EMC filters for VFDs?

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Murray,

Thanks for the Schaffner information and supplier. The price of the EMC filter is damn cheap compared to others I have seen.

Unfortunately I have gone for Siemens micromasters (420 and 440). Plus an odd Telemechanique VFD. The Siemens filters are eye watering and I have yet to find anything for the Telemechanique.

Regards,

Andrew.

[David JuppParticipant @davidjupp51506]

Don't presume that you'll need to add filters. Quite a lot of European brand VFDs will already have some filters built in – additional ones may be advised in some circumstances. I've fitted ultra low leakage additional filters on the mains input of some Lenze VFDs – these units cost almost as much as the (small) VFD itself.

Information on if there are integral filters isn't always the easiest stuff to find, at least with the major brands there is usually a tech support desk that you can call or e-mail to check.

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello David,

Thanks for your comments. Providing you get the covers off, then spotting an EMC filter on the input of the VFD is simple. I am glad that one does not have to do a filter on the outgoing. I didn't think you did and it would tax any filter to get rid of the HF generated by the Fourier transfer function for rapidly switched current. I misunderstood one of the replies thank goodness for mistakes sometimes.

Regards,

Andrew.

[Neil WyattModerator @neilwyatt]

Posted by SillyOldDuffer on 10/07/2018 10:55:01:

You can get an SDR dongle relatively cheaply <£200 and set them up fairly easily. Not really plug-and-play so unless you're interested in Radio (fascinating), the effort is probably too much for a play.

£200 = fairly cheaply?

Did you mean <£20?

Mine cost me £16.

Neil

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