inverter overload question

squarebob
squarebob Registered Users Posts: 25 ✭✭✭
I have a circuit in my shop that is fed by a manual transfer switch. When I use grid power everything works fine. When I switch to my generator as the input everything works fine. When I unplug the generator and plug in the 2000W samlex pure sine inverter, the inverter just beeps and the overload light comes on . This is with nothing plugged into the circuit. Any ideas what is wrong? The inverter works just fine if I plug a load into the inverter and not go thru the transfer switch.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Assuming US home/wiring.... You have green wire ground, white wire grounded to green wire in main panel, and "hot wire" to 120 VAC (red or black) in main panel/outlet.

    My guess, some of the TSW inverters (I think some Samlex may have hardwired neutral to earth bond) have one wire already grounded (white wire neutral to green wire+case ground). If you have reversed the "AC hot" from the inverter and connected to the White (or green wire) of your AC panel wiring, you would have a dead short.

    Small gensets (call it around 3.5 kW or less), typically have full floating outputs (no white to green wire/case connection).

    If your AC inverter has a Green Wire to Neutral Bond, and you are only switching the "hot" (black or red), then you should disconnect the White wire to case bond in the inverter... There is a potential for "ground+white wire" ground loops in this case.

    If you switch both Black (hot) and White (neutral) wires to the AC inverter (and AC branch circuit), then you should not disconnect the White+Ground bond wire in the inverter.

    Note if you have a two pole switch, then my theory of hot/neutral/ground short would not be causing this problem you are seeing.

    In any case, double check the wiring/transfer switch/inverter connections and make sure they are correct.

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