Recent content by Vladpl

Hello All I have a requirement to design an Isolation transformer(oil filled) with secondary being 15kV at 80kHz. To isolate the transformer I have looked into teflon, glass and other isolating materials. When looking at material specification I noticed that manufacturers always give corona...

Thanks for your input skogurra This is a serious project that I am undertaking at work. We had an engineer here who designed a similar circuit. Only problem is that it was drawing 14W and the 5W resistors he put in were very very hot, so I tried to alter the design. What goes after the circuit...

Hi All I am trying to design a circuit that will operate a power relay(30A). Mains voltage in AUS is 240V 50Hz. I have tried to design few circuits but none of them worked. Then I went to google and that didn't help me very much. My problem is that I haven't used timing circuits for a long...

Hi dap021 I work for a transformer company as transformer designer. We make transformers from .4VA to 50kVA single phase or three pahse. Really there isn't a standard size transformer when it gets to that rating. Only thing is if you need one now and the only one you can get is a 30kVA then...

I agree with davidbeach. It will be more likely that the transformer has been wound with copper instead of aluminium. Usually welding transformers consist of aluminium windings. Big distribution transformers have Cu. I have never heard of 2MVA transformer to have aluminium. I work for a...

I wouldn't be concerned about the electronics as well unless there is as jtkirb said a control transformer. All your transformers, motors, fans if they are designed for 60Hz only will run 20% harder if you connect them to 50Hz. This may result in transformer/motor burn out if it is run at the...

Hi All It is interesting that we all have the same thought on this topic. I just can't understand why doesn't the industry stand up and tell EU that what they are trying to do is irrational. May be if we all started protesting they would have to listen. I know that someone will profit from this...

Hi All Thanks for helping me out on this topic. Yes the normal transformer that you can buy (not an ideal transformer which would cost an arm and a leg) has a nominal inrush current at 10x which occurs mostly when a transformer that has a load is turned on. The highest inrush current will...

Hello guys I have designed many dc chokes (inductors). Now I have a job for a AC choke (Reactor). I have designed a few 3 phase reactors using formulas that I had form existing designs. So what I am asking is ... is there any differnce between a choke and a reactor? Would the design be the same...

Hello all and happy new year. I have a problem which is inrush current. The main problem I have that the transformer is being used as a power supply with mains outlets (you can plug in any mains powered equipment) the unit is 240V and rated at 10A. As you all know when you turn on a power...

Hello All As most of you know there is a big movement towards lead free solder. Europian Union has a law that from 1 July 2006 you will not be able to use lead solder ( military, medical, aircraft will be exempt). My question is that there is only 7 moths till that takes effect and I am unable...

Hello All Thank you all for your inputs. I have worked out why there seems to be the phenomenon in this coil. Since I am measuring it on the bridge the only thing left is that it is due to the capacitive coupling in the windings.Basicaly it works similar as the mutual inductance but in reverse...

Hello All Thank you for your replies. I know that there isn't much difference in the inductance. But I have been asked the question why when you series the two 200 turn windings the answer is not 1.4H and is instead 1.38H. Measuring with a very accurate bridge 400 turns makes it 1.4H. I am...

Hello All I have made a choke/inductor which has 400 turns on one side and 2 x 200 turns on the other side of the divided bobbin. My problem is that if I series the two 200 turn windings theoretically I should be getting the same inductance as the other 400 turns. But the thing is I am only...

Yeah I agree with skosgurra. I work for a transformer company designing transformers and power supplies. And in my 10 years of dealing with it no one asked me for such a thing. There are few ways saving on your bills apart from the obvios ones where you don't leave the lights or apliences on...