How To Configure Backup Power Supplies for Hybrid Cloud Networking

The main reason for installing a backup power supply is to provide an instantaneous source of battery power for when the mains power supply fails or becomes unstable. Even momentary blips in the availability of your local electricity supply can lead to system downtime, hardware failure, damage, loss of service and data corruption.

Business Continuity and Cloud Computing

Over the last few years there has been a trend for organisations to a hybrid approach to Cloud computing as part of their business continuity plans. The approach is designed to mitigate disruption to on-premises systems and ensure and organisation can both quicky recover from a disaster and continue or bring back its service operation as fast as possible.

What is Hybrid Cloud Computing?

A hybrid approach is one where some information is backed-up and stored in the Cloud for remote access, and some data is held on-site for local processing via local area network.

The hybrid trend to storage and data management is now well entrenched in IT operations across the UK. In fact, the UK, was the third-largest cloud consumer in the world in 2020, behind China (second) and the US (first).
The market leading cloud providers run mega-datacentres, equipped to the highest availability and resilience ratings.

The top three global cloud providers include:

  • Amazon: Amazon Web Services (AWS)
  • Microsoft: Microsoft Azure
  • Google: Google Cloud Platform

Others include Alibaba Cloud, IBM Cloud, Oracle, and Salesforce SAP.

It is extremely rare for mega-datacentres to go off-line. These datacentres tend to be equipped with multiple redundancy levels in terms of their critical systems (cooling and power), IT server provision and even geographic datacentre coverage.

More information on Hybrid Clouds:

Local IT Network Connections

Information stored, accessed, and processed in a Cloud datacentre is only available when there is end-to-end continuity in terms of data pipe connections. Datacentres are benchmarked for availability and resilience using the Uptime Institutes Tier-rating system. The higher the tier-rating (moving from 1 to 4 being the highest), the more available the datacentre is, thanks to the configuration of its critical power and critical cooling systems.

You can expect the largest Cloud providers to operate Tier-4 rated operations. Smaller co-location datacentres may be Tier-4 but are more likely to operate at Tier-3 i.e., they have slightly less redundancy in their cooling and power and are so slightly more susceptible to interruptions.

More information on Datacentre availability ratings:

But what about the other end of the data pipe i.e., your local connection to the Cloud?

UPS Backup Protection for Computer Rooms and Server Rooms

Every organisation and company in the UK for example, will operate some form of computer room or server room. They may even refer to these rooms as their datacentres or mini datacentres. The reality is that a ‘datacentre’ is a building dedicated to IT servers and compute housing. It will include a data hall or server room, and around this all the necessary facilities and infrastructure required for the datacentre to operate. A typical data centre may operate from 10s to 1000s of IT servers.

On site computer rooms or server rooms tend to be smaller and may even only have only one server rack. The crucial point to note is that the even with only one server, the approach to backup power and UPS provision should be like that for a datacentre.

Whilst it is important to provide backup power protection for the local IT server(s) and networking infrastructure, connection to the outside world and Cloud also require UPS protection if continuity of service is to be maintained. This approach requires an audit of the local IT network to make sure that ever piece of comms equipment and networking devices are UPS backed-up and protected from mains power failures.

The amount of battery backup available from the UPS will be a function of the UPS the load size (VA or Watts or kVA or kW) and the battery Ampere-hour (Ah) supplied with the UPS. Most UPS are available with an internal battery to provide around 5-10minutes runtime. External battery packs can sometimes be connected to provide additional backup time. There may also be a local onsite power generator to take over the backup power function during prolonged power outages lasting several hours.

A comms room or server room UPS could be a floor standing type. The UPS will be installed in the room or somewhere adjacent, from where it will support the relevant circuits in the sub-distribution board.

A typical comms room or server room UPS is the CertaUPS 750 10kVA UPS, which is also available as a 20kVA UPS. The C750 rang uses online double conversion technology and incorporates an automatic bypass function. The UPS models can provide 3/1 or 1/1 configurations when installed. Here 3/1 refers to a three phase input UPS with a single-phase output and 1/1 refers to a single phase in and out UPS system. In the UK, the single-phase voltage is 230Vac 50Hz, and the three phase UK voltage is 400Vac 50Hz.

A UPS Power Supply for A Server Rack

For comms rooms and server rooms with one or more server racks or data cabinets, there are two approaches to provide UPS battery backup. The first is to provide power protection in the form of a centralised uninterruptible power supply system as discussed. Here a single UPS provides power to a dedicated IT electrical circuit. Every IT server, networking device and peripheral connected (plugged in or hardwired) to the UPS protected power circuit, will continue to operate during a mains power outage or momentary interruption.

An alternative power protection approach is a decentralised power supply. Here each server rack has its own dedicated UPS system. Typically, this will be by connecting each device to a rack power distribution unit (PDU or rack PDU) which is itself connected to the local server rack UPS. The PDUs can be installed to provide some redundancy in terms of A and B supplies, where the servers installed have dual power supplies.

Server rack ups systems tend to be 19inch rack mounted. Care must be taken when selecting the UPS to ensure there is sufficient room within the server rack in terms of internal depth to house the UPS. Also, to note is that if extra battery packs are required, these will take-up U-height within the rack which could be used for IT servers and routers.
Whilst most UPS still tend to use valve-regulated lead acid (VRLA) batteries in server room applications, there is growing interest in server rack UPS that use lithium-ion batteries. These tend to have a longer working life of 10 years or more compared to 3-4 and 7-8 years for a typical UPS VRLA battery. Lithium UPS batteries also recharge quicker (1-2 hours compared to 80% recharge within 24hours), are more tolerant of room or rack ambient temperatures above 25⁰C, and more compact, saving 30-40% space compared to a similar UPS using lead acid batteries. There is a price premium for Li-ion UPS of around 30%, however.

A typical lithium-battery powered server rack UPS is the APC Smart-UPS SRTL Li-ion 2200VA Rack Mount UPS.

Backup Power Supply for A Router

Within a building, Wi-Fi and network routers may be distributed and housed in data cabinets. For these it is important to identify which require backup power from momentary power failures, and which are required during a prolonged power outage for Cloud connectivity.

It may be that less critical Wi-Fi and network routers can be allowed to dropout during a power outage and only require a small battery backup system. These can be protected by less sophisticated uninterruptible power including a line interactive or standby UPS. Most UPS manufacturers provide tower and 19inch rackmount line interactive models. Standby UPS tend to be desktop or tower types. For installation this means deciding how to install them in a data cabinet. Where to connect them to the vertical struts and use slide out rails (if required) for a 19inch rackmount UPS or to ensure there is sufficient shelf space for a tower or desktop UPS.

The Eaton 5P 650VA 1U Rack UPS is ideal for small loads and data cabinet protection at only 1U high and 450mm deep with an internal battery.

A typical desktop style UPS that can be used to protect Wi-Fi and network routers is the CertaUPS C60 800VA UPS. This is a compact sized UPS with an internal battery providing around 3-10m runtime (load dependent). The UPS can be easily placed on a shelf and has four output C13 sockets with one offering surge protection only (mains power present), and three with backup power and surge protection.

The CertaUPS C60 800VA can also be used to provide power to local computer and workstation operators who need to ride through brief power outages and have enough time to shutdown their operations.

Home and Small Office Server Backup Uninterruptible Power Supplies

For small offices with a single server and network router, the installation may not have a server rack. The server could be floor standing with the network router placed nearby. This type of installation will usually be protected with a floor standing tower format UPS such as the Vertiv GXT5 1kVA/1kW Tower/Rack UPS.

A home office may need a smaller desktop UPS just for the broadband and Wi-Fi routers. Especially if working from laptops rather than desktop PCs. Small desktop UPS with multiple outlets can be ideal in this application such as the Eaton 3S 550VA UPS. Care has to be taken where the loads have AC adapters to choose a desktop UPS with either matching socket outlets (UK BS1363 rather than IEC C13) or to use a plug-in extension lead with a C14 plug. Battery runtime will be about 5minutes dependent on the connected devices and which sockets they connected to. As with other UPS, The Eaton 3S provides surge protected, and surge and battery protected outlets.

For some remote workers, their computers and home network may require longer battery backup if their availability is critical to the business continuity plan. Whilst a remote worker may be using home and Cloud computing, their connection to the company local area network may be via a VPN (virtual private network). A power outage where the remote worker is operating from, could cause a network issue for the company as a whole. Minimal risk but potentially one to consider for the IT manager and their department.

UPS Backup Power Configuration Checklist

For uses operating hybrid Clouds, it is crucial to have a well-planned approach to UPS backup power. The recommended approach is to audit the IT network and identify every device that could be protected by uninterruptible power supplies and to classify them into load types:

  • Critical Power Loads: IT servers and network routes that are critical to business continuity and will require power protection whether the power outage is momentary or a prolonged power outage lasting several hours. Critical power loads can also include computers and workstations that will be required to operate during the power outage to ensure service provision.
  • Essential Loads: less critical loads including those loads that can be allowed to drop out of service and are not required for the business continuity plan. Examples can include some local printers and Wi-Fi routers. These may only require UPS backup power protection from momentary power outages and if the mains power failure is going to be longer than say 10minutes, they will simply crash without detriment to the IT network or its connection to the Cloud.
  • Non-essential Loads: any other loads that do not require UPS protection and it not essential to operation of even a limited IT network or provision of service.

If you are in doubt how to classify a load, simply ask yourself ‘who complains?’ or ‘which stakeholder is impacted and for how long?’ if the device in question goes off-line during a power outage.


The weakest link when designing a backup power supply plan is that one critical networking device required for the IT network to operate and connect to the Cloud. A single router that is not protected by an uninterruptible power supply, could lead to loss of service and failure of a business continuity plan during a power outage. Therefore, it is important to conduct a complete system audit, document the asset list and classify them into the suggested load categories. The larger and more complex the network, the greater than chance to miss a critical device for a backup supply. The same can also be true for comms rooms, server rooms and server racks, which are poorly configured with incomplete power cord and network cable connections. If in doubt, talk to our Projects Team and arrange for a UPS site survey and audit.

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The primary role of an uninterruptible power supply is to provide backup power when there is a power outage, or the mains power supply becomes unstable, to keep the connected loads running. The amount of backup power available is dependent upon several factors.

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