VSD compressors

With electricity prices set to double over the next few years and the federal government committed to reducing greenhouse gas emissions, buyers of new compressors should assess the energy-efficient benefits of variable speed drive (VSD) air compressors.

Unlike on/off load and variable output compressors (VOC), VSD compressors deliver reduced power costs, lower greenhouse gas emissions and can take advantage of money-saving utility tariff plans.

Many power companies are already offering attractive electricity tariffs to firms that do not exceed an agreed to ‘peak amps’ demand. This works in the customer’s favour, unless they exceed the allowable peak amps. If the peak amps limit is exceeded then severe penalties are imposed on the tariff charged. In some cases the customer could pay twice the original tariff rate for the next 24 hours.

Compressors with on/off load and VOC controls will typically require three to six times their normal running current at start-up. In many plants, it is common for compressors to have the largest electric motor on site, meaning they can easily be the cause of tripping the peak amps and increasing the electricity bill. This increased amp demand from compressors can occur several times a day, as most modern compressors shut down to save electricity during periods of low activity. Ironically, this small energy-saving feature can end up costing a large fortune through higher tariffs.

As VSD compressors are soft start, they do not draw more than full load amps at start-up. This ensures that the compressor will never be the cause of exceeding peak load amps.

Compressed air users should factor start-up current/amps into their equations when next purchasing a new compressor, even if they are not currently on a peak amp-type tariff. An on/off load or VOC control may preclude users from taking advantage of lower tariff peak amp contracts in the future.

With electricity prices on the rise and pressure to reduce greenhouse gas emissions mounting, it makes good economic and environmental sense to assess the benefits of VSD compressors.