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Re: HT-37 transformer failure due to rapid STBY-->OFF-->STBY

Jim Whartenby All Messages By This Member #30493 Edited Why not just turn the switch, per the caution in the?HT-37?instruction manual, and avoid the problem?? If soft start and inrush were indeed a problem either one would have been addressed eons ago.? I love engineering as much as the next guy but I see no value in making anything fool proof.? For one thing, the item will never leave engineering and go into production. The equipment operator has to exercise some responsibility at some point.? Just saying, before operating, read the instruction manual, page 6, top left column. Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy On Tuesday, July 9, 2024 at 03:44:26 PM CDT, Lou VK3ALB <vk3alb@...> wrote: Hi all, What about combining a zero crossing switch with a soft start circuit giving a lower input voltage to the transformer for a handful of cycles before switching to fill voltage? Regards Lou VK3ALB toggle quoted message Show quoted text On Wed, Jul 10, 2024 at 6:28?AM don Root via <drootofallevil=[email protected]> wrote: Halden, now that everybody has been silent, ??? ???“would an SSR that turns on at zero voltage and turns off at zero current ????????????put the core back to zero every time and prevent current surges at turn-on” I looked around and can’t find just how much magnetism is normally left in good transformer steel. Sketches in tutorials are not to scale and deceiving IMO.? I recall real hysteresis curves from years ago, and ?there was a only a small amount of magnetization left.? Restoring it to zero is a tall order. ??The idea of removing magnetism is best displayed in tape head demagnetizers and such where the AC magnetizing force is gradually reduced. ? From: [email protected] [mailto:[email protected]] On Behalf Of Jim Whartenby via Sent: Friday, July 5, 2024 2:54 AM To: [email protected] Subject: Re: [HallicraftersRadios] HT-37 transformer failure due to rapid STBY-->OFF-->STBY ? Halden? I can't answer your question.? I don't know all of the pitfalls of using an SSR in place of a mechanical switch.? I don't know if there are any unintended consequences.? The SSR will turn ON and OFF at approximately the same part of the AC cycle every time so there may be an accumulative effect.? The random nature of a mechanical switch that has contact bounce would be very hard to repeat exactly and would be spread over a greater portion of the AC cycle.? ? Regards, Jim ? Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy ? ? On Thursday, July 4, 2024 at 03:48:33 PM CDT, HF via <incorridge=[email protected]> wrote: ? ? Hi Jim, Thanks!? So, would an SSR that turns on at zero voltage and turns off at zero current put the core back to zero every time and prevent current surges at turn-on? Halden -- don??? va3drl

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#30493

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