rovineye Posted February 27, 2002 Report Share Posted February 27, 2002 quote: Originally posted by ALHOLK: Hi! I do however doubt that many transformers are made with such tight specs that a step down from 60 to 50 Hz would make it overheat. I also believe that you might agree that after the AC to DC conversion the frequency doesn't really matter. I suppose the charge time could be affected though. regards ALHOLK [ February 26, 2002: Message edited by: ALHOLK ] ALHOLK, I didn't think they would be that close to the edge either, but blew a 60 hz battery charger over new years. It had been a long time since EE school for me also but recently went thru converting a ship that was outfitted with 50hz equipment and we were putting on 60 hz generators. So I had to freshen up. For sure, the rectified is too stupid to care about frequency. Link to comment Share on other sites More sharing options...
Mekong Posted February 27, 2002 Report Share Posted February 27, 2002 Come on guys lets get real, we are talking a primary to secondary step-down ratio, before bridge rectifier, frequency does not come into it. 99.9% of all chargers supplied with equipment in the last few years have a solid state "Voltage Detection Circuit" built into the primary, and via thyristor switching, it puts the primary voltage onto the correct tapping of the transformer, damn anyone with half a knowledge could build such a circuit and still have change out of 100Baht. Ripper, in reply to your original posting, it will be just fine, most electrical outlets in LOS accept both the Flat blade, and Round pin plug (if I remeber correctly USA is Flat blade), but you may run into difficulties finding an outlet with the earth receptical, hence why you will require an adaptor. CDK Meks Link to comment Share on other sites More sharing options...
Mekong Posted February 27, 2002 Report Share Posted February 27, 2002 Rovineye, get real. This posting is not intended as a flame, but I don't like to see people being misinformed. Frequency has fuck all to do with transformers. What matters is the ratio of primary to secondary coils to give the step down. Think about it, you step down the voltage, pass thru a diode bridge network, than have a capacitor on the ass-end for smoothing. I agree you have to size the components correctly for power rating, but not frequency. If you could tell me which formular you are referring to, to back up your statement, I may listen to your argument, but in my 20+ years of being involved in electrical engineering this is one of the dumbest statements I have ever heard. Link to comment Share on other sites More sharing options...
Guest Posted February 27, 2002 Report Share Posted February 27, 2002 Have to agree that frequency has nowt to do with it. I frequently plug my lap top into 100Hz 110V. The transformer runs a little hot at that frequency but that is it. Link to comment Share on other sites More sharing options...
Guest Posted February 27, 2002 Report Share Posted February 27, 2002 quote: Originally posted by Mekong: ...Frequency has fuck all to do with transformers. What matters is the ratio of primary to secondary coils to give the step down. Think about it, you step down the voltage, pass thru a diode bridge network, than have a capacitor on the ass-end for smoothing. I agree you have to size the components correctly for power rating, but not frequency... ...this is one of the dumbest statements I have ever heard. <big time snipping> The original poster asked a simple question about a power converter, not expecting a discussion of Ohm's Law. For a laugh, ask a TG to pronounce "electricity". Sounds a bit like "I like to eat pussy". Link to comment Share on other sites More sharing options...
rovineye Posted February 28, 2002 Report Share Posted February 28, 2002 quote: Originally posted by Mekong: Come on guys lets get real, we are talking a primary to secondary step-down ratio, before bridge rectifier, frequency does not come into it. Meks That doesn't make any sense. Of course it does come into it as I have explained. If it has frequency switching, or a higher rated transormer no problem. But it will be stated in the rating of the device. 50/60 hz on the device means no problem. If it only says 60 hz, don't risk it. It's that simple. Most (but not all) devices will be rated for dual frequency. Battery chargers for say AAs are another matter. Don't know why. Link to comment Share on other sites More sharing options...
rovineye Posted February 28, 2002 Report Share Posted February 28, 2002 quote: Originally posted by Mekong: Rovineye, get real. This posting is not intended as a flame, but I don't like to see people being misinformed. Frequency has fuck all to do with transformers. What matters is the ratio of primary to secondary coils to give the step down. If you could tell me which formular you are referring to, to back up your statement, I may listen to your argument, but in my 20+ years of being involved in electrical engineering this is one of the dumbest statements I have ever heard. Mekong, I don't take it personal nor as a flame. My simple explaination is thus: If the frequency applied to a transformer is increased, the inductive reactance of the windings is increased, causing a greater a.c. voltage drop across the windings and a lesser voltage drop across the load. An increase in the frequency applied to a transformer should not damage it. But, if the frequency applied to the transformer is decreased, (as in this case)the reactance of the windings is decreased and the current through the transformer winding is increased. If the decrease in frequency is enough, the resulting increase in current will damage the transformer. For this reason a transformer may be used at frequencies above its normal operating frequency, but not below that frequency. So take it or leave it. As they say "up to you". Sorry no xfmr formulas to drag up for you. Too busy packing for my departure for LOS tomorrow! Up until my last trip I would have pooh poohed all this also. But I blew up my AA charger, and it was only rated for 60hz. It was the xfmr. Must have been on the ragged edge and cheap. Splunge, I will take your suggestion and do an in depth survey of every beer bar, go-go, and MP to listen to the lovelies pronounce electricity. It sound like more fun than this discussion. I will report my findings. Link to comment Share on other sites More sharing options...
Guest Posted March 3, 2002 Report Share Posted March 3, 2002 Ok, for the formula minded, here is... EFFECTS OF FREQUENCY ON EFFICIENCY Due to the reactance found in a transformer, the frequency of the signal input into a transformer can effect the efficiency. From the equations XC = 1 / C = ½ fC and XI = 2 fL, it can be seen that the frequency does effect the reactance of the transformer which can effect the losses associated with these values. To determine the effect, the user can measure the power in versus the power out at different frequencies. BTW, also the circuit behind the rectifier is ofcourse frequency dependant. 50Hz through a bridge rectifier leaves a 100Hz ripple, needing a larger capacitor to compensate than the 120Hz ripple at 60Hz input. *Xan* [ March 03, 2002: Message edited by: Xantor123 ] Link to comment Share on other sites More sharing options...
Guest Posted March 3, 2002 Report Share Posted March 3, 2002 Guys -- I have a question about electricity that has nothing to do with battery chargers. I am in the beginning stages of planning a house to be built on my wife's fmaily's property upcountry. She is the deed holder. Anyway, so far I have learned that all houses in the district are dispensed an electicity usage allowance of 5 amps (!). I guess that's OK when all you're running is a couple of flourescent lights, a fridge, TV and maybe an iron once in a while. Of course, I am planning to use a lot more power than that. What I have in mind will require enough electricity to run one or two A/C's, incandescent lights, TV's, computers, a fridge, hot water heaters, etc. I sure don't want to worry about tripping a circuit breaker. I have some idea that the average house in the US uses maybe 200 amp service at 110v, but since the service in Thailand is 220 what effect does that have on the number of amps required? I have been told already that I will have to make an official request to the local district office if I want to increase the electrical service beyond 5 amps, listing what appliances I intend to use the power for. Anyway, any thoughts, ideas, recommendations? Link to comment Share on other sites More sharing options...
Guest Posted March 4, 2002 Report Share Posted March 4, 2002 Post deleted by DoxyBlue Link to comment Share on other sites More sharing options...
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