Attempts energy saving by driving minimum required numbers of plural air compressors according to air consumption (Maximum controlled unit: eight units.). Digital pressure indication enables driving of the minimum number in precise pressure range. Further energy saving is materialized by the combination of inverter machine and standard unloader machine or plural unit control of inverter machine only.
Inverter machine runs preceding and stops last. Ideal driving is enabled as the standard machine runs with full load whereas the inverter machine runs by a controlled number of the rotation depending on load fluctuation.
Double loop driving with rotation function of inverter machine is viable.