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Technical Discussions
India, Joined Feb 2017, 3


Joined Feb 2017
10:17 Mar-15-2017
MPI central conductor

What is the equation for current in central confuctor method?

Hamid Reza
Canada, Joined Oct 2016, 68

Hamid Reza

Joined Oct 2016
16:08 Mar-15-2017
Re: MPI central conductor
In Reply to Rio at 10:17 Mar-15-2017 (Opening).

Dear Rio,

It is a little more complicated than that. Is the conductor in the center or offset? Are you examining a round object? or Is it square or rectangular? Are you examining the outer surface or inner surface? What is the current wave form you are using? What is the ratio of conductor cross section to the part cross section (a.k.a fill factor). How many turns do you want to use (single pass, two pass, etc...)? What is the device you are using for magnetization? (e.g. Magnaflux P70, P1500? it dictates the number of passes). These are all the questions that need to be answered.

I suggest you read these:

1. ASME Sec V, 2015, Page 194, T-754.1 & T754.2

2. ASTM E709, 2015, & X3.2.1.2

3. ASTM E1444, 2016e1, X3.4 >---- important

4. BS EN ISO 9934-1, 2015, & A5

A simple formula to find a ballpark:

I = H x Perimeter

I = Current in ampere (RMS) >----- important to not that this is the RMS of the current waveform!
H = Tangential field strength (Kilo ampere per meter)
Perimeter = Perimeter in millimeters

Calculate the perimeter for outside if you want to inspect the outside and vice versa.

H = Assume that tangential field strength is 2KA/m

I = After finding the RMS value of the current, you have to convert it to the value of the waveform you are using. Refer to BS EN ISO 9934-1, 2015, A.9, Table A1.

Good luck.



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