Question about generating split phase power

[hapster57]

in a split phase transformer, how is the neutral wire shared. since the split phases of the hot wired are 180 apart, what happens in the neutral wire. my question stems from having two single phase inverters and wanting to hook them up to a home panel board with a common neutral the two inverters will be randomly out of phase with each other, but can they share the neutral wire?

 

[Baluncore]

In theory, yes, but there will be problems, and traps for the beginner.
A couple of which might be;

1. You will be unable to run equipment at double voltage from the two hot wires, since the unknown phase drift will make it a low frequency.

2. The neutral wire will at some times have only half the section required. You would have to halve the power drawn from each of the hot wires. That is because the current in the neutral from the two hot separate wire circuits do not cancel in phase like normal.

This is a dangerous game. I recommend you avoid it.
If you don't know what you are doing, call a local electrician.

 

[hapster57]

I didn't think it possible to use a common neutral for out of phase power sources,vbut I'm just not grasping in a standard split phase transformer what happens in the neutral wire and why that works

 

[Baluncore]

It works because
the current in hot1 that returns through the neutral is out of phase with
the current in hot2 that returns through the neutral, so the two opposite currents in the neutral cancel.
If both hot circuits have a maximum resistive load, then there is no neutral current.

 

[hapster57]

It works because
the current in hot1 that returns through the neutral is out of phase with
the current in hot2 that returns through the neutral, so the two opposite currents in the neutral cancel.
If both hot circuits have a maximum resistive load, then there is no neutral current.

I see what you are saying, that worst case, if L1 had 10 amps and L2 had 20 amps, the neutral wire might possibly have to carry all 30 amps as opposed to a split phase transformer neutral only carrying the difference of 10 amps. Thanks.

 

[Dullard]

For the transformer, the neutral is effectively just a center-tap of a single winding (the 'ends' of the winding are the 2 'phases.'

Assuming that the inverters are completely 'floating,' you could theoretically share the neutral. This 'shared' conductor would have to be sized to carry the full current (sum) of both inverters. Your house probably isn't wired this way - DON'T!

 

[berkeman]

my question stems from having two single phase inverters and wanting to hook them up to a home panel board with a common neutral the two inverters will be randomly out of phase with each other,

This is a dangerous game. I recommend you avoid it.
If you don't know what you are doing, call a local electrician.

Your house probably isn't wired this way - DON'T!

This is indeed a dangerous question from an inexperienced person. @hapster57 -- please do not do this. It is dangerous, against your local building codes, and puts you and your family at risk for fire. If you want to generate split phase power from an inverter, there are other ways to do that and be within your local building codes. Please do contact a local electrician with your questions.

Thread is closed.