Chris Healy wrote:
> Jeff, > > The normal practice is to wind a thermal protective device in the > transformer. For larger transformers it is normally a resetable device but > for small transformers, a one time operation type is often used. > > On Fri, > 4 Dec 1998, JENKINS, JEFF wrote: > > > Hi folks, > > > > I have a question about transformer fusing. I have an application that uses > > a 10W transformer connected across 400Vac mains. It is my understanding > > that this requires a fuse rated to at least 400V, which would mean 500V > > because that's the next larger size available. However, the smallest > > amperage fuse available at that voltage rating is 100mA. This by far > > exceeds the transformer rating. I thought about performing the EN 60742 > > test of loading the transformer until the primary current is 2.1 x 100 mA = > > 210 mA and taking thermal measurements, but I am quite sure the transformer > > will burn up under this large a load. > > > > The standards being used to evaluate this product are: > > EN 50178 > > UL 1012 > > CSA C22.2 No. 107.1 > > > > Any suggestions? > > > > Regards, > > > > Jeff Jenkins > > Senior Regulatory Compliance Engineer > > Advanced Energy Industries, Inc. > > Fort Collins, CO USA 80525 > > If you want to use low cost transformer without internal thermal protection you must protect your transformer: 1) for internal short circuit with primary fuse having nominal current near to the primary current 2) for overload with secondary fuse having nominal current near to the load current If you need useful info about transformers take a look at my web site. Ing. Fabio Milanesi e-mail: [email protected] http://www.freeyellow.com/members2/tcad --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
