User:Enconengineers

Active Harmonic Filters – a case study with frequent Electronics cards Failures & High Energy Consumptions 

Active Harmonic Filter Technology is being used worldwide without giving much consideration to its Pros and Cons. This article based on real life case study is intended to bring out its pluses and minuses that would benefit the user industries and allow them to take a considered decision.

The major problems those are caused by Active Harmonics Filter arises out of its magnifying both the Total Voltage Harmonics Distortion (THDv) everywhere in the plant and the Total Current Harmonic Distortions (THDi) everywhere except at its input feeder.

Its performance is summarized below after switching those ON in smaller ratings totally 250A (10% of the Plants total running load) against the Transformer Capacity of 1500 KVA (rated), 415 Volts, 2500 Amps.

1.	THDv (Voltage), doubled everywhere in the plants Power Systems

2.	THDi (Current) increased up by 20 to 30% throughout plant, EXCEPT AT the INPUT OF the ACTIVE HARMONIC FILTER. This phenomenon as evident from the Electrical Single Line Diagram (SLD), is like a blind man’s seeing an elephant that mislead the user for the wrong conclusion.

3.	Active Power i.e. Energy (kWh) consumption increased up by 2 to 2.5% with just small 10% Active Harmonic Filter installations. However properly sized Active Harmonic Filter (or for that matter for the full plant loads of 2500A) would have increased Energy Waste between 10 to 15% levels.

4.	All the above factors exacerbated frequent failure of electronic card and nuisance tripping which were the reasons for the plant management to carry out this independent verification audit as well as carryout root-cause analysis for increased failures after installations of Active Harmonic Filter. The recommendations were to switch off those Active Harmonic Filters and since then electronic card rates reduced to earlier level.

Bold textNOTE: Unable to upload (or copy Paste) a PowerPoint drawing that depicts details of all measurements taken for this case study. Can someone Please advise how to upload or copy paste it here. my e-mail ID is <>Bold text