We have a large number of small (1500rpm 100kW) diesel driven gensets (fitted with rolling element bearings at each end). These are located offshore on unmanned platforms and it is difficult to incorporate them into a routine detailed vibration monitoring program. Maintenance crews visit each platform for about half a day each month: I would like to equip them with a screening tool that would allow them to carry out a quick check on bearing condition, which would justify another visit by a vibration tech to carry out a full spectrum analysis if any concerns were raised. What I don't want to do is get all out maintenance techs going through vibration training courses.

A picture of the machine is in the attachment - a 12inch ruler is shown to give a sense of scale. When installed, there is no access to NDE H location. Forget making any vibration measurements on the diesels - we change them out for overhaul on an 'hours run' basis. Maybe we should do this with the generators...

One other problem: an attempt to address this issue was made about 6 years ago (before my time)and a small IS handheld meter capable of velocity rms and shock pulse readings was acquired, along with all the recommended gizmos and trending software. For some reason this kit was never used - I found it hidden under a desk in a remote location: the battery has never been inserted and the software remained unopened in its original packaging. I used this box in standalone mode, to get the shock pulse readings. Try as I might, I couldn't get the software to talk to the hardware - I have since found out from the OEM that the hardware and software (purchased together) are incompatible. This has generated a fair degree of cycnicism (How many of these things do we have to buy before we get one that does what we asked?), but it is an interesting challenge..

I would be interested in hearing from anyone with actual experience of making 'simple' measurements on similar items of inherently noisy equipment and has successfully picked up failing bearings? Can anyone with experience of making shock pulse measurements say that the readings obtained really are indicators of bearing condition and don't simply reflect diesel firing vibration or combustion noise?

Thanks in advance

Generators.doc (853 Kb, 48 downloads)

In my opinion, you can do a pretty good job using a simple vibe instrument for screening. You might want to look at some of the products at the reliability direct web site. http://www.reliabilitydirect.com/vibrationmeterproducts...rationmeterindex.htm They have several simple instruments, some with data storage and download capability.

Thanks for the reply Ed, I need to be sure that whatever we use really can distinguish between an alternator bearing showing signs of distress and the 'normal' levels of vibration transmitted through to the alternator from the diesel engine

vendor warning

There are units on the market that will do just what you are looking for. A simple route based unit that is preprogrammed for measuring the generators will allow someone with limited experience and training to take the measurements. The data gets loaded into a host computer where the data can be analyzed and trended and an indication of alarm level is also given to easily notify you that a more thorough analysis is required.

For the inaccessible horizontal location, you can add a junction box with a permanant sensor if the data from the vertical direction is not sufficient. Feel free to send me a message and I can go over some options for you.

Mike
http://www.fisna.com

Mike - thanks for the info, some of the items listed on the website look promising and I would like to know more.

I cannot figure out how to e-mail you, but I can be contacted on nr218pH_at_yahoo.com (replace _at_ with @)

I am based in Europe.

Some of the discussion here http://maintenanceforums.com/eve/forums/a/tpc/f/119103451/m/3421036241
can also apply. Most brutal way to start is by using a electronic stethoscope a glorified "yellow handle analyzer" but protect your hearing better, if you have a lot of exactly the same devices anyone will soon realize a difference btw. good ones and those getting worse, quick and easy and no computers. But relying on subjective human decisions, no numbers to trend but better than nothing. Olov

quote:

Originally posted by Buzz LightYear:
We have a large number of small (1500rpm 100kW) diesel driven gensets (fitted with rolling element bearings at each end). These are located offshore on unmanned platforms and it is difficult to incorporate them into a routine detailed vibration monitoring program. Maintenance crews visit each platform for about half a day each month: I would like to equip them with a screening tool that would allow them to carry out a quick check on bearing condition, which would justify another visit by a vibration tech to carry out a full spectrum analysis if any concerns were raised. What I don't want to do is get all out maintenance techs going through vibration training courses.

What is the purpose of the diesel gensets? For emergency power supply or to run continously?

Have you considered oil tests to detect the onset of bearing failure?