3 phase connection

[xformer]

What will happen to 3phase source or load when the 3phase load Line 1 is connected to 3phase source Line2.

[joshnz]

Re: 3 phase connection

Well if the load is the only load on the source e.g transformer the unbalanced load causes magnetic flux to escape the core causing heating of the enclosure.
A motor connected in the way you described would not run and over heat.

I guess you mean like this.
---------------
------ \_-----
--------------

[xformer]

Re: 3 phase connection

so this is wrong phasing ,am I right?

[joshnz]

Re: 3 phase connection

Here is a clearer image.
Second image is wrong phasing.

[xformer]

Re: 3 phase connection

thanks for the clarification

[Marsman]

Re: 3 phase connection

In motor applications if you swap any two lines the motor direction will reverse. If you move all three lines (1->2 2->3 3->1) the motor direction will not be changed.

[kaboom]

Re: 3 phase connection

And if you have three single-phase loads supplied from a 3ph Y source, nothing will happen.

Take a few 277V T5s for example. Row 1-A, row 2-B, row 3-C. You can mix them up all you want, just make sure you don't smoke the neutral by putting two or more MWBC feeds on the same phase. That also applies to the 20A SABC(s) for resi kitchens, although with SP GFCI/AFCI bkrs, that won't work (anymore).


http://forums.mikeholt.com/showthread.php?t=132830

Saves repeating what's already been said.

-Paul

[joshnz]

Re: 3 phase connection

Thank's kaboom you helped me just confirm one of my theories about balancing for a long time I have wondered why the neutral/ground on the power distribution system could be small compared to the phases here the system is delta wye 230 400 / 240 415

[delaware74b]

Re: 3 phase connection

Kaboom - I've dealt with the aftermath of a 3-circuit, 277 volt (3-phase) lighting system where the neutral failed. Bear in mind, this was within a modular wiring system (read it as plug-and-play). 22 T5HO 4-lamp and 22 T5HO 2-lamp ballasts blew up, they didn't even bother to smoke

I'm guessing they didn't like the 480-volts due to no neutral.
The customer wasn't too happy with the bill for repairs with took 2 days to be fixed. They lost 1/3 of their lighting in the entire store from a single neutral failure.