Help hooking up a Trace Engineering SW4024 to the grid

lerdmanlerdman Registered Users Posts: 1
A friend of mine bought a cabin that has a very nicely installed and well maintained system that includes a Trace Engineering SW4024 inverter/charger. He has recently connected to the grid and we've reprogrammed the unit to operate in Low Battery Transfer (LBX) mode and after completing all of the recommended settings, we switched on the 60A breaker from the grid to the unit's AC1 input. The AC1 light went to a blinking green to tell us it saw AC voltage there, but it would not synchronize or go to line-tie. We waited and finally looked at the AC1 voltage on the User Menu->Meters->AC 1 Voltage. It drifts from 84 VAC to around 124 VAC and back down. It never synchronizes. We have confirmed that the grid is delivering 120 VAC +- 2 VAC.

I see in the manual that there is a jumper (J4) that according to the manual:
AC1 RELAY (Red) LED Allows visual indication of AC1 relay operation. The LED will be on when the AC1 relay is closed (engaged). This LED along with the test-jumper adjacent to the LED is used by utilities to perform voltage and frequency tests to qualify the SW Series Inverter/Charger for line-tie applications.

but there are no other details about whether or not the jumper should be in place for normal operation or removed. Any advice please?

Many thanks,


  • BB.BB. Super Moderators, Administrators Posts: 30,520 admin
    It sounds like a connector (board to board, ribbon connector) or something like a transformer/voltage divider is making a poor connection. I have fixed a lot of other electronics by simply (turning off and) unplugging/reconnecting connectors (even pulling jumpers and putting them back).

    That is a really old AC inverter and finding somebody to repair it may be an issue... And there is always the question if it is worth repairing (plus shipping, old unit and something else may fail later). Here is a post with several companies that repair inverters:

    Regarding the jumper--If all else fails, I would probably try changing its position and see what happens.

    Are they going to keep the inverter+batteries+solar as backup power? Or once the repairs (inverter, battery replacement, etc.) get too much--Will they decommission the system?

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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