promitheus inrush limiter
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Solid State Talk all about solid state amplification.

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 26th June 2006, 07:20 PM #1 morpheus82   diyAudio Member   Join Date: Oct 2004 promitheus inrush limiter hi all! maybe a lot of people uses the Promitheus circuit to limit the inrush current in the transformer when they power up their ampli, and i'd like to do it too, but i got some problems using the values he gives: the resistors blow up! so let's try to do some calculations... i have an 800VA transformer, 2x25V outputs, 2x 20.000uF, 220V line, so max current is 3,5A and to limit it now i'll use 80 ohm resistor, but how many watts?! and not less important...the RC doubles, so maybe I have to change the delay, but which are the components that determine the delay??ok, the 2 capacitors of 470uF but which resistor? please, if someone can give me some more specific formulas to fit this circuit i'll be very happy because i'm stopped with my diy amp!!!
 26th June 2006, 07:33 PM #2 BobEllis   diyAudio Member     Join Date: Sep 2003 Location: Upstate NY What are you using now? The resistor will initially dissipate 3.5 A x 240 V = 840W. Obviously you aren't going to put a kilowatt resistor in there. How much power handling you need depends on the delay before they are removed from the circuit and the resistors' thermal characteristics. You should probably be in the area of 50 W - so three 200R/15+W in parallel should be OK - a little higher inrush but not terrible. Higher power ratings wouldn't hurt.
 26th June 2006, 08:43 PM #3 morpheus82   diyAudio Member   Join Date: Oct 2004 sure!my calculation was the same, because he uses 4 series resistors 10ohms,5w, so 40 ohm 20 watts for 1200watts initial power...my intention was to use 4 series resistors 22ohm,5 watts in series, not parallel to have the same power dissipation. the transformer ratio is 9 so the resistor would be a (80/n^2)=1ohm at the secondary of the transformer, giving an rc of 20ms; the delay is about 0,5 sec(measured listening to the relay...)now, so the transient will be much more than fully completed!!!but i can't understand what's wrong with the first circuit, why the resistors blow up...
 26th June 2006, 08:54 PM #4 BobEllis   diyAudio Member     Join Date: Sep 2003 Location: Upstate NY I don't know the exact circuit you are using, but perhaps a wiring error. If the resistors are across the mains they will blow up. Verify that the resistors are in series with the mains line and that the relay closes across them when the delay trips.
 27th June 2006, 06:44 AM #5 morpheus82   diyAudio Member   Join Date: Oct 2004 this is the circuit: http://mitglied.lycos.de/Promitheus...for_toroids.htm do you know the formula to calculate the delay?and my rc calculation is right or i'm doing someting wrong?
 27th June 2006, 06:45 AM #6 morpheus82   diyAudio Member   Join Date: Oct 2004 ups...my first account is now working!raikkonen and morpheus82 is the same person...
 27th June 2006, 07:37 AM #7 Netlist   diyAudio Moderator Emeritus     Join Date: Jan 2003 Which one would you like to keep? /Hugo
 27th June 2006, 07:39 AM #8 morpheus82   diyAudio Member   Join Date: Oct 2004 if it will work also at home my old morpheus82, cos with the new one i'm under moderation...
peranders
Electrons are yellow and more is better!
diyAudio Member

Join Date: Apr 2002
Location: Göteborg, Sweden
Quote:
 Originally posted by morpheus82 this is the circuit: http://mitglied.lycos.de/Promitheus...for_toroids.htm do you know the formula to calculate the delay?and my rc calculation is right or i'm doing someting wrong?
The delay needed is about 300-500ms or so, only for the toroid to get magnetized. I use 100 ohms /4-5 watts at 300 or 600 ms and this works fine, has done so for 20 years.

http://www.diyaudio.com/forums/searc...der=descending
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 52 pcb's in order. 31 paid.

 27th June 2006, 08:07 AM #10 morpheus82   diyAudio Member   Join Date: Oct 2004 thanx a lot!but what did you change to obtain the delay you need?the 470uf capacitors?or a resistor?

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post lanchile Chip Amps 7 2nd February 2009 09:20 PM blmn Power Supplies 0 11th April 2006 03:20 AM roger-k Pass Labs 4 19th February 2006 07:42 PM jackinnj Solid State 60 28th December 2004 12:44 AM ljozsef Pass Labs 8 11th February 2004 09:40 PM

 New To Site? Need Help?

All times are GMT. The time now is 03:28 AM.