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MSP430 based power meter and 10kV impulse

Dmitry Kubarev
Prodigy 190 points

I need to ensure the sustainability of a meter to the effects of 10kV pulse. What standard regulates parameters of these actions.

In slaa 409 as measures to ensure the resistance to high voltage is applied varistor and chip bead in the voltage inputs.

 Is that enough for resistance to 10kV pulse?

  • 0
    Guru 227245 points

    If you want to be sure, you can use a suppressor diode behind the bead and the voltage divider. Those diodes (also called Transil diodes) are effectively (and very quickly) shorting any overvoltage that may occur. They are not too precise (allow +-1V or so to the nominal value), but you can effectively limit the overvoltage so it won't destroy the MSP.

  • 0 in reply to Jens-Michael Gross
    Prodigy 190 points

    But for the voltage channel is used varistor. Necessary to provide stability to meter the pulse of 10kV. In slaa409 it is provided?

    In slaa409 used chip resistors in the channels of voltage and current. I fear that such resistors can not withstand 10kV impulse.

    What methods are commonly used to provide resistance to 10kV impulse?

  • 0 in reply to Dmitry Kubarev
    Guru 227245 points

    Dmitry Kubarev said:
    But for the voltage channel is used varistor

    varistors are slooooow. They are good to assimilate the energy of a pulse (some can swallow several kA), but way to slow to protect an electronic circuitry from a voltage peak. Hence the transil diode (which is faster than the typical input gate silicon) to break down the voltage, so the main voltage appears over the voltage divider head resistor (by effectively shortening the bottom resistor and therefore changing the divide ratio).

    Dmitry Kubarev said:
    In slaa409 used chip resistors in the channels of voltage and current. I fear that such resistors can not withstand 10kV impulse.

    Definitely not. To withstand 10kV, the worst case szenario defines 10mm air gap or 20mm surface creeping gap (as a rule of thumb).
    So only the 0.6W through-hole resistors will (nearly) fit the requirements. See their datasheet for details. The bottom resistor, however, only needs to be an SMD type.

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