sensor for low level electric field

Dear friends:

I want to design a portable system for sense charged power lines and systems for human protection near power ssystems.
For this, I need a sensor for measure low level electric fields (which is about 20-30 V/M). Can you give me an advice about some semiconductor device for do it ?. Could you give some basics of principles for approach this problem?.

Thanks in advance

nebisman

Maybe you should focus on measuring the magnetic fields (static or not..) near power system facilities...

Especially in powerline distribution systems (e.g. high voltage powerline towers) the ELF magnetic fields are more apparent than electric fields.

Just a thought.
Magnetic sensors and transducers you can find from these companies:

http://www.bartington.com
http://www.sentron.ch
http://www.ssec.honeywell.com/magnetic/

Hope this helps...

mogwai.

Is not suitable to sense the magnetic field because near some systems the magnetic field can be negligible without load. Tha actual preference is to sense the EF.
For example , Does somebody know what is the sensor principle used by Non-Contact Voltage Detector as this:
http://www.testequipmentdepot.com/me...ters/vt201.htm

it could be a charge amplifier based device. A charge amplifier is a perfect sink for current, it behaves like an "infinite" capacitor, so it integrates current (i.e. measures charge) and gives an output proportional to the charge. Normally used to measure charge of fast pulses it could be use to measure estatic or slowly variable fields too. See http://ams.confex.com/ams/pdfpapers/57998.pdf.

I think you have to think in some kind of switching.

dQ = V dC + C dV

you cannot vary V, what you want to measure, i.e. dV = 0

So you have to strobe C ...