How to identify number of phases?

[AutoNub]

Hello. I look at various schematics all day long at work and I'm wondering, what is the fastest way to identify whether a particular system is 3 phase or 2 phase or single phase based on solely a schematic? They all seem to start with an A, B, C recepticle (3 lines).

Thanks!

 

[Raza]

Hi,
Can you upload a portion of the diagram where it says A,B and C lines for a better explanation on your RELATED diagram.

 

[AutoNub]

The above is a quick partial example...

 

[SherpaDoug]

That image shows Line (L1), Neutral (N1), and Ground (GND) so it is single phase.

 

[AutoNub]

If one of each is an indication of one phase, what would be an indication of multiple phases? Be specific.

Thanks.

 

[SherpaDoug]

If I saw L1, L2, L3, and GND I would expect 3 phase delta. L1, L2, L3 ,N1 and GND is likely 3 phase star. L1, L2 for 2 phase. N1 implies a power return. GND may conduct power if it is alone, or it is likely just for safety if it accompanies N1.

Note there are some 3 phase systems with one corner grounded, so it could only have L1, L2, and GND. You may find this in aircraft to reduce weight, but also in locomotives, ships, and anywhere poeple are too cheap to pay for decent copper.