Energy loss during unloaded running

What mainly determines a compressor’s actual specific energy consumption? It is the sum of efficiently and inefficiently used electricity consumed to produce 1 Nm3 of air.

Problems arise when the proportion of wasted energy is too high.

An extreme example is a measurement result at an automotive supplier. We measured production costs of CZK 1.80 per Nm3, caused by fluctuating demand and an unsuitable 22 kW compressor. Annual electricity costs were CZK 210,000, of which only CZK 45,000 represented energy effectively used to compress air.

We simulated an 11 kW compressor from the new VSD+ range with a variable-speed drive to continuously match fluctuating demand. Calculated savings of CZK 155,000 would repay the investment in around 1.5 years.