retrofitting variable speed drives to air compressors

retrofitting an inverter to a variable speed drive

Slow does, you're going too fast, you've got to make the power last!

First up: we're retrofitting an inverter to an air compressor because...? Well, becasue of the massive energy saving you can make - which we can show you in advance.

Well hang on there, not everyone knows what an inverter, converter, drive, variable speed drive is (and yes, they're the same thing). Unlike a softstart, (the clue's in the name) which slowly ramps up your motor (allowing a smooth progression of current) then allows it to run at a fixed speed, a variable speed drive takes over the running of your compressor 24/7, matching the production of air to the actual demand. So when you don't need air, you don't make air. This in turn will:

Save you energy (let's call it money and we'll prioritise this)

Give you greater control of your process

Equates to less wear and tear on your system

Reduce your discharge temperature

We guarantee there will be someone in your company who knows how much you're spending on electricity, but they're unlikely to know what it's being used on, or how much of it is being wasted. Once this information has been obtained - via an energy audit - you can see how much energy you really NEED to be using. And how you go about creating just the correct amount.

One of the easiest (and most economical) ways of achieving this is by retrofitting a variable speed drive to your fixed-speed compressor. This cost-effective approach can provide you with all the above benefits, with the fraction of the cost of a new VSD controlled compressor. We can clearly demonstrate the energy savings you can make - and they could be substantial, as we can show you in our case study  below.

A well-known car manufacturer uses oil-free air compressors for its process requirements in the press shop and body welding areas.

After undertaking an energy appraisal it was revealed that there was poor ‘Load’ to ‘Un-load’ ratio involving 4 compressors - with significant wasted energy.

The solution?

The Atlas Copco ZR 250 oil-free machines were converted to variable speed using ABB inverters. Auxiliary drives were fitted to the dryer to match the speed to the compressor.

And the existing energy air compressor management system software was modified to include the variable speed compressors.

The benefits?

* Total 5-year energy savings of £960,000
* An energy cost reduction of £1,000 per week per compressor
* Improved pressure control
* A promotion for the engineer who delivered the project

The picture below shows a fixed speed oil pump added to supply constant oil pressure during slow speed running as retrofitted compressors shouldn't have an oil-flow system which requires full speed for the proper flow of oil.

fixed speed oil pump

EDC Air Compressors works in partnership with our sister company, EDC (Scotland) Ltd, to undertake these retrofits. This ensures that you have specialist engineers from both fields working together to give you the perfect energy-efficient air compressor / variable speed drive solution. Our dedicated drive engineers can install, programme and set your new inverter controlled air compressor to run exactly as needed by your system requirements. And the work will be carried out as a seamless integration into your existing system.