20A current transformer Amecon 5304

Discussion in 'General Electronics Chat' started by superway, Sep 16, 2013.

  1. superway

    Thread Starter Active Member

    Oct 19, 2009
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    Hello,

    How to test and verify a 20A Current Transfomer ( p/n Amecon 5304) is accurate reading? Because we found out a lot CTs read not accurate Amps when applied a low current 1A on it and compared the current between measurment (by current probe) and display ( on our Microboard). So that, we have to test every single CT first before installing on PCBA board.

    Thanks
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    What current waveform are you measuring or monitoring with the CT? Purely sinusoidal?
     
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Are you using the CT in the way shown on the data sheet?
     
  4. superway

    Thread Starter Active Member

    Oct 19, 2009
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    Hi Shortbus,

    Yes that's correct the picture.

    I used both measurments, scope (sinewave) and power meter to monitor the number.
    Thanks
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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  6. crutschow

    Expert

    Mar 14, 2008
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    What is the maximum current you need to measure? If less than 10A, you can increase sensitivity (and accuracy) by adding more primary turns, as Max noted.
     
  7. #12

    Expert

    Nov 30, 2010
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    That's a slick trick I use with a clamp meter. Ten turns around the arm of the clamp and a couple of alligator clips make a 6/10 amp scale to measure relay control current.
     
  8. superway

    Thread Starter Active Member

    Oct 19, 2009
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    This is fixed current transformer, please see picture AMECON 5304. I can't add more turns on it. The current i measured is 1A ( the turns ratio of CT: 1000:1). Thanks
     
  9. #12

    Expert

    Nov 30, 2010
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    They are talking about the .355 inch diameter hole in the center. If you can run the current carrying wire through the hole more than once, you can get a different turns relationship. If you are only measuring 1 amp, that can be done with a pretty small wire and you can get several turns of it through the hole.
     
  10. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    What I was talking about was the 100 Ohm load resistor across the secondary outputs of the transformer. Then you measure the voltage from that. Kind of like a Kelvin/4 point measurement.
     
  11. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    What I was talking about was the 100 Ohm load resistor across the secondary outputs of the transformer. Then you measure the voltage from that. Kind of like a Kelvin/4 point measurement.

    Like shown on the first page of the data sheet
     
  12. superway

    Thread Starter Active Member

    Oct 19, 2009
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    Hi Shortbus,

    I can set my variac AC source to 60Vac, then connect the LINE through CT donut and out to a power resistor 60 Ohm/250W. The NEUTRAL from variac connects to another end of power resistor. So that I can measure 1amp ac from primary, and the voltage (0.1V per Amp) from secondary.
    Any advise.

    Thanks
     
  13. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    The CT has to be used as shown in the data sheet. I circled in red the schematic from the page. Below the schematic is a graph showing the different voltage out puts that can be expected for different load resistor values.

    The Circuit you are using the CT in MUST have a load resistor in it for the CT to work as expected. If the circuit doesn't have the load resistor, it is not going to work reliably. If you don't have the load resistor in the circuit, this is probably why you are having so many failures in the product. CT are pretty simple and not prone to failure, can't believe they are bad from the factory.
     
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  14. superway

    Thread Starter Active Member

    Oct 19, 2009
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    Oh yes, I have a 100 ohm 1/4W load in secondary CT. Those CTs are not bad, the reason I try to measure is looking for CTs have more accurate reading voltage on secondary when applying small current 1A thru the donut. Some of 20A CTs have not accurate reading at lower amp, but to be more accurate at higher amp like 10A or 15A.

    Thanks
     
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