How to measure Electrical noise

Discussion in 'General Electronics Chat' started by tekuteku, Dec 5, 2013.

  1. tekuteku

    Thread Starter New Member

    Dec 5, 2013
    Hi all,

    Background story:
    the project is related to checking vibration on rotating machine. during still standing engine, the vibration monitoring system is mounted on terminal box hanging on the engine frame, and then the monitoring is powered up. vibration is meassured by accelerometers of 10mV/g. what strange is that on still standing engine, the vibration monitoring system is showing 50mm/s RMS.

    Multimeter measurement accross the input channel it shows around 16 mV AC (RMS). But the engine is still standing. I was suspecting that the ground level is noisy, because when i connect measurement probe to oscilloscope (without the reference lead) it shows 50Hz noise at level of 50mV peak peak.

    1. Is my way of measuring noise with the osciloscope correct? if not, would you explain the best way to measure it?
    2. What can be causing the noise occuring on ground connection?
    3. How to design electronic that is immune to noise on ground floor?

  2. crutschow


    Mar 14, 2008
    What do you mean you measured with the oscilloscope "(without the reference lead"? Whats the reference lead, the ground lead?

    If you have a ground loop noise problem then you may need to use a differential instrumentation amplifier to isolate the measurement circuit from the sensor.