63A Breaker is Tripping Under Low Load

[Alaska Man]

The breaker works fine while the PV's are putting 50+ amps through it. It's hot, the wire is hot, but it's not tripping.

The Breaker is tripping in the morning under low-light conditions, probably about the time the Classic wakes up. Any thoughts?

This breaker is between the controller and the battery

[mahendra]

did you check that the connections are tight/or maybe your voc of your panels.
In the morning the voc can be pretty high,before the classics actually starts to produce real power.
If its a midnite 63 amp breaker it would be rated for 150v max.

[mahendra]

noticed you did not mention how your array is wired and the specs of your panels.

[mahendra]

you did not mention what type of breaker this is din rail /panel mount .If i am correct midnite recommend the panel mount type of breakers of cc to battery .Just suggestions that you can use.

[mahendra]

you should also check all connections including grounding i have had a few trips while i worked on one of my two classic before.Causes were as simple as grounding wire /battery wire that was not connected to the functioning classic(classic that was still on ,battery cable and ground from the classic work was done on which was off).

[Alaska Man]

I'll check it out and make sure things are snug.

63A dinrail mounted breaker. (2) 230W panels in series in each array, then parallel at the combiner box.

Max Voltage now is about 77V

The Classic and the arrays are grounded to one ground rod. The battery bank/inverter/charger/distribution panel are grounded in another spot. We are on an Ice-Lense/Perma-Frost up here. So grounding can be an issue. Most people run the grounding wire on the surface under the house for 20' or so, as did I.

[vtmaps]

The Classic and the arrays are grounded to one ground rod. The battery bank/inverter/charger/distribution panel are grounded in another spot.

I'm confused... How far is the classic from the battery?  In most systems they are close enough together that they wouldn't have separate ground rods.

In any case, your grounding is a problem, if not the problem.  You need to have single point grounding.  In some systems, depending on the distances involved, you may need two ground rods, but they should be bonded together.

In order for safety grounding to be effective, the resistance between the various equipment grounds must be very very low (like copper).  You don't need a good connection to earth for safety grounding.   However, a low impedance connection to the earth is necessary for lightning protection.

--vtMaps

[inetdog]

In the morning, as stated, the Voc and Vmp of the panels will be at their highest, but the current from the panels will still be limited to no more than Isc, which will be slightly lower than the normal temp Isc.
There is no way that the CC can force the panels to produce more than Isc.
But if the 50A you mention is Imp, then I suppose that the higher Isc value could be drawn at some point during the initial CC startup and maybe full range MPPT characterization. That just might be enough to trip the breaker.

[dgd]

The breaker works fine while the PV's are putting 50+ amps through it. It's hot, the wire is hot, but it's not tripping.

There is no way that the breaker or wire should ever be getting hot. This is a big problem and there is resistance where there should not be any.
if you have checked all the wiring is nice and tight and its still hot then I suggest you change breaker for another and the wiring between breaker and battery and breaker and controller preferably with a larger size (smaller guage).

dgd

[TomW]

The breaker works fine while the PV's are putting 50+ amps through it. It's hot, the wire is hot, but it's not tripping.

There is no way that the breaker or wire should ever be getting hot. This is a big problem and there is resistance where there should not be any.
if you have checked all the wiring is nice and tight and its still hot then I suggest you change breaker for another and the wiring between breaker and battery and breaker and controller preferably with a larger size (smaller guage).

dgd

I must strongly agree with DGD here. Any heat in wires or breakers is not good. The meaning of hot adds some windage to the scenario, also. I would swap out the breaker as a start. Actually I would use my IR thermometer to narrow down where heat was coming from and give the wiring a good close look. Heat is lost power but more important enough of it can and will kill electronics and burn things.

Just my 2 bits worth.

Tom

[Alaska Man]

The breaker works fine while the PV's are putting 50+ amps through it. It's hot, the wire is hot, but it's not tripping.

There is no way that the breaker or wire should ever be getting hot. This is a big problem and there is resistance where there should not be any.
if you have checked all the wiring is nice and tight and its still hot then I suggest you change breaker for another and the wiring between breaker and battery and breaker and controller preferably with a larger size (smaller guage).




dgd

That's what my plan is. I was directed to use 6ga, at the time I had the panels in series. Now that they are 2 string in parallel and the amperage has increased I thought that I should go with 4ga. The run from the controller to the battery bank is about 6' to the positive about 3' to the negative. Going to go with an 80 amp breaker also.

But the tripping does not seem to be power related. All connections are good so I will focus on the ground and bond the two grounds as suggested.

Thanks.


Does anyone know anything about the Air Marine 400 watt wind generator? There is one for sale on Craig's List for $350. It's still in the box.

[zoneblue]

Wire size can be counter intuitive. If you change from two series panels to two parallel panels:
- V halves, I doubles
- P loss in cable is proportional to I squared.
- therefore P loss becomes 4 times greater for the same cable.

Then you have the interesting AWG system, which is also non-linear.
- Each 3 AWG guages is double the cross sectional area.
- Thus 2 times bigger than 6 guage is 3 guage,
- and 4 times bigger is 0 guage.

Of course, we dont know how well specced the original cable was, so just use the vdrop calcultor to confirm the correct guage.

That's what my plan is. I was directed to use 6ga, at the time I had the panels in series. Now that they are 2 string in parallel and the amperage has increased I thought that I should go with 4ga.

[Alaska Man]

Thanks, I found a cool calculator here: http://www.powerstream.com/Wire_Size.htm

It looks like with a run of 5' (round trip) 4AWG will keep my loss under 2% at 90A. 

[zoneblue]

Still doesnt smell right. 4 guage, 90A.. NEC Ampacity for 4 guage is 70 / 85 / 95 A depending on insulation type. Generally if youre near the ampacity, thats not good.

4 guage is what is used from the classic because bigger wont fit (its not ideal), but it generally only runs _inches_ to the disconnnect, and from there onto much fatter cable to the battery. It is quite important to have no measureable voltage drop between the classic and the bank, because that will confuse the charge setpoints. Say you have half a volt being lost, then absorb will start half a volt too low. Etc.

I think you had better head on over to NAWs and get Bill and Coot to take a once over your system.

[Alaska Man]

This is from another one, both are pretty close.

Voltage Drop Calculator
Results:
Voltage drop: 0.22
Voltage drop percentage: 1.83%
Voltage at the end: 11.78

960W array/12 Volt system, 150 Classic Controller is 4' from the postive 2' from the negative.

Right now I push 77A max from the Array. The controller is normaly reading 50-55 amps at 600w-700w. I used 90A to be conservative.

Exsisting panels:

VOC 36.7
Max Power Volt 29.7V
Current Max Power 7.74A
Max System Voltage 1000V/600V
Max series fuse rating is 15A


Panels (2) 2 panel strings in series, parallel at the combiner.