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Need a non contact voltage sensor

  1. Nov 24, 2014 #1
    In the process of building my ebike I came across problems of measuring current without putting a sense resistor in the power circuit. For that we build a USB based non invasive current sensor which measures current from -100A to +100A. We also did a kickstarter although It looks like not many people need such a thing. I am not tryying to promote it here but trying to get ideas on adding a non contact voltage sensor

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    < Moderator Note -- kickstarter link deleted >

    In addition to sensing the current thru the loop I would like to sense the voltage of the wire. I am stymied any ideas on non contact voltage sensing similar to those ac power sensors sold by home depot but for DC and with 3 digit accuracy..
     
    Last edited by a moderator: Nov 25, 2014
  2. jcsd
  3. Nov 24, 2014 #2
    Measuring current is easy but measuring voltage without contact to a circuit is difficult, especially at low voltages. You can measure E-field and calibrate, but that's easier said than done.
     
  4. Nov 24, 2014 #3

    berkeman

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    Staff: Mentor

    Why do you need a non-contact voltage sensor? And can you just use a wireless link of some sort to make it non-contact? (Voltage sensor in contact with the voltage source, and transmits the voltage into to a "non-contact" wireless receiver)
     
  5. Nov 24, 2014 #4
    The sensor is non invasive for current. It uses a hall effect. It would be really cool if i could come up with some solution for measuring voltage at the same time. Never having to physically connect or touch high voltage /high current power lines.
     
  6. Nov 24, 2014 #5

    berkeman

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    Staff: Mentor

    It still would be helpful if you could mention what the application is. Do you just need to know whether the (AC) power is on? There are capacitive sensor units for that, as zoki85 has alluded to.
     
  7. Nov 24, 2014 #6
    In the ebike and evs the application is to measure power vs time so need both current and voltage. Normally people put a low res resistor in series to measure current. It is preferable not to break into the power cable and keep it sealed. In bigger evs like Nissan leaf you have 390v prime power so that is not a voltage you want running around. A sensor that goes on insulated wire is best.
     
  8. Nov 24, 2014 #7
    While the current has an unique value for a series circuit, the voltage will depend on which two points on the circuit you select. So I see a problem with selecting the points in a non-contact sensor.Maybe two sensors close but not touching the two points may do something.
     
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