Overcurrent on inverter

tnhunter
tnhunter Registered Users Posts: 13
I truly hope the expertise on the forum can help me with a serious problem with my off grid system.

I have an off grid system that I have had no problems with for the past seven years.

System consists of:

6 - BP3160 panels
4- ISOFOTON 150 panels
2- BP3170 panels
Trace - 4048 inverter
Outback - MX-60 charge controller
Trace - DC disconnect
16 - Trojan T-105 batteries

Problem is as follows:

The inverter is indicating an OVER CURRENT condition and shutting off. I went to the trouble shooting guide for the inverter and it tells me to check the AC wire system for shorts or miswired.

I did this discovered that it senses and overcurrent only when breaker number 6 or 15 in my AC panel is ON. I turned all the breakers off and when I turn either breaker number 6 or 15 on, the breaker does not trip, but in approximately 60 seconds the inverter senses and over current and shuts down, (this is with no loads on the circuit). No other breakers in the AC panel cause this to happen. I replaced the breakers in the panel, checked the wiring at all the outlets and can find nothing wrong with the system. This condition has started suddenly and as I said, there have been no problems for the past seven years and I am stumped.

Is it possible that one of two things have occured?

The inverter is defective?
Mice have damaged the wires on the AC side for these circuits?

Any advice would be greatly appreciated :confused::confused::confused:

Comments

  • arkieoscar
    arkieoscar Solar Expert Posts: 101 ✭✭
    Re: Overcurrent on inverter

    It sounds like it's a wiring problem. Can you monitor the inverter output and see if the load comes up slowly or spikes? I'm assuming you have an SW that can show the AC output on it's face.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Overcurrent on inverter

    It is typical for an inverter to fault off before a breaker trips in an over-current situation. They are more sensitive than breakers, and are measuring the full output load not just one circuit.

    Which leaves us with the question of why it's tripping if it didn't before. If only two circuits cause the problem, there's likely something wrong on those lines. Has any load been changed? Checking the wires (unpowered) for shorts/corrosion is a good idea, also if you have a clamp-on Ammeter you can see just how much current is being drawn.

    Another possibility: you're batteries are dying. I have to note you're a bit shy on panel for 450 Amp hours of battery. 1900 Watts total? That won't produce much charging current on a 48 Volt system. Maybe I've added them up wrong, but that is probably only capable of about 25 Amps into the batteries - barely over the 5% minimum. If that is the case, then 7 years could be end-of-life for those batteries. When a heavy load is applied, they may be dropping too much in Voltage and causing the inverter to shut down.

    Unfortunately it is also possible that the Trace inverter is breaking down. It's getting on in years too (aren't we all?), and may not be capable of its full output anymore.
  • tnhunter
    tnhunter Registered Users Posts: 13
    Re: Overcurrent on inverter

    That's one of the things puzzling to me. The batteries and relatively new, (16 months old). A back up generator charges the batteries anytime the monitored voltage falls below 48 volts for more than 2 minutes. The loads have not changed. The inverter will go into overcurrent when all the breakers in the panel are off except either one of the two breakers in question are on. They don't have to be on simualtaneously. If just one of them is on, then I get the overcurrent condition. Even with NO loads on either line, all lights off, nothing plugged in, in the middle of the night - overcurret!!.

    I have watched the AMP output on the inverter. Last night it was reading 2 amps output, no spikes, no gradual increase, just all at once the system shut down and the overcurrent light came on.

    I am going to check tonight for any possible shorts. I am really puzzled about this!!
  • McClary's Electrical
    McClary's Electrical Registered Users Posts: 21
    Re: Overcurrent on inverter

    I would meg the A/C branch circuits that are affecting this. It's possible the inverter is doing exactly as it is supposed to
  • Schmidt
    Schmidt Registered Users Posts: 12
    Re: Overcurrent on inverter
    tnhunter wrote: »
    I truly hope the expertise on the forum can help me with a serious problem with my off grid system.

    I have an off grid system that I have had no problems with for the past seven years.

    System consists of:

    6 - BP3160 panels
    4- ISOFOTON 150 panels
    2- BP3170 panels
    Trace - 4048 inverter
    Outback - MX-60 charge controller
    Trace - DC disconnect
    16 - Trojan T-105 batteries

    Problem is as follows:

    The inverter is indicating an OVER CURRENT condition and shutting off. I went to the trouble shooting guide for the inverter and it tells me to check the AC wire system for shorts or miswired.

    I did this discovered that it senses and overcurrent only when breaker number 6 or 15 in my AC panel is ON. I turned all the breakers off and when I turn either breaker number 6 or 15 on, the breaker does not trip, but in approximately 60 seconds the inverter senses and over current and shuts down, (this is with no loads on the circuit). No other breakers in the AC panel cause this to happen. I replaced the breakers in the panel, checked the wiring at all the outlets and can find nothing wrong with the system. This condition has started suddenly and as I said, there have been no problems for the past seven years and I am stumped.

    Is it possible that one of two things have occured?

    The inverter is defective?
    Mice have damaged the wires on the AC side for these circuits?

    Any advice would be greatly appreciated :confused::confused::confused:

    Certainly sound like a short within the circuit. I have seen this various times, were the breaker doesn't trip, but the inverter does go into AC overload. However, it has always been an external source (a load that is plugged into the circuit) and the cord / extension cord gets crimped, run over, etc. and causes a short.

    However, the circuit in the home could certainly be experiencing a short if the insulation has been compromised via a rodent or whatever.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Overcurrent on inverter

    Overcurrent on SW4048 is based on inverter branch or ACout branch within inverter. If off grid, on inverter it will be inverter branch.

    Set Menu 4 to "Inverter/Charger Amps AC" then kick in your problem breakers and watch readout. Since you say you have 60 seconds before inverter shuts down you should be able to read out how many amps the load is drawing. It will shut down between 33 and 35 amps of AC load on inverter.

    With just the inverter running (no gen) the menu 4 "Load Amps AC" should read the same number as "Inverter/Charger Amps AC".

    You need to know what breaker 6 or 15 is powering and their approximate amperage. You might have something that is shorting out in thoughs legs. The inverter will shut down before your breakers will trip if they have a momentary short.

    Next you can fire up your generator. If batteries are not charged, let them complete bulk cycle so the charging will not be loading generator. With fully charged battery nearly all the generator current will be going to ACout.

    Set Menu 4 to "Load Amps AC" and kick in your problem breakers. See what current is showing. Having the generator on, along with inverter supplimenting ACout will have much greater ACout (Load) current capability. You will see if the load exceeds 33 amps without causing inverter to shut down.

    Assuming you find the breaker 6 or 15 loads are not the problem, then you might be having a problem with the current sense circuit on the inverter branch where it is indicating a higher current then actually drawn.