Standby Generators

Whilst the UPS system ensures that your IT equipment isn’t affected by short-term power outages, it is both uneconomic and impractical to size the batteries for more than 15 or 20 minutes of full load running. What is more, unless you have the cooling system on a UPS (which will increase the cost and space required by batteries considerably) then most modern data centres will soon overheat.

The answer therefore, if you need to keep your data centre live, is a standby generator.

The generator(s) should be sized to support the critical IT loads and their associated cooling equipment so that the data centre can continue running normally. With adequate fuel storage and a fill system that allows for re-fuelling with the generator running, power-cuts of any duration can be covered.

When selecting a generator careful consideration should be given to:

• Duty – the power rating must take into account power factors, start-up and step loads and battery charging
• Ventilation – if installed internally adequate ventilation for both combustion and cooling are needed
• Noise – generator engines are noisy so some form of acoustic treatment is essential. This can be from a standard enclosure which will typically give 82dB at 1 metre to purpose designed canopies able to meet whatever criteria is required (at a cost)

Diesel Rotary UPS (DRUPS)

Diesel rotary UPS systems combine the standby generator and the UPS into one unit. An alternator provides the power to the data centre and this is normally driven by the mains supply. In the event of a power failure a large flywheel keeps the alternator rotating while the diesel engine starts. Once the engine is running a clutch engages and the alternator is driven by the engine.

Benefits are:

• Power to the data centre is always isolated from any spikes, harmonics, brown-outs etc in the mains supply
• Not reliant on batteries