Frequently Asked Questions (FAQ)

A UPS system, or  Uninterruptible Power Supply, provides an immediate source of backup power if the mains electricity supply fails. This allows connected equipment to continue operating without interruption, helping to prevent unexpected shutdowns, loss of data, disruption to essential services and potential damage to sensitive equipment.

A UPS also protects against poor power quality during normal operation. Depending on the type of UPS selected, it can regulate the incoming supply and protect connected equipment from common electrical disturbances such as voltage sags, surges, spikes, fluctuations and electrical interference.

For shorter power interruptions, the UPS may provide sufficient runtime for the mains supply to recover. During a prolonged outage, it can provide valuable time for equipment to be shut down safely or for a standby generator to start and assume the load. For organisations that rely on critical systems, a UPS is therefore an essential part of maintaining operational continuity and protecting valuable equipment.

UPS systems are available in three main technologies: offline, line-interactive and online. The most suitable option will depend on the sensitivity of your equipment and the level of power protection required.

An offline UPS provides basic protection and remains in standby until a power failure or significant voltage disturbance occurs. A line-interactive UPS offers improved protection by regulating fluctuations in the incoming supply and switching to battery power when required.

An online UPS provides the highest level of protection for critical equipment. It continuously converts the incoming AC supply to DC and then back to AC, producing a clean, stable output that is isolated from common power disturbances and electrical interference.

A more detailed explanation of each UPS technology, together with suitable product examples, can be found here.

The runtime, or autonomy, provided by a UPS system depends primarily on the connected load and the number and capacity of its batteries.

A small plug-and-play UPS will typically provide several minutes of backup power - often up to around 15 minutes, depending on the load, while larger UPS systems can be configured with additional batteries to provide extended runtime of several hours.

Yes. The batteries installed within a UPS system, or in any additional battery cabinets or packs connected to it, have a finite service life and will eventually require replacement.

Depending on the battery type, they will typically have a design life of either 3–5 years or 7–10 years. Batteries in smaller plug-and-play UPS systems can often be replaced by the end user, while larger UPS systems require specialist handling. NSSE provides comprehensive battery replacement services, including safe removal, installation, testing and responsible disposal of the existing batteries.

The UPS system should be installed in a clean, well-ventilated and temperature-controlled environment. It should not be positioned directly beneath an air-conditioning unit, as condensation or water droplets could fall onto the equipment.

Environmental conditions can significantly affect the service life of the UPS, particularly its batteries and capacitors. These components are consumable items with finite operating lives, and maintaining a consistent ambient temperature of between 23°C and 25°C is recommended to maximise their design life and support the long-term reliability of the UPS system.

Yes. We recommend that every UPS system is inspected and serviced at least once a year to confirm that it remains in good working order and is capable of supporting the connected equipment when required.

A UPS contains several components that deteriorate with age and use, including batteries, cooling fans and capacitors. Regular servicing allows their condition to be assessed, helps identify signs of wear or deterioration and can highlight potential faults before they result in an unexpected failure.

Smaller plug-and-play UPS systems may only require a basic inspection, operational check and clean. Larger UPS systems should receive a more comprehensive service, including checks of the batteries, fans, internal components, alarms and operating parameters. Where site conditions allow, mains-failure and battery-runtime testing should also be carried out to confirm that the UPS transfers correctly to battery power and continues to support the critical load.

Planned preventative maintenance can help extend the useful life of the UPS, reduce the risk of unplanned downtime and provide reassurance that the system will operate correctly during a power interruption.

A manufacturer’s warranty and a UPS maintenance contract provide different levels of protection.

The manufacturer’s warranty will generally cover the cost of repairing or replacing parts if the UPS develops a fault during the warranty period. However, it will not usually include routine servicing, preventative maintenance or a guaranteed emergency response time. Attendance and repair times may also depend on the manufacturer’s warranty procedures and engineer availability.

A maintenance contract provides a more proactive level of support. This can include 24-hour emergency assistance, with an engineer attending site within a pre-agreed service level agreement following a breakdown. It also includes annual or six-monthly planned maintenance visits, during which the UPS, batteries, cooling fans and other internal components are inspected and tested.

Regular servicing helps identify deterioration or developing faults before they cause an unexpected failure. It can also reduce the risk of premature replacement of batteries, fans and other consumable components, helping to improve reliability and extend the useful life of the UPS system.

A maintenance contract therefore complements the manufacturer’s warranty by providing ongoing preventative care, defined emergency support and greater reassurance that the UPS will operate correctly when it is needed.

We recommend that hardwired UPS systems are installed with a Maintenance Bypass Switch (MBS), sometimes referred to as an External Maintenance Bypass Switch (EMBS).

A bypass switch allows the UPS to be safely isolated, serviced, repaired or replaced while the connected equipment continues to receive power directly from the mains supply. Without a suitable bypass arrangement, it may be necessary to shut down the critical load before work can be carried out on the UPS.

This is particularly important in environments such as healthcare facilities, financial institutions, data centres and other critical operations where interruption to the connected equipment could cause significant disruption.

A correctly designed bypass arrangement therefore provides greater operational flexibility and allows essential UPS maintenance or remedial work to be completed with minimal disruption. It is important to note, however, that while the load is operating through the maintenance bypass, it will not benefit from the power protection or battery backup normally provided by the UPS.

Of course. Our experienced technical sales team can provide expert advice by telephone or email, helping you identify the most suitable UPS system for your equipment, operating requirements and available budget.

We will consider factors such as the connected load, required runtime, power supply, installation environment, future expansion and the level of protection needed. For larger or more complex UPS projects, our engineers can also carry out a free-of-charge site survey at a convenient time.

Following the survey, we will provide practical guidance on the appropriate UPS technology and capacity, battery runtime, system location, electrical requirements and installation arrangements. This ensures that the proposed solution is correctly specified, suitable for the application and capable of providing reliable protection for your critical equipment.