[PSUBS-MAILIST] Motor Issue

Tue Jul 20 16:24:32 EDT 2021

 James, Further thoughts.... Rick could be on to something with the bad connection on the positive. If it were giving intermitant power to the motor it could cause it to run rough & maybe the vibration from that is causing wear on the brushes and turning the oil black. I would check that it is not something in the motor controller. Maybe run it straight from a battery & see if it sounds better. The other thought was that I had heard of people adjusting the brush springs to give more pressure to avoid them lifting off their contacts due to the centrifical force of the oil lifting them. (as Emile mentioned) Possibly the simplest thing to do is drain the oil again and run (for a short time) & see if the noise goes. If it does maybe a lower viscosity oil will help. Good luck, Alan
    On Wednesday, July 21, 2021, 05:25:02 AM GMT+12, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 James, you mentioned that one of the two wires is getting hotter than normal and the first thing that came to mind was that it didn't have a solid connection somewhere? That may not explain the abnormal noise you said it is making but a bad connection will heat up a wire.Rick
On Mon, Jul 19, 2021 at 11:37 PM James Frankland via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Thanks Emile.  
This motor is definitly not right compared to the other two.  Im going to try Cliffs idea of adjusting the alignment.  Seems to be the only thing i can try, other than a new motor or air comp.
regardsJames

On Tue, 20 Jul 2021 at 08:44, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

All,

It is normal that a brushed oil filled motor runs not well in air. The brushes will float on the oil due to the higher RPM.

Emile

Van: Personal_Submersibles <personal_submersibles-bounces at psubs.org> Namens James Frankland via Personal_Submersibles
Verzonden: maandag 19 juli 2021 13:22
Aan: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Onderwerp: [PSUBS-MAILIST] Motor Issue

Hi All

Does anyone have any ideas on this?

Following the dive i did last week, i had a motor issue.  The motor did not actually stop or fail, but during the dives it just didnt feel right.

The positive wire going into the rotating penetrator would get hot after about 10 seconds of motor power.  I could also hear a kind of electrical noise from within somewhere.

So, the next day i took the motor apart.  The oil (Silicone oil) was VERY black.

I was expecting to see something had been rubbing, but i couldnt see anything.  It all looked fine.  

I put it all back together and it runs fine in air.  However, there does seem to be a louder motor running noise than the others.

I am unsure what the issue is.  My feeling is that its carbon in the oil, making it conducting and hence slightly shorting out, causing the heat on the cable.

The other motor cable did not get hot, nor did the oil go black.

Again, another video here.  https://www.youtube.com/watch?v=v_VxVfhM9t8&t=2s

Would appreciate any input.  Im not sure what to do.  Buy a new motor?  Air compensate it?

Many thanks
James

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