3 Phase Inverters 1

[abc_poster]

Hi guys,

I've got a question regarding 3 phase grid-tied solar inverters without a neutral (3-wire type). How does a 3 phase inverter without a neutral supply power to single-phase loads? Since it doesn't have a return neutral to the inverter how does the circuit complete it's loop? I've got advice that it can't, which I don't quite understand. The reason being, if say L1 from the inverter is exporting power to the grid and L1 has a single-phase load on it, it would mean current would need to move from the grid to the load on L1 while L1 is also exporting. As the current can only move in 1 direction this naturally can't occur.
This makes me think that the inverter supplies power to the single-phase load and the excess gets exported out to the grid but how does the return path occur?

Hope this makes sense! Thanks in advance folks!

 

[itsmoked]

On that setup a single phase load is by definition a load between any TWO of the lines.

L1-L2 or L1-L3 or L2-L3 so there's your complete circuit.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

The grid supplies the neutral.
If the inverter is exporting balanced three phase power to the grid without a neutral, the grid can still supply line to neutral power because it does have a neutral.
Suppose that your inverter is exporting 30 Amps on each phase.
Your only load is 10 Amps line to neutral.
The current back on the grid will be 30 Amps, 30 Amps and (30 Amps - 10 Amps = 20 Amps.
The meter will measure the exported power based on the phase voltages and phase currents.


Bill
--------------------
"Why not the best?"
Jimmy Carter