Normal rogowski Coils

[prakash]

Hi i would like to aska very basic question. Why the rogowski coil dosent sense the magnetic fields due the conductors which are outside of it??

[Aziz]

Hi prakash,

I found basic infos for rogowski coils:
http://homepage.ntlworld.com/rocoil/

http://homepage.ntlworld.com/rocoil/Pr9.pdf

http://en.wikipedia.org/wiki/Rogowski_coil

http://www.matthewmassey.com/RogowskiCoil/


The answer is simple: the flux area of the coil is the sensing area. The flux area of the rogowski coil is a toroid and therefore not convenient for metal detecting.

I usually use the rogowski coil for pure low capacitance and low eddy current shielding over the main search coil. The rogowski coil must not short circuited and is an open end coil connected to ground potential.

Regards,
Aziz

[prakash]

Physical Undersatanding a rogowski operation

Dear sir, AZIZ guru thank u for explaination. But if i dodnt go mathematically and see the flux of the outer conductor cuts the coil windings and it must be sensed by it how it cancelled out by rogowski coil?? Can you pls explain physically!!!

[Aziz]

But if i dodnt go mathematically and see the flux of the outer conductor cuts the coil windings and it must be sensed by it how it cancelled out by rogowski coil?? Can you pls explain physically!!!

Hi prakash,

could you specify your question more in detail? I have difficulty in understanding it.

Normaly, the rogowski coil is used to measure the AC current flow through a conductor (wire) going through inner of the rogoswki coil. The current through the wire causes concentric magnetic fields, which are covered and sensed then by the rogoswki coil. A voltage induction can be measured.

For metal detection this coil type is really not convenient.
See attached graphics for more infos.

Regards,
Aziz

[Aziz]

Addition to your question:

When the wire to measure is outside of the rogowski coil, the total magnetic flux is getting zero. Therefore, it doesn't induce any signal from wire outside.

See physical details on wiki:
http://en.wikipedia.org/wiki/Magnetic_flux

Aziz