Yes you are probably correct. I will try and test all components in that area to the best of my ability. So far I did not see anything that was shorted. That silicone type coating all over the board makes it difficult.
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Power-One solar Inverter driving me NUTS!!!
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the lamp circuit will be fine i guess . what i am trying to see is what turns it on and then see what tells it to come on . there must be something that measures the resistance to earth ground from panel outputs and i suspect something there is amiss . datasheet for the mcu might help a bit .
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Not sure which one is the MCU for this circuit. I do know the alarm relay is on this corner of the board. Do you think this might be the MCU? Sorry for the upside down pic. it’s the only way I can get it under my microscope.
edit: looks like that one is a USB to serial2 PhotosLast edited by mitsu2k; 11-23-2023, 02:30 PM.
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OK now I’m thinking there is really a ground fault. When I connected it back up to the array and turned it on, I tried to measure current from positive, DC, negative DC, to earth ground. I was not able to measure any current, but when on the positive and touching the earth ground with my probe, I noticed very slight arching. I don’t get this arcing on the negative side.
I don’t think that should be the case. When I measured for voltage between the positive terminal and earth ground, I get approximately 149 V. Between the negative and earth ground I get approximately 87 V. The array itself positive to negative measures approximately 256 V. When I disconnect the array from the inverter and just measure the positive and negative coming from the array to earth ground I get very low transient voltage, like 5 to 10 V.
but the question is, where could this leakage be?
edit: when I remove the 4 red MOVs and perform the above test again, I get practically no voltage from negative to earth ground but the voltage from positive to earth ground jumps up to about 191vLast edited by mitsu2k; 11-24-2023, 03:25 PM.
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Originally posted by petehall347 View Postleakage is on the negative if indeed there is any leakage .. the measurements suggest there is . maybe a cable is damaged or got water inside it .
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Originally posted by mitsu2k View PostOK now I’m thinking there is really a ground fault. When I connected it back up to the array and turned it on, I tried to measure current from positive, DC, negative DC, to earth ground. I was not able to measure any current, but when on the positive and touching the earth ground with my probe, I noticed very slight arching. I don’t get this arcing on the negative side.
I don’t think that should be the case. When I measured for voltage between the positive terminal and earth ground, I get approximately 149 V. Between the negative and earth ground I get approximately 87 V. The array itself positive to negative measures approximately 256 V. When I disconnect the array from the inverter and just measure the positive and negative coming from the array to earth ground I get very low transient voltage, like 5 to 10 V.
but the question is, where could this leakage be?
edit: when I remove the 4 red MOVs and perform the above test again, I get practically no voltage from negative to earth ground but the voltage from positive to earth ground jumps up to about 191v
i do have a document that comes with a different inverter that deals with this on the solar side.
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Originally posted by mitsu2k View PostI have a question about the MOVs. None of them look discolored or show any signs of heat. They test open with DMM. I know this is not a proper test but should I just not worry about these?
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Originally posted by CapLeaker View Post
best way to test MOVs is with the Megger, Put 250V or whatever their max rating is on there and if the Megger ranges out, they are good to go.
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I tested between the first and third legs in my photo. Here are the results.
500vdc test
#1
175 mOhms
#2
205 mOhms
#3
215 mOhms
#4
239 mOhms
I also tested the two blue ones on the AC side and those tested over 4000 mOhms. (full scale on megger)
Not sure what these results mean. Could all 4 of them be bad?Last edited by mitsu2k; 11-24-2023, 09:43 PM.
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