DC250 HUMMMMMM [RE-wrenches]

[Travis Creswell]

John,

I often hear AC breakers humming under large loads but I have not heard a
hum from the DC250.  I'm guessing it's inductance related to the distance
from of the run.

Travis Creswell
Ozark Solar
----------
>From: cvsolar at aol.com
>To: RE-wrenches at topica.com
>Subject: DC250 HUMMMMMM [RE-wrenches]
>Date: Sat, Apr 22, 2000, 3:12 PM
>

>Hi wrenches,
>   I recently upgraded my own home system with a Trace DC250 Dicconnect Box 
>to replace the old fuse from years ago and now have strange noises coming 
>from the box.  I get a variable pitch whine when the wind turbine is cranking 
>(BWC1500) and otherwise have what appears to be a 60 cycle hum similar to a 
>transformer when the inverter is loaded.  The only thing different between 
>this setup and all the others I have done for customers is that the 4/0 
>cables to the inverter are quite long at about 12' each (taped together to 
>eliminate inductance) and also the DC250 is on a wall opposite the battery 
>bank and I ran the plus wire out the lower left-hand knockout and thru the 
>wall to the battery and the minus wire out the lower right knockout and thru 
>the wall on that side to the batteries.  This does cause considerable 
>distance between the cables (4/0).  Is this some kind of an inductive 
>feedback?  Can I damage the inverter?  
>
>On another note.  The problem customer I wrote about a while ago who wanted 
>me to take the system back out is now happy with it.  He finally dropped his 
>mental block to learning how it works and now likes what he has learned!   We 
>are still dealing with a generator that is too small (an old 2000 watt 4 
>cylinder Kohler.  It does run sweet and sips fuel lightly but I had to 
>program the SW4024 to start it at 85% and run until the batteries are full to 
>keep a good reserve for his huge loads.  The generator often cannot run the 
>house and the inverter has to assist.  It has been quite a learning 
>experience at carefully programming to be one step ahead in a bad situation.  
>If the high autostart setpoints don't work, then he has agreed to sell the 
>Kohler and buy a bigger generator.
>
>Let me know if anyone has had a humming Box.
>
>John Blittersdorf
>Central Vermont Solar and Wind
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_________________________________________________________
Enlighten your in-box.         http://www.topica.com/t/15