Electrical Review: ECO Mode And Other Steps To UPS Efficiency

We put ECO mode and Active ECO under the spotlight along with a few other ways data centre operators can improve their energy efficiency.

Electrical Review magazine’s October feature on energy efficiency provides us with the perfect platform to showcase some of the technological advances helping critical sites like data centres keep their power consumption down.

One likely impact of the coronavirus crisis is that more processing power will move to the cloud and the edge, as many organisations embrace the shift to remote working.

Add in the 5G revolution and data will play an even greater role in our future lives than it does even today.

But the Uptime Institute’s latest snapshot of the sector shows that efficiency is flatlining. While the gains of Moore’s Law are plateauing too.

How can data centres meet the demand for their services without a knock-on effect on their power consumption and environmental impact?

ECO Mode As An Option

Our article looks at various ways of improving UPS efficiency, including the benefits of modular UPS and replacing old legacy UPS with new transformerless units.

But it also focuses on the pros and cons of the various economy or energy-saving operating modes served up by UPS manufacturers.

ECO mode typically runs like a standby UPS. The mains powers the load – via the bypass line – and the inverter is switched off. There’s a temporary break in continuous power if the utility supply is interrupted while the inverter fires up and takes over the load.

Pure ECO mode guarantees operating efficiency up to 99%, much higher than the 93-97% you get from even the latest online UPS. A 2-6% improvement in efficiency equates to massive energy savings over the course of a year.

For a large data centre it could correspond to tens of thousands of pounds.

But ECO mode isn’t a panacea. It exposes your critical load to raw mains electricity – and all the drawbacks that can lead to. Vital equipment could go offline or be damaged by any sudden loss of power.

Technology doesn’t stand still though. And many suppliers now offer an Advanced ECO mode too. These Active ECO settings still see the bypass line power the load.

Crucially, however, the inverter stays on at all times. It runs in parallel with the input, so can pick up the slack far quicker if the mains fails.

In addition, the inverter absorbs harmonics and filters power in a similar way to traditional double-conversion online UPS mode.

Because of the extra energy needed to keep the inverter powered, Active ECO efficiency is 0.5-1% lower than standard ECO. But it’s obviously still higher than online mode.

It might not be appropriate for a critical site like a data centre or factory to always run in ECO or Active ECO mode. However, it could be a valid option to use when critical loads are inactive, perhaps overnight or out of hours.