Diode failure

[powerhouse1]

Hi all,Ihave been running a 10 foot mill for about 3 years burnt out one stator made some changes now seems ok now .Imade a bigger one to get more power on calmer days,Ikeep it turned off until it is needed because the two together make over   50amps in not to much breeze ,but now and again it stops it is adiode stoped working ,I use 3no 50amp diode bridge ,usulya diferent one each time.The rectifier as at bottom of the tower and battrie bank is a 20m run away,the wire is heavy underground about 3 mill thick +&-.would be graitful for any advise thanks.

[dnix71]

Diode bridge? If this is a full-wave bridge, many have a metal base you can grease and heat sink, and a center hole to bolt it to the heat sink.

[powerhouse1]

The diode bridge is on a big heatsink, and out in open air, just sheltered from the rain. Will ordenary greese work?.thanks for your comments.

[dnix71]

No. Radio Shack sells small tubes of heat sink grease. Any decent computer shop would have it, too. You don't need the "silicone free" stuff, but it wouldn't hurt. The silicone-free stuff is for electronics and computers. Don't use the peel and stick heat sink pads. They don't do nearly as well.

You might take a new diode bridge to a local conputer shop and have them size and mount a heat-sink with a fan from a scrapped cpu. The fans usually run on 12v dc and there are some that use very little power.

If you keep blowing bridges then you need a bigger bridge. Maybe instead of a full-wave bridge, get oversized diodes and build your own bridge.

[GLC]

If your diode is heating up while on a heatsink already, it's time for a new heatsink. Get a pure copper heatsink. They draw the heat and disapate it pretty quickly. Most copper heatsinks in pcs really don't need a fan but they put them on anyway. Something like this one from newegg should work real good. Also get yourself some artic silver heatsink compound and your heat problems should disappear. I know you said you had a heatsink but...

 http://www.newegg.com/Product/Product.aspx?Item=N82E16835114084&cm_re=copper_heatsink-_-35-114-0
84-_-Product

[powerhouse1]

I was makeing very little power all week, snow and frost and very little wind,now that the thaw has started the wind is back again, just a light breeze,i am keeping close watch on things today.The heatzink is just warm the heat seems to be at lugs were spades are pushed on maby i need to solder the wires on. Mite just be a weakpoint.Thanks for coments and picture looks like a grait heatzink.