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Measuring the current in an electrosurgical unit

  1. Nov 27, 2014 #1
    I have been trying to find an ammeter that can perform a specific task and failing miserably. I would appreciate any help I can get. and as you may soon notice, I have no engineering background.
    I am trying to find a non-invasive method for measuring the current generated in an electrosurgical unit (ESU) - the device that powers a bovie electrocautery device. The device changes voltage to keep power constant, depending on the amount of current passing through the a patient (resistance is constantly changing). The current that is used is in RF frequencies (350kHz-4MHz), to limit the effects on heart electrophysiology, and runs between 200-1000mA.
    I need a clamp on device that can be connected to a computer to give me real time measurements of the current while the bovie is in use.
    I cannot find an ammeter that will operate in RF frequencies and within those parameters.
    Does anyone know of a device commercially available that can do this? Does this type of device have to be custom built?
    I would appreciate any help I can get... thanks.
  2. jcsd
  3. Nov 27, 2014 #2
    You need a current probe. You can find plenty of them on market going up to few Mhz and several dozens of amps.
  4. Nov 27, 2014 #3
    If you know of one that you think could work, I would really appreciate it. I have been trying to find one for some time and I cannot. Please let me know.
  5. Nov 30, 2014 #4
    There are a variety of clamp-on probes intended for use with oscilloscopes. Of course, oscilloscopes are a natural instrument to visualize and measure in this range, but setting the ranges, zeroing, and capturing the information via labview might be a mess.

    RF meters are readily available that will plug into the 50 ohm outlet of the probe. Unfortunately, these tend to have a lower range between 10 and 50 MHz.

    So, as far as I've found you're either stuck with a PC controlled scope and probe or a probe with a custom RMS converter.

    Sorry I couldn't cook up something easier.

    - Mike
  6. Nov 30, 2014 #5


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  7. Nov 30, 2014 #6
    thanks for your help. i am calling these companies. I will let you guys know when i find a solution.
  8. Dec 1, 2014 #7
    I am not endorsing any company. And I have not received any products yet. But, Tektronix was the only company that was able provide/sell an appropriate current probe. They were also very helpful. FYI, if anyone needs something similar.
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