SKF new device for bearing current detection?

[Skogsgurra]

There is a rumour that SKF will soon reveal a new device for detecting electric erosion in bearings. I saw this in a Dutch release, but no details were given.

Anyone got in touch with this new gadget? Is it any good? Pricing? Other comments?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ischgl99]

We are interested in hearing about this as well, but won't be released here in the States until December.

 

[diskullman]

This sounds good in principal,but how many of these units could they possibly sell? Has there been a big demand for this type of monitoring? It would sell much better if they had a tool that would prevent electric erosion. I would assume a very high price.

Russell Giuliano

 

[williamoh]

Hello,
I tested SKF bearing erosion device on a VFD motor. If the rotor is not attached to anything, the device does not show anything. If the shaft is attached to somthing, then it shows the numbers on the screen of the device. I believe that the device is simply measuring the high frequency pulses as measring EMI/RFI signals. As long as the rotor has an antenna (attched equipment acts as an antenna or you have to make an antenna), the device works well. Without the antenna, it does not work. No way to tell whether the signals indicate the actual EDM in the bearing. The device may be used to detect EMI/RFI emission from the rotor of VFD motors.

William

 

[Skogsgurra]

Thanks William!

Was this SKF device the commercial unit that is going to be released in December? Or was it a pre-production unit?

When and how were you able to test it?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

On second thought - I think we know each other. Would lobster be a good hint?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[electricpete]

Here is some info. Note links to white paper and video etc:

http://www.mapro.skf.com/EDDpen/tked_frames.htm

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[Skogsgurra]

Thanks!

I found out that the device was on sale from December 1st. So I called my local SKF dealer and ordered one.

It just arrived and I will test it tonight. The cost wasn't very high, 4653 Swedish crowns or just below USD 600.

I will be back after I have tested it.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

I have now run a few tests with the TKED1 from SKF.

First impression: Little nice device that fits in your shirt poccket. Easy to handle. Batteries were almost DOA. Current consuption in OFF state is very low. But noticed that it can easily be turned on by EMI. Could be that it has been doing its thing in the box without anyone knowing it.

Second impression: Antenna breaks far too easily. SKF has obviously realized that. A spare antenna was delivered with the TKED1. But what when that antenna also breaks? Seems to be a question of a few seconds looking somewhere else. Or climbing a machine with the device in your shirt pocket. I guess that it has to be kept in the carrying case if it shall live more than a few days.

Test on bearing in test fixture: Works quite well. Indicates breakdown at levels around 5 V across bearing and antenna at about 100 mm distance. Well done!

Test on bearing in motor: Very difficult. PWM seems to override bearing signals. It will probably work on motors with a very good filter between VFD and motor and/or motor mounted on solid ground-plane.

A little quirk in the software: Rolls over from 99999 to zero and starts over again. That means that a measurement that should read 100123 reads 123. And that is something entirely different. The device was probably not meant to show numbers that high. But it does that easily when kept near a VFD drive/motor. Not a big problem. But could easily have been avoided if tested thoroughly IRL.

I don't know. It can be used to detect bearing EDM in DOL motors. But that is not where EDM is a problem. I will do some tests in a steel mill next week. They may have better grounds than I have in the lab and that will probably do the TKED1 better justice. But, OTOH, HVAC installations are very much like my lab installation. So, some hesitation as to its usefulness there.

Stay tuned!

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

Back after a rather thorough test of the TKED1 on around ten motors in a steel mill. Motor sizes in the 10 - 1000 kW range.

Conclusions:

I saw no EDM activity on the TKED1 when there was no activity in the bearings and the motors were DOL.

I saw varying degrees of EDM when motors were PWM driven. But more EDM close to the pecker box than close to the bearings. I think (am positive) that was due to EMI from motor voltage.

A good solid ground of the motor frame certainly helps reduce false indications on the TKED1, but one has to be careful and measure close to the shaft. Too close for comfort if there are protective covers.

Anyhow, I think that it is well worth testing on your drives. The price is OK.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[williamoh]

More test results:
We used it on some cooling tower motors to see if the device could detect the EDM events. The device did not show anything on one motor and show some signs on another motor. It did work well with a lead from a grounding brush when the lead is not connected to the frame or ground. Need more reseach to use the device properly in the field by maintenance personnel.

Gunnar, you are correct about the lobster. Have a great holiday!