Transformer with capacitive load.

Discussion in 'General Electronics Chat' started by Gibson486, May 16, 2013.

  1. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    I have an AC transformer. The load is purely capacitive....Do I want to ground the secondary side if I want consistent voltage across the capacitive load?
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    grounding one side of the secondary won´t change anything.
     
  3. Gibson486

    Thread Starter Member

    Jul 20, 2012
    199
    12
    Well, maybe I think I understand this right....

    When I measure the output (positive side of cap), it shows some voltage. However, when I ground the probe to the negative side, the voltage goes up. At first, I thought it was because there was a path to ground.

    I am guessing what is happening is that since the probe is high impedance, I am, in essence, creating a large valued resistor in parallel with the cap. This, as a result, increases current at the load, which also increases current at the primary side. Because more current flows, the voltage goes up on the secondary. Is that feasible?
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    No, not really.
    Where do you have the ground lead when you are measuring the presumably ungrounded secondary? Also how can you have a positive and negative side of cap if the only thing connected to the secondary is the cap? Better post a schematic of what you are actually doing.
     
  5. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    Here is a pic....
     
    • pic.bmp
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  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    As the transformer will isolate from the input, the ground on the output will not matter.
    Only the phase will change dependend on where the groud is.

    [​IMG]

    (I reposted your picture in a format that can be read in any browser).

    Bertus
     
  7. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Still no idea what instrument you are using, and what changes in the schematic and gives you higher voltage. Could you be a little bit more detailed about what you are doing and how?
     
  8. JayArr

    New Member

    Mar 11, 2013
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    When you measure the output the first time, with "some voltage" where is the ground lead of the scope attached?

    You know you can't read a voltage with only the positive probe and the ground not connected right?

    Voltage is measures "across" something so you need two reference points.
     
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