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#1 luclandry

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Posted 17 March 2006 - 07:44 PM

Hello everyone,
I am looking for two small variable frequency drive to put on a molding machine. We would like to have your opinions.

1) How much would it cost for a good frequency drive of about 1 hp that functions on 120 Vac or 240 Vac 1 phase with a nema 4x enclosure?

2) Is it necessary to have a filter of some kind to prevent harmonics distortions?

3) When we buy a drive do they usually come with a filter?

4) What type of filter is usually recommended?

Thanks for your help,
Luc Landry
Canada

#2 jraef

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Posted 17 March 2006 - 11:34 PM

Cost is relative. NEMA 4 narrows the field, I would contact someone who sells TB Woods drives in your part of Canada, they have a nice NEMA 4 package in that range. Figure maybe 400 - 500 $CDN?

The need for harmonic mitigation is determined by the installation, not the drive. Only the end user's engineer can answer that question. If it is a large facility who is very concerned about the cumulative effects of even small devices on their total harmonic distortion, then yes. If it's a drive in a farm all by itself, then the cost would outweigh the benefits in a lot of cases.

Drives that small do not usually come with filtering in North America, and even those that do include the type of filtering necessary for EMI/RFI interference, not specifically for harmonics.

The recommendation is dependant on the installation requirements mentioned above. All that said, a Line Reactor is always a good idea even if not for harmonics, because it can help to protect the drive from transients and short circuits. It will also reduces the harmonics as a side benefit, making it a good place to start.
"He's not dead, he's just pinin' for the fjords!"

#3 luclandry

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Posted 20 March 2006 - 04:38 PM

Thanks jraef for your answer.




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