A Canadian company which specialises in harmonic mitigation technologies has developed an auto-transformer combined with a harmonic filter, which tackles harmonic currents from low-voltage, six-pulse variable speed drives where the drive voltage rating differs from the supply voltage. The device, called the AutoTransLineator, provides either step-up or step-down voltage transformation.

“This is the only product on the market that provides the benefits of an autotransformer and the industry’s leading passive harmonics filter for six-pulse VSDs,” says Tony Hoevenaars, chief executive of Mirus International, the company which developed the system. 

Other methods for treating harmonics on low-voltage, six-pulse drive applications need either a special replacement 18-pulse drive, or a separate transformer to match the existing six-pulse drive voltage, along with tuned passive harmonic filters, or costly active harmonic filters.

The AutoTransLineator is said to deal with all of the major harmonics generated by drives and by other three-phase, six-pulse rectifier loads. It can be applied to a single drive or to a group, has a power factor of 0.98, lagging to 0.95, and an input current demand distortion of less than 5% on systems with a short-circuit ratio (Isc/IL) of less than 20. It is available in ratings from 45kW to 2.65MW, and in voltages up to 690V.