If there is a drop in the DEWA supply, the server room needs a live double-conversion UPS that is the right size based on the measured kW. You should choose its battery runtime over its generator start time, and it should be kept in a room that stays below the temperature limit set by the maker.
If you get those four things right, the rest (brand, cabinet, and tracking) will take care of itself. This guide talks about the selection process, the heat issue that makes Dubai different from a datasheet written for Europe, and what you should ask for before you send a purchase order.
Which UPS type belongs in a server room?
Use live double-conversion (VFI) when the load can’t be affected by changes in voltage or frequency. Using IEC 62040-3, VFI is defined as an output that is not affected by changes in voltage or frequency on the incoming mains.
VFI-SS-111 is the best online classification. This class has line-interactive units and class has offline units. VFD and line-interactive systems don’t usually meet class 1 allowances during switchover.
Check the classification code on the datasheet rather than the product name. Our online UPS buyer’s guide covers the topologies in more depth.
| Type | IEC 62040-3 class | Output behaviour | Typical fit |
| Offline / standby | VFD | Load on mains until failure, then inverter | Non-critical small loads |
| Line-interactive | VI | Voltage regulated, frequency follows mains | Small racks, edge closets |
| Online double conversion | VFI | Rectifier and inverter always in the path | Server rooms with critical loads |
How to size a UPS for a server room
First measure the kW size, then look at the kVA grade, and finally add the growth before choosing a frame. Go through these in order:
- Measure the load. Take kW and kVA from PDU metering or a logger over a representative period, not from nameplates alone. Nameplates overstate real draw.
- Add a growth allowance. Set it from the client’s IT roadmap, not a rule of thumb. New switches and storage shelves usually arrive within a year or two.
- Check both limits. A UPS has a kVA rating and a kW rating. Size to whichever the load reaches first.
- Decide what is on the UPS. IT load, in-row cooling fans, network, security and BMS are separate decisions. Write the list down.
- Choose the redundancy. See the next section.
- Set the runtime target. Decide between bridging to generator start with margin and a controlled shutdown.
- Size the battery for end of life. End of life for VRLA batteries is commonly defined as the point where they hold only 80% of rated capacity.
- Add the UPS heat to the cooling load. One 40 kVA three-phase model’s datasheet lists 1,880 W of heat dissipation.
No, this is not a DCPS project. A measured 12 kW with a 30% growth limit equals a 15.6 kW design load. To get that done in 10 minutes, the battery will need 15.6 kW times (10 ÷ 60) hours times 0.8, which is 3.25 kWh of power. That’s before the manufacturer’s runtime tables make changes to the inverter’s efficiency and discharge rate.
Heat: the Dubai-specific constraint
The temperature affects both the battery life and the output power of the UPS, so the layout of the room is more important than the name on the cabinet.
VRLA batteries are made to work at temperatures around 25 °C. For every 10 °C above that, the life of the battery usually drops by half. Some manufacturers stick to the number 8 °C. So, a string that works fine at 25 °C will lose about half of its life if it stays at 35 °C for a long time.
Each type has a different output derating. One model of the Schneider Easy UPS is rated for full load from 0 to 40 °C and for 80% of maximum load between 40 and 50 °C.
That’s the curve for one type; read the curve for the unit you want to buy. The 40 kVA version shown above is protected from 0 to 40 °C by IP20 and has a dust filter built in. Part of the service plan for Gulf dust is to clean and fix the filters.
One situation calls for a clear design choice. In the event that the DEWA fails, the UPS and IT load will continue to run on battery power while the room heats up. Choose which cooling is powered by a generator and what the over-temperature alarm does.
Battery chemistry and runtime
Runtime should be based on what the battery is used for. Runtime doesn’t go in a straight line; most top numbers are given at a light load, and doubling the load cuts runtime by more than half. Use the runtime table from the manufacturer for your real load.
Under normal conditions, VRLA batteries in a UPS should last between 3 and 5 years. Plan for replacement early in the tenure, and don’t just guess what will work.
Not just the price, but also the way people talk about fire safety changes with lithium-ion. The UAE Fire and Life Safety Code covers places in the UAE that use lithium-ion batteries. It is enforced by Dubai Civil Defense and similar groups in other emirates.
Check with your fire consultant who is approved by the Civil Defense to see what standards apply to your room. You can also read the code on the Dubai Civil Defense page.
There are different fire codes for battery rooms, and the one that applies is decided by the authority that has power. Also, read the temperature clause in the battery guarantee. One company’s written terms cut the battery guarantee from 5 years to 2 years when it is continuously above 40 °C.
Redundancy: N, N+1 or 2N
| Configuration | Module failure | Maintenance without shutdown | Typical fit |
| N (single UPS) | Load moves to bypass, unprotected | Needs maintenance bypass; load unprotected during work | Smaller rooms, tolerable risk |
| N+1 (parallel) | Remaining modules carry the load | Yes, if load ≤ capacity with one module out | Most business-critical rooms |
| 2N (dual systems) | Second system carries the load | Yes, per system | Dual-corded loads, high availability |
The common mistake is buying N+1 and then loading the system past what remains with one module out.
Generator, distribution and protection
Ask for the rectifier’s input harmonic distortion and start-up behaviour before matching a generator. The 40 kVA datasheet above lists input harmonic distortion below 3% at full load. Our generator services page covers testing and ATS integration.
Two points of defense are missed. It is important to make sure that the downstream breakers can still tell the difference when the generator is in battery mode. Also, make sure that the plans for maintenance bypass and emergency shut-off are written down and tried.
DEWA, Civil Defence and other emirates
DEWA’s Regulations for Electrical Installations set the standard for installations in Dubai buildings. They talk about IET wiring rules and IEC standards, but DEWA’s rules are more important if they disagree. They are in charge of the system that brings power to and from the UPS, not the UPS itself.
IEC 62040-3 and the manufacturer’s instructions talk about how well the product works. Before you finish the single-line diagram, read the most recent DEWA rules.
Outside of Dubai, the utility and approval process is different. In Abu Dhabi and Al Ain, it’s ADDC/AADC, in Sharjah, it’s SEWA, and in the northern emirates, it’s EtihadWE. Do not use DEWA assumptions across.
What to ask for at commissioning
- A battery discharge test at real load, recorded against the datasheet
- Mains-fail and mains-return transfer tests, including generator changeover with the UPS online
- Bypass and maintenance-bypass procedure tests
- Alarm and network-monitoring tests, including over-temperature
- A thermal scan of terminations under load
- As-built single-line diagram, settings and test records handed over
Working with DCPS on a server-room UPS
The things that DCPS Middle East sells are UPS systems, power quality solutions, and technical studies like ETAP and load flow analysis. To get a quote on a server room UPS, send the single-line layout, the measured kW and kVA, the growth plan, information about the generator, and recent room temperature logs. Start from our UPS systems service or a load analysis study, read about our data centre infrastructure work, or contact the team