bridge rectifier

[chainsaw]

I use a dual rotor "Hugh" design in a small micro-hydro situation. Output is usually in the 125 watt range. When first installed after several weeks I noticed "fuzz" growing on all the bridge rectifier terminals.  I ran a ground wire from the unit to a large metal culvert, this stopped the "fuzz" growing.  On a regular basis of 12 to 18 months the terminal on one or more of the rectifiers will separate  where it exits the bedding epoxy.

It's not vibration related but appears to be corrosion.  Has anyone seen this type of issue and any ideas on correcting will be welcome.

Thanks

[TomW]

I am no expert but I suspect corrosion. If so you can simply coat the connections in grease to keep the air off that should eliminate most of the corrosion issues since air is necessary for oxidation, well oxygen.

Are the batteries in the same space?

I ask because batteries produce corrosive gasses when charging. If so, the real fix is ventilation but the grease trick will work, too.

Tom

[chainsaw]

Tom

Thanks for the reply. The batteries are located approx. 300 feet away from the hydro.

It seems to be the same terminal on the rectifiers that corrode. This is what has me confused (doesn't take much) since it is the same terminal that breaks.

The other three terminals are sound with no sign of corrosion.

[Rover]

Are your leads or connectors dissimilar metals ? I know its a long shot , but never know

[hydrosun]

My guess is there is some electron flow to ground from the positive terminal.  In the moist atmosphere of the hydro there is some current leakage from positive to the ground. That may cause some electroplating of the positive terminal material to elsewhere. Keeping the terminal dry or sealing it with grease should stop that.
 I've never seen it done that quickly, so I suspect that you may have minerals in the water that aid in the water conductivity.
Chris

[chainsaw]

Looks as if I need to do a better job with corrosion
protection.

Hadn't thought about the minerals in the water.

Thanks

[ghurd]

'Grease' could be phrased differently.
'Owl Poop'?  'G-B Ox Guard' (TM)?
Ask for a little tube at the hardware store.   $4?

Strange situation.
Might have galvanic reactions (that's what Chris said).
Might find related info regarding bridges (the kind that go over water).

I have a feeling it is a galvanic reaction, somehow related to bad wire.
The 300' run is not done with automotive grade wire, or 'outdoor rated' extension cords, is it?
G-

[chainsaw]

The wire run from Hydro to batteries is #10 rated for underground service.  I might add that on occasion I would spray these  terminals with electrical contact cleaner, I never could determine whether this was good or bad for the corrosion problem.  I will do as all have suggested and use electrical grease.