Breakers overheating [RE-wrenches]

[Travis Creswell, Ozark Solar]

I'm not clearly seeing how the system set up.  I am assuming that the 100
amp panel (with main?) that William is referring to is fed by the generator
and the the inverters are treated as a load on that panel along with some
other generator only loads?  The inverters then feed another panel with the
remaining loads.  Is this set up as 120/240?

I have already deleted the original message (yeah I know I can go to topica
and find it) so I am going from memory.  I have numerous dual inverter set
ups with generators ranging from 5kW to over 20kW all set up as 120/240.  I
always take the batteries down and charge the system for hours at max charge
rate.  During the test I have every load in the house going and basically
take the system to it's design limits and then as far as I can go past.  I
have not burned up any breakers or experienced any nuisance trips during
these tests.

At grid only customers (no solar or generators) I rarely experience bad
breakers but I have seen loads fault after running at extended high currents
and essential burn the nub off the buss bar.  Breakers are inversely
proportional in how fast they trip.  That's why fuses are much better to
stop faults.  I had the Square D rep in my office this summer and he left me
a chart that showed how long the breaker takes to trip.  Extrapolating from
this tremendously difficult to read chart a 60 amp 2 pole QO breaker takes
nearly 17 minutes to trip at 120 amps.  At 5 times it's rated current it
takes 125 seconds or over two minutes to trip.

Is the stacking cable installed?  What about the power factor of the
inverters during charging.  I would assume something quite less than unity
but who has an idea.  Could the power factor be affected by undersized
battery cables?

Sorry to be of not much help

Travis
----------
>From: "Don Loweburg, Offline" <i2p at aol.com>
>To: RE-wrenches at topica.com
>Subject: Re: Breakers overheating [RE-wrenches]
>Date: Tue, Nov 14, 2000, 12:35 PM
>

>In a message dated 11/13/2000 12:38:41 PM Pacific Standard Time, 
>solar at eagle-access.net writes:
>
><< I had a breaker mysteriously burn up on a generator circuit.  A 4.5 KW gen 
>set
> burned up a 60 amp breaker.  No satisfactory explanation ever surfaced.
>  >>
>How about bad breaker. No reason to assume breakers can't be bad or defective.
>It is strange though. Failed breakers are not a big issue in my field 
>experience. Is this more common than I know?
>Don
>
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 michael.welch at homepower.com

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