Formula for pi or t lowpass filter?

What are the formulas for a lowpass pi or T filter for a given load and frequency? What I want to do is a lowpass filter for use between an inverter and a power transformer, to keep the inverter's harmonics (of

60 Hz) out of the transformer. In other words, pass 60 Hz (120V, 2A) to the load, keep the third and higher harmonics out. The attenuation is not too critical, just want to keep from overheating the transformer.
Reply to
Michael Moroney
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This website might help with the lowpass pi

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Reply to
Robert

Mike, I cannot help you with the actual design criteron of the filters however I can offer a few words on Harmonic filters.

Non linear loads such as the front end of an inverter tend to create harmonic currents which are a function of the load current and the inverter output voltage.

These currents change with the load and a low impedance path offered to them will certainly be taken

If there are high values of harmonic currents and your filter elements are not rated to carry these currents, then they will certainly fail, and catestropically, sometimes, as I have found out from Experience.

Most inverter manufacturers should have a "White Paper" dedicated to the design of the harmonic filters , giving specific details of harmonic currents generated for given loads.

See if you can find such things at the Manufacturers web site, but be prepared to "Over Design" a little rather then "Just big enough". Manufacturers tend to be a little conservitave with estimatesof harmonic currents.

Good Luck Tom

Reply to
Tom Grayson

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