One thing you might want to check is for any DC getting into the transformer. This can cause the transformer to saturate on one side of the sinewave, leading to high peak currents and a buzz. You can try checking for this by putting a DMM set to DC across the AC line. Should be well under a volt. Be sure to use a quality DMM, as cheaper ones might not be able to fully reject the AC, and some of it might show up as a DC reading. To make sure the meter isn't playing tricks on you, you can also try reversing the meter polarity and making sure the DC reading inverts too.
Admittedly, I haven't encountered this with an inverter before, just at a friend's apartment, where the DC caused an immediate breaker trip when a large 120->240 transformer was connected. I can sort of imagine a situation where an inverter that's not quite working quite right has a little DC offset at light loads, but that this goes away at heavier loads. Let us know what you find, Alex MeVay Genasun * Blue Sky Energy * http://sunforgellc.com On Mon, Jan 31, 2022 at 7:51 AM Foxfire Energy <d...@foxfire-energy.com> wrote: > > Not positive, but I’d suspect resonant frequencies.. might be simple as using > flat washers under the mounting screws.. maybe try adding an inductive load > to skew the power factor.. gobs of information online.. good luck. db > > Sent from my iPhone > > > On Jan 31, 2022, at 10:34 AM, drake.chamber...@redwoodalliance.org wrote: > > > > > > An Outback X-240 auto transformer on a VFX3648 buzzes loudly with a load of > > 400 W. The sound diminishes and finally stops with higher loads. > > > > The load was an electric, oil filled space heater. > > > > Has anyone seen this before? > > > > Thank you, > > > > Drake > > > > Drake Chamberlin > > Athens Electric LLC > > Ohio Electrical Contractor’s License 44810 > > CO Master Electrician’s License 4526 > > NABCEP Certified PV Installation Professional > > > > -- > > _______________________________________________ > > List sponsored by Redwood Alliance > > > > Pay optional member dues here: http://re-wrenches.org > > > > List Address: RE-wrenches@lists.re-wrenches.org > > > > Change listserver email address & settings: > > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > > > There are two list archives for searching. When one doesn't work, try the > > other: > > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > > > List rules & etiquette: > > http://www.re-wrenches.org/etiquette.htm > > > > Check out or update participant bios: > > http://www.members.re-wrenches.org > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > _______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
