Slip Ring Noise

[MarkUMSU]

I want to use a slip ring to carry vibration data from the end of a rotor mounted on a slightly unbalanced shaft but have some reservations as I've seen other posts mentioning slip ring noise contaminating data.

I'm considering the Moog model AC6231. They claim acceptably low noise levels during normal operation up to 2500rpm, but have not been able to comment on the vibration threshold that will cause their slipring to begin to perform out of spec.

Can you comment on the performance of this component or other slip rings that have been used in vibration?

Thanks
M

 

[Strong]

Mark,
A quick look at the specs online indicates that this is for high current. I doubt that this type of slip ring is appropriate for carrying 100 mv AC instrument signals. You can keep looking for an instrument-grade slip ring, but I would use telemetry instead.

Walt

 

[IceStationZebra]

The added bonus with telemetry is that it is so much easier to mount. No trying to route past bearings, etc. Some single channel models are the same size as a 9v battery.

ISZ

 

[MarkUMSU]

OK. I'll look into it. Thanks

If you have a particular telemetry module to recommend, I'd love to take a look at it as a starting point.

I'm looking for at least 4 channels sampling @ 10kHz

Best

 

[IceStationZebra]

I have experience with the single channel Binsfeld TT9000, but it all depends on your particular situation.
-longevity of test, sensors in oil/water, self powered, number of channels, etc.

ISZ

 

[btrueblood]

For what it's worth, if the test duration can be limited:

We once instrumented parts that were failing from fatigue during our multi-step shop processing. One of the processes had the part being faced in a manual lathe. After a bit of debate, we ended up taking strain gage data directly out the tailstock of the lathe on about 12-15 feet of instrument wire, which we held in "gentle tension" while the lathe spooled up to 1000 rpm, did a 50-60 second cut, and stopped. The winding of the wire was then "undone" by reversing the lathe. Worked very well, the data was clean, and only a slow thermal shift (DC bias) that we had to correlate out later.

 

[GregLocock]

We used to take data off vehicles by driving along side them and running cables from the test vehicle to the plotters in the other vehicle.

I don't think I'd recommend that approach in general!

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[IceStationZebra]

Talking to the old guys at International Harvester they told me a similar story where they ran over the data acquisition umbilical cable over with a disc harrow (which has dozens of sharp 24" concave discs used to till farm fields) cutting it neatly into many 10" pieces!

ISZ

 

[btrueblood]

Greg,

You must have used a pickup truck for the chase vehicle, so that a guy in back could pay out the extension cord?

 

[GregLocock]

Nah, big old landrover, with a 20 foot boom on it.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[MarkUMSU]

you guys are incredible! But I can't say I'm not guilty of performing some pretty outragous tests on moving vehicles.

However, the duration of this test may be short, so I might consider the "gentle tension" with a long wire method when I need to add another data channel to my 4-channel slip ring.