Hi All,
When it comes to a whole house backup system, it occurred to me that since my house is two phase 240V, with the two phases balanced between the various circuits in my house (120V x 2 and 240 direct to the stove and dryer), that the power inverter would have to also provide two phase 240V to the transfer switch.
I am I correct?
I am also wondering how that would affect the inverter if the two legs were not balanced?
Am I missing something here?
-T
Yes. It's single phase 240vac. The 120 vac comes from a tap in the middle of the transformer windings. The tap splits the 240 vac in half.
This one is called single phase but the specs seem to indicate the output can be selected to suit < ? >
< but not 3 phase >
Hi Dean,
So 240v single phase to my house from the pole. I do not remember seeing a transformer anywhere on my property. What am I missing?
-T
A single transformer on the pole? The high voltage (power company) lines are buried in my immediate area. The transformers sit on the ground and are about half the size of an average chest freezer. My area has single and three phase power. There's an article here about three phase power that might show the difference. Phase is about timing.
Makes sense. Power is 240 until it hits a co-located transformer close to my house.
Seems to me a grid down inverter would have to do two phase to the transfer switch.
Calling the 2 hot legs " 2 phases " is what throws some people into apoplectic tantrums. because it's
2 taps off a single phase transformer ... Don't get lost in the terminology weeds. Your feed from the inverter needs to be like your feed from the grid - it's that simple. Your question about the inverter's capability to feed a possible load imbalance on your panel is valid - ask the inverter people. John T.
I do believe it is called a "center tap transformer". The two ends are 180 deg out of phase with each other.
This might help a bit with the phase thing. Farmers use three phase generators to power their center pivots. It takes time for the rotor to spin inside the outside windings even though it happens very quickly. The generators ideally spin at 1760 rpm. The three individual phases hit 0 at different times.
You need a 240V split phase inverter.
The transformer frequently isn't on your property, one transformer can serve several homes. With overhead line service they are typically on one of the nearby power poles.
All the solar/battery inverters I've seen (whole house and microinverters) produces 240VAC output which feeds directly into the entrance panel via a suitable size (in my case 30A) two-pole breaker.
The pole transformer here seems to be connected to 4 houses. The HV lines here are in the middle of the block and the pole is just across the fence in someone else's yard.
When we lived on the farm, there was only 1 house on the transformer.
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