Path: csiph.com!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail From: Folderol Newsgroups: comp.sys.raspberry-pi Subject: Re: controlling a mains-powered oven Date: Wed, 16 Dec 2015 10:01:07 +0000 Organization: A noiseless patient Spider Lines: 39 Message-ID: <20151216100107.43ccfde2@debian> References: <0CLay.46526$051.33662@fx28.iad> <9kg*YMWMv@news.chiark.greenend.org.uk> <_I4cy.38$xz4.32@fx12.iad> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Injection-Info: mx02.eternal-september.org; posting-host="4c8c017bf2000d02e906f28de06f0c9d"; logging-data="4635"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19H7+pPft6eYJqNah1Y5hhihvpyXW6s2C0=" X-Newsreader: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) Cancel-Lock: sha1:asDFuWaPzconLTbuhE4C7fGULpo= Xref: csiph.com comp.sys.raspberry-pi:10149 On Tue, 15 Dec 2015 22:17:16 -0500 Charlie wrote: > On 12/12/2015 8:53 AM, Theo Markettos wrote: > > Charlie wrote: > >> I applaud your ingenuity. > >> That said, if I had to do such a thing, I'd likely just order an > >> industrial panel unit that measures temperature and contains enough > >> "stuff" to control such things as ovens and heaters. > > > > FWIW we just bought one of these: > > http://www.beta-estore.com/rkuk/order_product_details.html?wg=1&p=242 > > which they also sell with a cheap oven: > > http://www.beta-estore.com/rkuk/order_product_details.html?wg=1&p=16 > > > > We haven't had a chance to get the hang of it yet, but since everything is > > sold as a kit it seems to work together reasonably well. This is for > > soldering rather than baking, but the same principle holds. The EUR119 for > > the controller is less time, hassle and risk of blowing things up than > > trying to make one ourselves. > > > > The controller output won't do more than 1.5kW, but secondary switching > > (eg a mains relay) should handle that. > > > > Theo > > > I'd be tempted to use any conventional oven temperature control present > as a backup do not go above temperature setting. Relay contacts have > been known to occasionally fail closed. If I remember correctly, 50hz is > harder on contacts than 60hz. > > It becomes a matter of how far do you go? There is *no* kind of disconnector that can't fail with the contacts fused, but in over 50 years industrial experience I've only come across it once, and that was because a fire in the cabinet warped the plastic housing. -- W J G