What is the main difference between a passive harmonic filter and an active harmonic filter (APF)?

Passive and active harmonic filters are used to improve power quality, but they do it in different ways. 

Learn the difference between the two types of filters and how each works.

Active filters

Active filters use power electronics to actively generate a reverse compensation current that cancels various harmonic components and improves power factor or other power quality parameters, such as voltage regulation and unbalance. 

In other words, they can solve 5 of the 7 main power quality problems. 

Active filters

Passive filters, on the other hand, do not use active power electronics. Instead, they use passive components such as reactors and capacitors tuned to a specific frequency to filter out a specific harmonic component and reduce the resulting harmonics. 

Passive filters can also compensate reactive power to improve power factor, solving 2 of the 7 main power quality problems. 
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The key difference between the two types of filters

In summary, the main difference between the two types of filters is the method they use to filter harmonic distortion and correct power factor.

· Passive filters use passive components tuned to a specific frequency, while active filters use power electronics to actively cancel harmonic components. 

· In addition, active filters have the added advantage of being able to consume single-phase reactive power when necessary, which optimizes power factor correction and improves voltage regulation and unbalance. 

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At Diram we have active filters and other products to optimize your current operation and implement a medium or low voltage solution that is in regulatory compliance. Contact our consultants to review the needs of your plant and recommend the best option for you.