[RE-wrenches] AC breakers used in DC applications

[bob]

Who was the inverter manufacturer? Please respond off list, I just had to
ask.

I would have sent it off list but it came as a bounced message.

 

Thanks,

Bob

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kurt
Albershardt
Sent: Sunday, May 16, 2010 6:14 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] AC breakers used in DC applications

 

Voltage is not the issue here, it is current, and battery fault currents can
be staggering - far more than one would ever encounter in a typical AC
system fed from a distribution transformer.  I have seen a 200A Class T fail
to act on an 48V inverter fault which resulted in welding the metal tabs of
the fuse holder (which had been greased with copper-laden Penetrox E) to
their sockets.  That indicates a fault current well north of 200,000 amps,
quite possibly sseveral times that.   A fire ensued, which triggered the gas
protection system and fortunately resulted in almost no peripheral damage.
It did cost about $10k to recharge and recertify the Inergen system.  The
inverter manufacturer was quite cagey on warranty replacement until they saw
the photos - at which point a replacement miraculously arrived by overnight
air.

 

 

 

On May 15, 2010, at 9:43 , Drake Chamberlin wrote:

 

I did see a QO breaker fail to trip on a 24 volt DC system with only battery
voltage behind it.  It burned a #12 wire completely in two.  




The 48v is a max rating not a nominal rating.
So yes only good for 12 and 24v systems.

However with CBI breakers I don't understand why the need for QO for DC
anymore?

jay

peltz power
On May 15, 2010, at 6:28 AM, Rebekah Hren wrote:

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer 
Office - 740-448-7328
Mobile - 740-856-9648 

 

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