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bharath boss
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Hydro Generator-Upper Guide Bearing - Oil Spillage

11/08/2019 1:58 PM

Hi,

A vertical Hydro generator machine (pelton turbine) having an upper guide bearing (UGB) is facing an oil leakage from its UGB cover. Recently the UGB's cover rubber oil seal was replaced with Namda felt packing which was used to prevent the oil spinning from UGB to the outside. But within a month, oil spill was detected. Need help on selection of exact sizing of Namda packing or any other seal to prevent the oil leak.

Thanks

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Pathfinder Tags: hydro generator oil leak upper guide bearing
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SolarEagle
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#1

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/08/2019 2:29 PM

I would start over...

https://www.efficientplantmag.com/2014/02/selecting-the-correct-bearing-seal/

http://www.allsealsinc.com/FeltGasketsWashers.html

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Rixter
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#2

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/08/2019 3:01 PM

Contact the manufacturer of the turbine about a replacement rubber seal for the UGB cover. Apparently the Namda felt is not sealing it.
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HiTekRedNek
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#3

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/08/2019 4:48 PM

Check the bearing for excessive play.

Check the shaft in the seal area for grooving or wear.

The shaft may require machining,or a Redi-Sleeve may be required.

This is a very thin bushing that is pressed onto the shaft to restore a smooth surface.

https://www.timken.com/products/timken-mechanical-power-transmission-products/seals/

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bharath boss
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#6
In reply to #3

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/10/2019 1:32 PM

Basically I am from Electrical Engineering. But I need to resolve this issue even though it comes under the mechanical department. I need help on this.

Before the machine Overhauling, there was no oil leak. Also the rubber seals were used. But after the overhauling of Hydro generator, instead of rubber seal,I went for felt packing. Namda packing was used since other generators have the same felt packing with no oil leak issues. Actually, UGB is placed just above the thrust bearing. Oil circulation happens due to centrifugal force and comes till the UGB cover and gets back to UGB through the two small holes.

As you said, machining has to be done. But in this case it is not so. The past history of the machine was running well without any oil leakage.

My doubt is whether the felt packing should be fixed with a little "mm" of air gap? or Whether poor quality of felt may be the cause?

One thing I have noticed is the namda felt packing in oil spilling machine is made to rub against the shaft so tightly (Eg: like a shirt collar around the neck). whereas the other machines having namda felt packing is made to rub against the shaft with a slight touch(Eg: like a round neck collar around the neck). Will this be a cause?

Sorry for the poor example!

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SolarEagle
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#9
In reply to #6

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/10/2019 3:09 PM

The packing should have a very light pressure on the shaft, it sounds like it is not installed properly, or wrong size....maybe 0.3mm clearance...

https://www.machinedesign.com/news/felt-seals

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yesyen
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#4

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/09/2019 11:47 AM

Can you upload a simple sketch to have better understanding?

What is the shaft size and type of bearing?

While the issue is with upper guide bearing, what about the other bearing?

Why felt, why not oil seal? How much is shaft movement/wobble?

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bharath boss
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#8
In reply to #4

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/10/2019 1:39 PM

Will upload hand sketch soon.

Beneath the UGB, Thrust bearing (roller springs inside in it) is used. The bearing temperature of the same is little bit high after the overhauling.

Thank you.

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HiTekRedNek
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#5

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/09/2019 1:50 PM

Why was the rubber seal replaced with a felt seal?

Does the shaft have too much clearance in the bearing,causing the shaft to wobble?

If so,this problem must be corrected first.

More information gives better answers.

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bharath boss
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#7
In reply to #5

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/10/2019 1:36 PM

I guess the same Sir. But there is a wobble above the UGB. (i.e) exciter(dc excitation). Will consider this clearance issue too.

Thank you.

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PWSlack
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#10

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

11/14/2019 12:15 PM

The <...help...> is obtained over a telephone call to the <...Hydro generator machine...>'s original equipment manufacturer.

Invitation declined.

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bharath boss
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#11

Re: Hydro Generator-Upper Guide Bearing - Oil Spillage

05/22/2020 11:05 AM

Hi all,

Rectified the oil spillage problem. Specified Namtha felt packing was removed and Silicon rubber sheet was replaced and found no oil spill so far.

Thank you for the reply.

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bharath boss (4); HiTekRedNek (2); PWSlack (1); Rixter (1); SolarEagle (2); yesyen (1)

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