Xenobius Posted May 9, 2006 Report Share Posted May 9, 2006 Hi guys, I am looking for a circuit so that I can build a variable dummy load AC not DC. Could anyone help out? I am currently using rows and rows of 200W bulbs .. but they heat up too much. Any other IDEA apart from Resistors which are really really expensive?thankyouPS. I did find a DC dummy load here in the forums but as said.. its DC not ACTHANKS Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 9, 2006 Report Share Posted May 9, 2006 Hi Xenobius!I'm real curious ;D sounds like you are dealing with high power, what are you doing?What is the frequency, mains or higher and what is the maximum power the dummy load have to withstand? Quote Link to comment Share on other sites More sharing options...
ante Posted May 9, 2006 Report Share Posted May 9, 2006 Yes, I am curious too! I got an AC dummyload for 0 to 120kW; it’s a very expensive tool! Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 10, 2006 Author Report Share Posted May 10, 2006 Nice to see you are interested. Well I am working with 230vac at 50hz.I have some solidstate relays which I need to load to test them. I know its expensive but I still would like to give it a shot here Thanks guys!! Looking forward to your help as I am lost hehe :DWill post some pictures of it when I finish it (if I start it) hehe :P Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 10, 2006 Author Report Share Posted May 10, 2006 Yes, I am curious too! I got an AC dummyload for 0 to 120kW; it’s a very expensive tool!Cool did you buy it or did you make it? Do you have any pictures or anything?thanks :D :D Quote Link to comment Share on other sites More sharing options...
Muhammad Abu Bakar Posted May 10, 2006 Report Share Posted May 10, 2006 Hello Xenobius!I can remember something about the transformer properties. IT saysTo change the voltage levelv1= (n1 / n2 )*v2v1=secondary voltsv2=primary voltsn1=secondary turnsn2=primary turnssimilarly it transfers impedence to the other side by!Z1 = Z2 * (n1 / n2)^2 Z2 = actual impedence at one endZ1 = Effective transffered resistence at other end.and u can variation in Z1 with either changing (n1/n2) or Z2For fixed Z2, using a transformer with taps can help change turn ratio.An auto transformer can be used for the purpose. ( I have one in my REGULATOR with lot of taps and capable of voltage change upto 50%) Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 10, 2006 Author Report Share Posted May 10, 2006 hmm :o thanks mate. Do you think you can explain this a little better as I coudn't imagine how to doit. Thankyou !! Quote Link to comment Share on other sites More sharing options...
Ldanielrosa Posted May 10, 2006 Report Share Posted May 10, 2006 I am currently using rows and rows of 200W bulbs .. but they heat up too much. Any other IDEA apart from Resistors which are really really expensive?Well, with a dummy load you're facing a challenge turning the energy into anything besides heat.I don't know if it would be worth your while, but you could build your own resistors from a heating element. This would allow you to make whatever load you want. It would also reduce the startup surge that bulbs have. Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 10, 2006 Report Share Posted May 10, 2006 I remeber those big resistor packs they used to load heavy diesel generators when I worked in SAF, they were air cooled but represented only fixed loads not variable.I don't know if it is possible to wind own high power resistors with kanthal, alkrothal or nikrithal, honestly never tried with any of these but whatever dummy load you use you will have a lot of heat transfer.How is that 0-120Kw ac dummy built Ante?Have you checked inside this dummy load, don't say you haven't? ;D Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 10, 2006 Report Share Posted May 10, 2006 Ldanielrosa that's an good idea cold resistance of the bulbs results in high inrush current but on the other hand these relays should manage to cope this surge otherwise they will be useless in some applications. Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 10, 2006 Author Report Share Posted May 10, 2006 Yes I agree about the heat in the dummy load. Well at least its only Heat and not BANG .. there goes the bulb ... hehe Im still terribly interested in knowing more. For example about the DIY resistors .. using some special wire you said.. Any more information please?thanks guys please keep it up 8) Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 10, 2006 Report Share Posted May 10, 2006 Hmmm third post in a row ;DDummy loads I've built has been for RF and purely resistive, some of them has been air cooled or liquid cooled by oil and I have one which is made of two copper wires in salt/water solution (not for internal use ;D) that give 50ohms.Xenobius here is a link to something that might be of interest, this guy uses heating elements (same idea as Ldanielrosa had) that probably can be used from trashed washing machines for free:http://www.homepower.com/files/shuntregulationhp72.pdfwhat do you think?I read your last post, I will have to check up on the wire cause I have never tried it myself someone might have more on this. Quote Link to comment Share on other sites More sharing options...
Muhammad Abu Bakar Posted May 10, 2006 Report Share Posted May 10, 2006 Hello Xenobius!Can you tell us please which kind of source u r using for load test?A Generator, transformer or something elese.. Quote Link to comment Share on other sites More sharing options...
ante Posted May 10, 2006 Report Share Posted May 10, 2006 Hi Guys,Well I don’t own it, I just use it; I bought it for the company where I work for US$8000 including shipping. It’s the size of a suitcase, here it is: http://www.cannonloadbanks.com/l120.htmWorks perfectly, outstanding quality! Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 11, 2006 Author Report Share Posted May 11, 2006 Well I am using either single phase current which is 230VAC at 50Hz or 3 phase supply which is 400VAC between phases at same frequency. Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 11, 2006 Author Report Share Posted May 11, 2006 Hi Guys,Well I don’t own it, I just use it; I bought it for the company where I work for US$8000 including shipping. It’s the size of a suitcase, here it is: Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 12, 2006 Author Report Share Posted May 12, 2006 Ah no good for me because its only upto 200v and its for 400Hz :( Quote Link to comment Share on other sites More sharing options...
ante Posted May 12, 2006 Report Share Posted May 12, 2006 There are other models here : http://www.cannonloadbanks.com/PRICING.htmlYou have to ask, but I think the 60Hz versions will also work with 50Hz. Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 12, 2006 Report Share Posted May 12, 2006 Here is a schematic of a factory made dummy load from 1-32KW to much I guess ;D ofcourse it can be scaled down but the problem is still there on how to make those power resistors to fit your needs ::)http://babelfish.altavista.com/babelfish/tr Quote Link to comment Share on other sites More sharing options...
ante Posted May 13, 2006 Report Share Posted May 13, 2006 That was a bit fishy! ;DAm I missing something here? Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 13, 2006 Report Share Posted May 13, 2006 ;D ;D ;D ;D ;D ;D ;D :-[Me tooo!!Now I know that you can't simply link translated pages by babelfish, how pity!I got the link at work, I'll post it on monday in JP language, I've heard that you speak flawless Japaneese Ante ;D Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted May 13, 2006 Report Share Posted May 13, 2006 I found the link, it will probably not add any important info on the subject but this is how some of these AC dummy loads are made.Someone on this forum must have made their own power resistors with kanthal, alkrothal or nikrithal wire.Well, here's the link, if you don't understand use http://babelfish.altavista.com/ as translation tool ;)http://www.koowa.com/teikouki/huka/kouryu.html Quote Link to comment Share on other sites More sharing options...
ante Posted May 13, 2006 Report Share Posted May 13, 2006 No, not Japanese it’s Danish you must have heard wrong! ;D Quote Link to comment Share on other sites More sharing options...
Xenobius Posted May 15, 2006 Author Report Share Posted May 15, 2006 THANKS guys for your support I will check the links from home and let you know.Keep the discussion up.thanks Quote Link to comment Share on other sites More sharing options...
thermasearch Posted May 23, 2006 Report Share Posted May 23, 2006 HiFor a simple dummy load you can use a hot air gun. Quote Link to comment Share on other sites More sharing options...
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