Benefits and Function of VSD ( Variable Speed Drive)

The AUGUST S-T (variable frequency) Series is designed as a total concept, rather than by adding a frequency converter to an existing machine, it is tightly integrated and mechanically tested and has low vibration at high performance.

Main benefits are a highly stable air net pressure, low starting currents, a total absence of peaks and a high power factor.

By varying the speed of the drive motor, the AUGUST S-T (variable frequency) Series compressor output closely follows the air demand by covering

a wide range, without load-unload switching. The result is a constant pressure, without fluctuations, which greatly benefits to your overall process stability.

Furthermore, a great between 20% and 35% is achieved during partial load. The reduction in energy cost over a typical life cycle might even surpass the initial investment cost of the screw air compressor. In other words, the savings realized by VSD can pay for the entire machine.



The AUGUST S-T (variable frequency) Variable Speed Drive VSD Series comes in a ready-to-use package with many included standard features. The highly silencing canopy reduces the noise level to a mere 69-77db (A).

The compressor is delivered with an IP54 water and dust protected motor. (IP55 available upon request) The unit and the integrated frequency converter are controlled by microprocessor control and monitoring system.

This is enabling the Network buil ding for an ev en more efficient use of the AUGUST brand compressor, by combing a regular drive AUGUST screw air compressor with the AUGUST S-T series AUGUST VSD compressor. As a result of the networking you get the fully automatic function , that the AUGUST S-T VSD compressor is only filling up the current demand of the air, while the standard AUGUST screw air compressor is doing the base load of the air tank whenever required by the work load. This is the most efficient way of use of VSD.

VSD provides a soft start similar to a Y- transformation or electronic starter. This is extending the all over life time of the compressor unit and reducing costs for maintenance. Also the down-time can be reduced significantly and no or low vibration can extend the product life cycle too.

In the low speed period, the AUGUST VSD compressor is convincing by a comfortable noise level but will still only be between 69-77db (A) (depending on model) at full load, which will have a positive influence on the working environment and might even increase the productivity of nearby workstations.

Further advantage of the VSD AUGUST S-T series is the application in countries with 50Hz as well as 60HZ electric frequency.

A selected variation of voltages can also be supplied upon your request All models o f the series comply wit h the C E certification and when required have the ASME approved oil-air separator.

Energy efficiency

Independent studies have shown that energy can mount up to over 70% of a compressor’s lif ecy cle costs. In some cases the generating of compressed air can account for more than 40% of a plant’s total electricity bill. Most production environments have a fluctuating air demand depending on the time of day, week, or even months of the year from 35 to 78%.

AUGUST VSD reduces energy costs by:

  1. Avoiding electricity surges by Increasing flexibility with soft starting gradual motor up.
  2. Avoiding operation at no load power compared with conventional compressors at light load. Eliminating the inefficient transition period from full to no load power.
  3. Maintaining the net pressure band to within 0.10 bar, 0.01 Mpa
  4. Reducing overall average working pressure.
  5. Minimizing system leakage due to a lower system pressure.
  6. Preventing components from early aging cause by prolonged full load operation currents, a total absence of peaks and a high power factor.