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waveform generator isolation?!

Discussion in 'General Electronics Discussion' started by westnorth, Oct 26, 2012.

  1. westnorth

    westnorth

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    0
    Sep 14, 2012
    Recently , I heard the waveform generator isolation. The negative is not connected to the earth.Because I am an newer in electronic ,so I want to know something more.
    If the negative is non-grounded, is there a risk of electric shock?
    The output signal is very susceptible to noise interference ?
    I bought a waveform generator SDG1025 on ebay http://www.ebay.com/itm/Siglent-SDG...147?pt=LH_DefaultDomain_0&hash=item257118edfb, how can I test whether it's isolated?
    Thanks!
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
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    Nov 17, 2011
    The ebay article description gives no information on isolation. You can measure it using an Ohmmeter from the output socket to the protective earth wire of the power supply. If you measure anything below 10MegOhm it is not or not well isolated.

    There should be no risk of electric shock since the voltage output of the generator is most probably below 12 V (not detailed in the article description). Any dangerous voltages have to be insulated by design. Otherwise the manual has to state where and under what circumstances dangerous voltages are accessible and what precautions to take to avoid danger of an electrical shock.

    Noise is always a possible problem and not primarily related to insulation.
     
  3. westnorth

    westnorth

    7
    0
    Sep 14, 2012
    Yes,I can use my DMM to test it.
    If it's isolated, weather it will lead to the chassis with static electricity?
    The max output voltage is 20Vpp, but I don't think it means safe.When I input signal to a float test system , that means the negative of generator will have the same voltage with the test system's negative which is non-grounded, right? If the system's negative with high voltage,what will happen?
    This is my guess , and I may be wrong .
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
    1,925
    Nov 17, 2011
    If static is an issue, use a e.g. 100MegOhm resistor to ground to dischrage. But normally static electricity is not dangerous, just displeasing.

    20 V is safe.

    If the system you attache the genrator to is not safe, this is not an issue of the generator but of the system. There may be a reason why the system is not isolated. If you attach a grounded signal generator (or any other grounded equipmen) to the system, you run the risk of dangerous currents from the system to ground. If these currents run through the generator, the generator may even be destroyed.

    That is as much as can be said without detailed knowledge of the complete configuration and the operating conditions.

    By the way: You don't have to quote my full post. It is right before your answer.
     
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