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It may seem obvious to use widely available analog devices MEME accelerometer for measurement in range of 0.5g. I did thorough study on this and found out that MEMS sensors either doesn't work or become erratic in high EMF surrounding. Since I wanted to measure transformer vibration and corresponding frequency by attaching the sensor on surface of transformer, it would always be in vicinity of high EMF.

There are industrial piezoelectric sensor available for this purpose but it doesn't detect small vibration in 0.5g range. There are industrial sensor available from National Instrument but looks very costly. Is there any particular segment of sensors which is recommended for this particular application?

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  • \$\begingroup\$ Do an experiment with a particular accelerator, as I'm not sure what they mean by 'high EMF' corresponds to the situation you'd find on a transformer core. Almost all the magnetic field travels in the core, very little through the air. Any electric field from the windings can be shielded by a wrapping of foil, if it turns out to be necessary, or putting the thing in a metal box. You may however have confidence problems when trying to figure out if the 50Hz signal you're seeing at the accelerometer output is real acceleration, or pickup from electromagnetic fields of the same frequency. \$\endgroup\$ – Neil_UK Jun 14 '18 at 14:00
  • \$\begingroup\$ What sort of vibration displacement are you expecting? What sort of vibration frequency are you expecting? \$\endgroup\$ – Nick Alexeev Jun 14 '18 at 21:24
  • \$\begingroup\$ @Neil_UK Placing the accelerometer 1mm away from the transformer core will sort that confidence problem out. \$\endgroup\$ – Dmitry Grigoryev Jun 25 '18 at 7:17
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If you google "optical displacement measurement vibration", you will find several potentially useful references. For example one system uses optical fibers to measure vibrations, as shown below. Optical sensors are immune to electrical interference.

enter image description here

While commercial sensors are expensive, you could perhaps make something yourself with a laser, a mirror, and and a DVD diode sensor. Here is a link to a paper that uses a laser pickup as an accelerometer, as shown below.

enter image description here

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1/2 g-force seems like a lot. Magnetically shield your sensor with mu metal and see if that helps. Make sure you use a shielded cable also and/or isolate the sensor and cable. In a high electric and magnetic field environment, it won't be easy to make a sensitive measurement like that.

Another way to do this would be to mechanically couple the MEM sensor while keeping it far away. One way to do this would be with a broom stick (or something more solid, the more solid it is the less mechanical dampening you'll have in the pole) which might get you far enough away from the transformer to make a decent measurement but still have the vibration travel up the sensor and get your measurement.

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