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891 views
05:59 Sep-02-2003

Ravi.C

NDT Inspector
Regional Engineering collage,
India,
Joined Sep 2003
2
Remote field eddy current testing

How to prepare probe for testing SA192 boiler tubes( 4.5 mm thick)? I have used 800 and 400 turns for exciter and receiver respectively with 3 times of the tube dia as a distance between the coils. But I am not able to get expected signal. Please tell me your suggestion on the same.


 
02:19 Sep-09-2003

Thirunavukkarasu

R & D
Indira Gandhi Centre for Atomic Research,
India,
Joined Sep 2003
2
Re: Remote field eddy current testing ----------- Start Original Message -----------
: How to prepare probe for testing SA192 boiler tubes( 4.5 mm thick)? I have used 800 and 400 turns for exciter and receiver respectively with 3 times of the tube dia as a distance between the coils. But I am not able to get expected signal. Please tell me your suggestion on the same.
------------ End Original Message ------------

Dear Mr. Ravi,

The receiver coil must be kept at remote field zone, Which you can find experimentally by moving the receiver coil. The distance need not be three times the ID of the tube. It may be more or less. Moreover you detection sensitivity largely depends on the instrumentation. Since the flux linkage in the receiver coil is very small the induced voltage will be of the order of micro/nano volts. It would be better if you use lock-in amplifier for the measurement of such voltages.


regards,
arasu


 
04:48 Sep-12-2003

Dana Ives

Engineering
CoreStar International Corp.,
USA,
Joined Jan 2003
10
Re: Remote field eddy current testing ----------- Start Original Message -----------
: : How to prepare probe for testing SA192 boiler tubes( 4.5 mm thick)? I have used 800 and 400 turns for exciter and receiver respectively with 3 times of the tube dia as a distance between the coils. But I am not able to get expected signal. Please tell me your suggestion on the same.
: Dear Mr. Ravi,
: The receiver coil must be kept at remote field zone, Which you can find experimentally by moving the receiver coil. The distance need not be three times the ID of the tube. It may be more or less. Moreover you detection sensitivity largely depends on the instrumentation. Since the flux linkage in the receiver coil is very small the induced voltage will be of the order of micro/nano volts. It would be better if you use lock-in amplifier for the measurement of such voltages.
:
: regards,
: arasu
------------ End Original Message ------------

Mrrs. Ravi and Arasu,
There is a direct correlation between induced voltage and the wire properties as well as the number of turns. A lock-in amp may help amplify the signal from the receiver(s), but I would think it would also amplify the inherent wire noise. Thus your S/N ratio may be inferior.


 
02:21 Oct-01-2003

Ravi C

NDT Inspector
Regional Engineering collage,
India,
Joined Sep 2003
2
Re: Remote field eddy current testing Dear Dana Ives
I used 800 turns in exciter mode and 400 turns in receiver mode. I need a details on selection of number of turns and technology behind it. Suggest me some article related on preparation RFECT probe.


 
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04:43 Mar-24-2004
Theo van Embden
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