High power variable resistor?

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Flyback

Well-Known Member
Hello,

I need to make or get a 40W variable resistance , which is to be as non inductive as possible.

It will carry a current which is a constant 1.9Arms , 50kHz , sinusoidal current.

So the resistance has to be variable from zero Ohms to about 11 Ohms.

Ive found this but its too high resistance and looks rather too inductive
**broken link removed**

Do you know who makes these things?
 
each resistor "step" is 11R, and i want the variable one to go from 0 to 11R so as to "get" each resistance value in between the steps.....so each step is about [(342/17)^2]/11 W max..so around the 40W mark.
 
Flyback said:
each resistor "step" is 11R, and i want the variable one to go from 0 to 11R so as to "get" each resistance value in between the steps.....so each step is about [(342/17)^2]/11 W max..so around the 40W mark.
Click to expand...


Umm, yea. You need to go back to school. How did you come up with that equation?

Let's see you have a constant 1.9A of current at fixed ~342VAC (according to your other posts) which is about 650W of power. It also means the load is a constant 180Ω

Again this has got to be a wonky student project, although far worse if you're part of an actual firm trying to clone that iSotech device. Your manager could be playing tricks on you, kind of like kids at camp that are sent on Snipe hunts.
 
Let's see you have a constant 1.9A of current at fixed ~342VAC (according to your other posts) which is about 650W of power. It also means the load is a constant 180Ω
Click to expand...

Constant current but not fixed voltage. I made the same mistake.
 
No offense, but I'm not sure the OP should be doing anything with 342VAC. Seems he'll probably kill himself with that kind of voltage and current, especially after showing this much inexperience!
 
Aww, you guys. Flyback is not that bad he is just one of those guys that 's hard to confuse with facts once his mind is made up. But you have to admit he comes up with some unique problems. I'm going to run over and give him a good click to see if I can turn him green.
 
DerStrom8 said:
No offense, but I'm not sure the OP should be doing anything with 342VAC. Seems he'll probably kill himself with that kind of voltage and current, especially after showing this much inexperience!
Click to expand...
It's in his other post.
 
ronv said:
Maybe something like this? I don't know.....

https://www.electro-tech-online.com/custompdfs/2013/07/FlatHCLV.pdf
Click to expand...

Well I'll be monkeys uncle. I've never seen that or heard of that. Flyback, iSotera and anyone else my apologies, turns out I was wrong. And Flyback I suggest you read that PDF thoroughly, it pretty much details the coupling. I couldn't figure out the efficiency but the current is there. They do seem to favor higher frequencies such as 250kHz.
 
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