment for offices, servers, and network equipment that require consistent power.

Online/Double Conversion UPS

An online or double conversion UPS is the most advanced option, as it offers continuous power through AC/DC conversion. If you need backup power for a hospital, data centre, or any other environment where even a small amount of downtime can be damaging, these systems are wise investments.

The Benefits of UPS Systems

While UPS systems are an investment, many would agree that they’re well worth it, thanks to each system’s benefits. These benefits include long-term protection, preventing operational downtime and ensuring safety when operating powerful equipment.

Protection from power loss

An Online UPS (uninterruptible power supply) is connected in line with your server and protects your IT equipment and systems when power is lost. In the unfortunate event of a mains failure, the UPS will automatically transfer your equipment to its internal or external batteries until power is restored.

Time to take care of your business

Your UPS will backup your servers for a period of time, allowing other protective actions to take place, such as saving work or making essential communications, before power is lost.

Sometimes, a UPS is combined with a standby generator, keeping your systems online while the generator starts and transfers power to your building.

Protection from power surges

A line-interactive UPS will monitor the quality of your mains power and automatically transfer your load onto batteries if surges or irregularities occur. This protects your servers from damage caused by the main supply.

Things to Consider When Choosing the Right UPS

When investing in a UPS, choosing the right option for your needs is essential. Here are the key factors you should consider:

  • Power Requirements: Calculate the total power consumption of the devices your UPS will support using VA or watts. Choosing a higher capacity model is important, as this ensures the system can accommodate future use and prevents costly upgrades.
  • Type of UPS: When choosing between UPS systems, think about how important your systems are and whether even a few seconds of downtime can cause lasting damage. Understanding this is integral to picking the right option. For example, a basic system is fine for home use, but data centres and settings that rely on emergency equipment should invest in an advanced model.
  • Battery Runtime: How long do your devices need to stay on during an outage? Some UPS systems provide a few minutes of backup, while others provide longer support. However, you can mitigate short runtimes by combining a UPS with a diesel generator.
  • Number and Type of Outlets: Make sure your chosen UPS has sufficient outlets for all your devices, and assess whether it offers data line protection.
  • Form Factor and Space: UPS systems are available in different styles, including compact models, rack-mounted, and tower models. Make sure the one you choose fits your space and infrastructure.
  • Monitoring and Management: Opting for an advanced UPS system gives you features like software integration and remote monitoring, while basic models are less feature-orientated and focus more on functionality.
  • Budget: Basic UPS models are more affordable but can be more expensive in the long term, as you may need to replace them more frequently.

How to Maintain a UPS System

Keeping your UPS healthy ensures your business is, too. By practising regular maintenance, you can benefit from peace of mind and avoid expensive repairs. We recommend following these best practices:

  1. Visual Inspections: Visual inspections are key to ensuring ongoing power protection. Look at the UPS for any signs of damage, including loose cables, dust, and blockages.
  2. Test the Batteries: Batteries are the core of your system, and failing to test them regularly can result in a UPS failure. Most batteries require replacements every three to five years.
  3. Load Levels: It’s vital to avoid overloading the system, and we recommend operating it below its maximum capacity. The sweet spot is around 70% to 80% of the total capacity.
  4. Updates: The manufacturer releases regular updates, which are important to install. Updated systems run more efficiently and are less vulnerable to malfunctions.
  5. Check Logs: Advanced UPS systems offer remote monitoring and event logging. Check these logs regularly to see if your system is experiencing any vulnerabilities.
  6. Clean the Unit: It’s also vital to clean the unit regularly, using an anti-static cloth. Always turn the system off before cleaning it, and avoid using liquids.

How Solent Power Can Help With UPS Systems

We provide complete uninterruptible power supply service. At Solent Power, we specialise in keeping your home or business running. Whether you’re looking for a new UPS system for your diesel generator or need help determining the best support for your current setup, our specialists can help.

As an authorised distributor, we refuse to compromise on quality and offer reputable brands like AEG UPS.

CONTACT US TODAY TO DISCUSS YOUR OPTIONS

FAQs

How can Solent Power help me maintain my UPS System?

We offer an extensive range of UPS (uninterruptible power supply) systems to serve our customers’ needs. We supply various brands of UPS to suit your requirements and budgets.

Our qualified and experienced electrical engineers can also install your new UPS (uninterruptible power supply), and you can trust that Solent Power will ensure your system is safe and compliant.

We offer site power surveys nationwide to help you understand your UPS requirements and help you with what size UPS you need.

As authorised distributors for leading UPS brands such as AEG UPS, we have the trust and support of UPS manufacturers to provide outstanding service for you!

How long will UPS last?

The duration that your UPS will provide power is known as its ‘UPS automation’. Your UPS’s automation depends on factors such as battery capacity, load size, and power factor. Other considerations that affect how long your UPS will last include battery age and condition, operating temperatures, and efficiency.

Where is a UPS system used?

A UPS system is common in commercial applications, providing battery backup and power supplies for computers and IT systems.

Smaller devices or entry-level units can simply plug into the outlets in your building and have their own protected outlets on the rear of the unit. These types of units are readily available for purchase in stock in the UK.

If more power or a larger capacity unit is required, this will usually be fulfilled with an industrial three-phase UPS system. These are common for businesses with larger output requirements and large amounts of data and systems to protect, such as data centres.

What size UPS do I need?

Your UPS system size or power capacity is rated in kVA and is calculated by determining the maximum load of all the equipment and services needed to power your UPS output.

Always factor in the power factor of your UPS device and loads to allow for losses. You will almost always need to oversize to accommodate this. Contact us for advice or to book a site survey.

Paul Phelps Solar Power Owner
Paul Phelps
Paul is the MD of Solent Power and specialises in emergency power solutions, helping to protect your facilities from power loss. Get in touch with us today to discuss the different power brands that we can offer and how they can suit your needs.
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