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 BillyD 05-13-2008 06:44 PM

Generator reconnect

When looking at a 3 phase generator wiring diagram to switch from 3ph to 2ph its shows L1, L2 and LO. Anyone know what LO means. I know L1 and L2 is line 1 and line 2 but LO??????
Thanks

 Speedy Petey 05-13-2008 07:00 PM

L0 is the neutral.
And it's NOT 2-phase. It's single-phase.

 micromind 05-13-2008 11:11 PM

If this is a 3 phase generator, and you're using L1, L2, and LO (not L3), and it's connected low wye, you'll have 120/208 single phase power. It's not true 120/240, like in your house, but for all practical purposes, it'll work just fine. Assuming the two legs are balanced, it'll only operate at 2/3 capacity.

If it's 12 lead, it can be re-connected double-delta or zig-zag and deliver true 120/240 single phase power at 100% capacity. If it's 6 lead, only the zig-zag will work. If it's 4 lead or 10 lead, it cannot be connected for 120/240, only 120/208, and reduced capacity.

The connection you choose will depend largely on what it's being used for.

Rob

 BillyD 05-14-2008 06:17 AM

2 Phase

1 Attachment(s)
I am no master electrician but I believe you are incorrect about the 1 phase. Single phase is just that, 2 phases is 220 house current using 2 120 degrees out of phase lines from the generator.
Please correct me if I am wrong but see the attached article and sinwave.
Thanks
Billy

 Silk 05-14-2008 08:28 AM

Quote:
 Originally Posted by BillyD (Post 123102) I am no master electrician but I believe you are incorrect about the 1 phase. Single phase is just that, 2 phases is 220 house current using 2 120 degrees out of phase lines from the generator. Please correct me if I am wrong but see the attached article and sinwave. Thanks Billy
You are wrong. Look at it this way, 3 phase has 3 wires associated with it (we will forget about the neutral for now) labeled A, B, and C.

1 of the phases is between the wires A and B

The second phase is between wires B and C

The third phase is between wires C and A

So using any 2 wires will give you single phase

now if we use A and B for a phase, we would connect a neutral right to the middle of that phase, ground it so we have a zero reference point, and we now have single phase with 120 to ground from A to N, 120 to ground between B and N, and 240 between A and B.

 joed 05-14-2008 08:41 AM

Quote:
 Originally Posted by BillyD (Post 123102) I am no master electrician but I believe you are incorrect about the 1 phase. Single phase is just that, 2 phases is 220 house current using 2 120 degrees out of phase lines from the generator. Please correct me if I am wrong but see the attached article and sinwave. Thanks Billy
You are wrong. In your house you only use one phase that is center tapped. It is one big multiwire branch circuit.

 jrclen 05-14-2008 09:35 AM

Quote:
 Originally Posted by BillyD (Post 123102) I am no master electrician but I believe you are incorrect about the 1 phase. Single phase is just that, 2 phases is 220 house current using 2 120 degrees out of phase lines from the generator. Please correct me if I am wrong but see the attached article and sinwave. Thanks Billy
You have the three phase part right, but the 240V house power wrong. It's all in the transformers. For a typical residential service, the transformer consists of two windings, the primary is a single winding, just a single coil of wire. The secondary is also a single winding, a coil of wire, but with a tap in the center of the winding. That tap remains at 0 volts and provides the neutral. The ends of the secondary are at opposite polarity with each other. At 240 volt potential. Not phase, but polarity. They are 180 degrees apart, not 120 as in three phase.

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