How detect a Leaky stator ?

[treez]

Hello,

We are designing and manufacturing electric motors. They have a stator of diameter about 40cm. This stator houses many power electronic inverter (H-Bridge) boards which help to drive the rotor.

These stators have like a water jacket in them which is for cooling.

Unfortunately, the stator iron has been welded in places next to where the inverter boards go and the cooling water is escaping through minute cracks in the welds and getting to the inverter boards. As you can imagine this has bad consequences.

Not all the welds leak in this way, but some do.

What we need is some way of detecting these minute cracks.

At the moment we are putting water with washing-up liquid in it over the weld and then pressurising the cooling water chamber with a car tyre foot-pump. -If there are cracks present then we should see bubbles in the water.

This is not a good way to detect the cracks however, and we need some better way.......someone here has heard of like a kind of electronic amplifier with a sensitive speaker which can be placed near the weld and it can "Listen" to it whilst air is being pumped into the water chamber.
-The amplifier would detect the "hiss" of air being pressured through the weld cracks, and we would know that there was a crack.

We are really clueless on this one, and would be most grateful for literally any thoughts or ideas at all on how to detect the prescence of these cracks.
-I doubt an xray would do it as the crack is surrounded by too much dense metal and the crack i doubt would show up.

Thankyou for reading.

 

[electricpete]

someone here has heard of like a kind of electronic amplifier with a sensitive speaker which can be placed near the weld and it can "Listen" to it whilst air is being pumped into the water chamber.

That would probably be an ultrasonic probe system with directional microphone. For example UE Systems Ultraprobe 9000.

Also you can use tracer gases and gas detectors.




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[edpaq]

Do a google search on NDT (Non destructive Testing) That will give you a multitude of options and information.

Eddie

 

[waross]

Take a look in the refrigeration industry. They use sonic leak detectors to detect and locate gas leaks. You can probably find an off the shelf sonic detector at a reasonable price.

Bill
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"Why not the best?"
Jimmy Carter

 

[BJC]

I think your in the wrong forum.
Try metalurgy or the mechanical other topics.
Lots of ways to detect defects in welds, magniflux, dye penetrate, etc. You'll find more answers in another form.
The science of welding has devoted lots of though and research into avoiding the problem you have. It's probably cheaper and better to correct the root casue than fix problems.