Author Topic: tripping of DC circuit breaker  (Read 599 times)


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tripping of DC circuit breaker
« on: March 20, 2017, 04:31:00 PM »
I have a small 300 watt solar system/ 12V with a 700 watt inverter ( using it as a separate back up for power outages). I installed a 15 Amp/150V midnite solar DC circuit breaker between my charge controller and battery bank ( 2 x 100Ah/12V each connected in parallel).
After using the installation for almost 8 months i notice the past days that the breaker keeps jumping off each time i turn the inverter on for use.
I have changed the breaker from 15A to 30 Amps, but i get the same problem.
Does someone have advice for me please?

Thank you


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Re: tripping of DC circuit breaker
« Reply #1 on: March 20, 2017, 05:37:45 PM »
If you can do a sketch of all the wiring from PV to CC to battery to inverter it would help or post a few pics with a description of what we are looking at will assist in diagnosing...hth
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Re: tripping of DC circuit breaker
« Reply #2 on: March 20, 2017, 05:57:09 PM »
You should be able to figure this out by yourself with a minimum of detective work.
A breaker only opens when the current through it exceeds the breaker rating.
A big clue as to why this is happening is because when you power up the inverter it needs about 60 amps of current. Even if you have no AC loads connected to it, it may need to charge some grunty(ish) input stage caps so have a large inrush current at power on time.
So does it look likely that a large proportion or maybe all of this possible 60 amps is trying to flow through the breaker?
All wires/cables to everything nice and tight? inc battery interconnects?
Is the inverter connected direct to the battery bank via its own 80 to 120 amp breaker?
If not why not?
Please let us know how you resolved this problem
« Last Edit: March 20, 2017, 07:23:52 PM by dgd »
Classic 250, 150,  20 140w, 6 250w PVs, 2Kw turbine, MN ac Clipper, Epanel/MNdc, Trace SW3024E (1997), Century 1050Ah 24V FLA (1999). Arduino power monitoring and web server.  Off grid since 4/2000
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Re: tripping of DC circuit breaker
« Reply #3 on: March 21, 2017, 02:00:30 PM »
Van, it ~could~ possibly be that the charge controller's positive line is electrically connected
too close to the inverters' positive line and not close enough to the battery.

What can happen is that the inverter turning on draws more temporary current
from the charge controller from the battery.

Another idea is that the resistance from the battery is higher than it used to be
and could be forcing the inverter to draw more current from the CC than it used to.

It might be a combination of the two ?  You might try an experiment and pull
the CC positive line from its circuit breaker and wire it more directly to the
battery positive.

Actually, BOTH positive and negative from the CC is the best but trying this
with just the positive might be worth a try to see if it helps.