[RE-wrenches] CBI circuit breakers

[Kent Osterberg]

boB,

The Mitsubishi system is just two parallel strings.  The combiner was 
planned for future expansion.  It was last fall that I had trouble with 
those so I don't remember if they were "off" or "tripped".  The system 
with Evergreen panels is just three strings; it is possible but not 
likely that the problem is a fault in the array.  I found that breaker 
in the "off" position.  And that is strange, because it is really 
unlikely that anyone has been in the combiner box during the last year.

Kent


boB Gudgel wrote:
> Kent Osterberg wrote:
>> Allan,
>>
>> I've had trouble with breakers opening when they shouldn't.  On an 
>> array of two strings of Mitsubishi 175s (Isc = 7.9A) I had two 15-A 
>> breakers open.  Last week, I had a low-power call from a customer 
>> with three strings of Evergreen 190s (Isc = 7.1A); one 15-A breaker 
>> in the combiner was open.  Most of my installs are around 3000 ft 
>> elevation, so the irradiance is possibly a little higher than normal, 
>> but not by enough that it should be an issue for 15-amp breakers.  If 
>> this is a wide-spread problem, I'd expect others on this list to have 
>> noticed.
>
> Hi Kent,
>
> Could there be a defective module and the breaker is just doing what 
> it is supposed to do ??  What is the series fuse rating for those
> modules ?  (probably 15A?)   A shorted or defective module would cause 
> those other strings to make it trip, if there are enough
> parallel strings.   I hope there isn't some kind of intermittent 
> problem...
>
> Was the breaker actually in the "tripped" position or the "off" 
> position, since there is a difference?  (tripped of course means
> that there is some play in the lever.)
>
> We (and OB) have sold literally over a million (or millions?) of these 
> breakers and we just haven't seen any problems.  You have been
> using these breakers for years now...   Have you seen problems before 
> this ??   I understand that any problems with CBI breakers
> have been AC breakers, not DC, and even then, problems have been far 
> and few between.
>
> You could test the breakers though...   Just shove, say, 10 Amps 
> through one of the questionable breakers and see if it trips after a 
> while.
>
> It seems kind of odd that more than one of these breakers would have 
> defectively tripped near the same time ( week ?  day?  week-day?).
>
> There is, I suppose, the possibility that they could all of a sudden 
> have started having some kind of problem, but CBI breakers have
> had an excellent track record for many years  now.  We haven't heard 
> anything from any other customers here at MidNite.
>
> Can't wait to hear what's causing this problem though...  I'm sure it 
> will be very interesting !
>
> boB
>
>
>
>>
>> As others have mentioned, it is important to take precautions to make 
>> sure that stranded wires are well tightened in these breakers.  I 
>> tighten, wiggle, re-tighten, and then check again later.  On systems 
>> where I've had breakers open, loose connections haven't been the issue.
>>
>> Kent Osterberg
>> Blue Mountain Solar, Inc.
>> www.bluemoutainsolar.com <http://www.bluemoutainsolar.com/>
>>
>>
>> Allan Sindelar wrote:
>>> I have had no problems to date, Kent. Can you be more specific as to 
>>> what
>>> problems you have had?
>>> Allan Sindelar
>>> Allan at positiveenergysolar.com
>>> NABCEP Certified Photovoltaic Installer
>>> EE98J Journeyman Electrician
>>> Positive Energy, Inc.
>>> 3201 Calle Marie
>>> Santa Fe, New Mexico 87507
>>> 505 424-1112
>>> www.positiveenergysolar.com
>>>
>>> -----Original Message-----
>>> Is it just me, or have other wrenches had problems with the CBI 
>>> circuit breakers used in the Outback or Midnite combiner boxes?
>>>
>>> Kent Osterberg
>>> Blue Mountain Solar, Inc.
>>> http://www.bluemountainsolar.com/
>>>