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Electromagnetic interference effects on low level instrumentation

Electromagnetic interference effects on low level instrumentation

Electromagnetic interference effects on low level instrumentation

Does any one know what possible effects EMI from high voltage power lines would have on industrial equipment such as a PLC, or DC devices such as strain gage/loadcell amplifiers.  The ambient milli gauss from the power lines has been measured at approx. 47 mG, under the lines to about 10 mG @ 30 metres.  Line frequency is 50 Hz.
If there are potential effects, how can we minimise them?

RE: Electromagnetic interference effects on low level instrumentation

1.) Shielding
2.) Reducing the loop areas. ( induced VTG is proportional with field strenght, frequency and loop area.)
3.) 50 Hx notch filter or a high pass filter
4.) arrange the orientation of the loops to minimize pick-up.


RE: Electromagnetic interference effects on low level instrumentation

Don't worry about it as long as you are using good industrial grounding / shielding techniques. Load cell manf. are very helpful, the PLC manf. have dealt with this issue for more than 30 years.

47 mG is pretty small. If it is a 238 KV line then the biggest problem is electrostatic...

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