Traditional fixed-speed compressors run at a constant speed, regardless of the actual air demand. This means they often consume more energy than necessary, especially when the demand is low. VSD technology, on the other hand, allows the compressor to adjust its speed according to the air demand.
[pdf] They are used to keep the pressure in a tank between a pre-set lower and upper pressure. When the tank pressure crosses the upper or lower limit, an electrical switch is operated. Normally Closed (NC) switch.
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