# Resonance using Transformers

Discussion in 'The Projects Forum' started by HighVoltage!, May 28, 2015.

1. ### HighVoltage! Thread Starter Member

Apr 28, 2014
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Curiosity Testing:
I want to use two Current Transformers in series with a conductor in a loop to see how hot it can get by inducing AC current (1,000 amps and higher). However, one Current transformer will be fed from one source and the other from another. The first CT from first source I am allowed to get to resonance (pull less current from source/induce more current) if I only used it in the loop by it self.

Now that I have the second CT (rated the same) in the loop and from and second source, I am getting crazy numbers in the primaries. I am sure that I am generating some voltage across the terminals of the second CT, but if I raise simultaneously they seem to "level off" judging by CT primary currents.

I am wondering if there is a way to tune (reach resonance) with such a set-up with possibly two sources slightly out of phase? Both sources are capable of putting out same voltage. Does the second CT act as a load to loop? Does it also act as a load if I short the secondaries? Does the size of conductor act as a load?

The purpose is to put out more current on loop with half the primary value on each CT. Any suggestions?

Last edited: May 28, 2015
2. ### wmodavis Well-Known Member

Oct 23, 2010
737
150
How can "one Current transformer will be fed from one source and the other from another" if they are in series?
Confused! Please draw a diagram of what you are talking about and explain more of exactly you are trying to accomplish other than getting something hot.

3. ### HighVoltage! Thread Starter Member

Apr 28, 2014
95
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I am trying to reach a certain temperature on this conductor by inducing current through it. However, if I have one CT in the loop, it pulls lets say 80 amps at primary thats at resonance while only pulling about 5 amps from main source. Theoretically, if I use two CTS in series, at the same voltage and inducing the same amount of current, the currents should add up. Meaning: I would get double the output on loop while using same/limited primary currents.

4. ### wmodavis Well-Known Member

Oct 23, 2010
737
150
It would still be easier to understand if you drew a schematic. Resonance implies an LC circuit. Where does that fit in? What frequencies are you talking about?

5. ### AnalogKid Distinguished Member

Aug 1, 2013
4,709
1,301
Agree. No capacitance, no resonance. Also, no schematic, no answer. I'm thinking of making that my tagline.

ak

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6. ### alfacliff Well-Known Member

Dec 13, 2013
2,449
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it just soundls like transformer action. the primary 80 amps (one loop coil) and the secondary driven at 5 amps. lots of turns in the "secondary" and one turn in the "primary. in this case, running the ct backwards, driving the "secondary" and using the "primary as the Real secondary.

7. ### HighVoltage! Thread Starter Member

Apr 28, 2014
95
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Attached is the basic schematic for a better understanding. As described before ct1 can be tuned if you had it in the loop by itself and reach resonance. The second test set is just a variac power supply which just raises the voltage also controlling the output of CT2. Therefore, how I reach an equal output from both CTs from two different power sources. Hope this clarifies things.

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8. ### HighVoltage! Thread Starter Member

Apr 28, 2014
95
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Attached is the basic schematic for a better understanding. As described before ct1 can be tuned if you had it in the loop by itself and reach resonance. The second test set is just a variac power supply which just raises the voltage also controlling the output of CT2. Therefore, how I reach an equal output from both CTs from two different power sources. Hope this clarifies things.

9. ### HighVoltage! Thread Starter Member

Apr 28, 2014
95
0
The secondary (output) is the one loop coil. Theoretically CT1 at resonance BY ITSELF on the loop we can get infinite current but are maxed out based on wiring ampacity limits (TESTED). Not sure what you mean by run it backwards

10. ### kubeek AAC Fanatic!

Sep 20, 2005
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So the goal is to get lots of amps in a piece of wire? Why do you think you need some kind of resonance for that?

11. ### HighVoltage! Thread Starter Member

Apr 28, 2014
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It doesnt have to be at resonance. CT1 set is capable of tuning. However, all I want to do as mentioned before is get both CTs to read the same

12. ### kubeek AAC Fanatic!

Sep 20, 2005
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I thout that the CTs inject current into the loop, not measure it?

13. ### HighVoltage! Thread Starter Member

Apr 28, 2014
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Yes the CTs inject/induce current into the loop. The current in the loop is measured with a measuring CT

14. ### kubeek AAC Fanatic!

Sep 20, 2005
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You´re not making any sense.

15. ### HighVoltage! Thread Starter Member

Apr 28, 2014
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The CTs inject or induce current into the loop. All I said was the loop current is measured with a seperate CT.

16. ### kubeek AAC Fanatic!

Sep 20, 2005
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I didn´t mean post #13, I meant the whole thread.
You are using 2 CTs to feed one central circuit loop, and a third CT to measure that current? Apparently not, because in post #8 you are talking about "equal output from both CTs" and later explain that these are actually measuring CTs.
So now we have 4 CTs alltogether, two "power" ones and two for measuring.
Then comes some tuning and resonance, and the whole thing stops making any sense what so ever.

Can you please write down what exactly is the point of this contraption and what is it supposed to achieve and how?

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17. ### HighVoltage! Thread Starter Member

Apr 28, 2014
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CT1 and CT2 I believe are stepdown Transformers meaning lower voltage and higher current output on loop.
If I use on test set lets say CT 1, I get maxed out at 80 Amps on the primary side of CT (limit on wiring of test set/breaker).
If I get both CTs to get 40A on primary from two sources the out put should be the same as set up #1 because the currents should add up. This now means that I have more play room to go HIGHER in current in the loop because the limit is 80 amps on both test sets.
To monitor the output there is a small current transformer on loop to measure output, but that does not effect anything.

18. ### kubeek AAC Fanatic!

Sep 20, 2005
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What actually is that loop? Are you really after current or do you want more power?

19. ### HighVoltage! Thread Starter Member

Apr 28, 2014
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The loop is a copper conductor. I am performing stress analysis calculations, etc...I am looking for Higher Current.

20. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
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@HighVoltage!
What are the current transformers you are using or plan to use?
Can you post a pdf data sheet or a link to the actual type?
How much power do you need to get into your copper loop?
What do you mean by stress analysis in the context of your experiment?