Path: ...!2.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Klaus Vestergaard Kragelund Newsgroups: sci.electronics.design Subject: Re: CCFL transformer Date: Thu, 25 Apr 2024 22:28:54 +0200 Organization: A noiseless patient Spider Lines: 49 Message-ID: References: <66rk2jl35lbgd2tnqc6jjoqsd70ig9d485@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Thu, 25 Apr 2024 22:28:54 +0200 (CEST) Injection-Info: dont-email.me; posting-host="4b5c888e51d2a6be223cc6358a08a070"; logging-data="3365818"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+aQEZg8M9M82FQIWIZIlhrB1v8hl8P6Mk=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:9snq0GYE5mZMoiJMPKucjtn+AeU= Content-Language: en-US In-Reply-To: <66rk2jl35lbgd2tnqc6jjoqsd70ig9d485@4ax.com> Bytes: 2756 On 25-04-2024 16:52, legg wrote: > On Wed, 24 Apr 2024 01:57:36 +0200, Klaus Vestergaard Kragelund > wrote: > >> Hi >> >> I need a low distributed capacitance winding transformer, for a HV >> stepup function (3.5kV) >> >> I am zeroing in on similar concept as CCFL transformers with >> sectionalized bobbin. >> >> For example: >> >> https://www.coilcraft.com/en-us/products/transformers/power-transformers/ccfl-transformers/fl/ >> >> Possibly using Triple Insulated Wire to create some distance between the >> individual turns. >> >> Not many sells CCFLs these days. >> >> Guess I will keep it alive.... >> >> Regards >> >> Klaus > > Stress between turns is limited by v/n limit of core. It's layer > stress and section stress that you have to deal with. > That's what the multisection bobbin and pancake windings do. > Yes, but there will loss associated with the distributed capacitance between turns, that's why I am trying to reduce that one also > If the CCFL transformer will allow only 1600V, imagine the > precautions required for 3x that stress. I'm not sure you > can avoid vacuum impregnation / potting in anything 'small'. > I am actually working on an alternative idea, using 2 CCFL transformers, since as you write they are normally rated for 1600V. Incidentially, the 1600V is the start voltage, runs steady state at 600V. The idea is to parallel 2 CCFL transformers primary winding, and series connect the secondary windings. Then connect the center tap to GND, that way I get -1600V and +1600V, total 3200V without violating the ratings of the transformer