Determine phase rotation from one line diagram
Determine phase rotation from one line diagram
(OP)
We are having a discussion about determining phase rotation of a generator from a one line diagram. The drawing in question has a rotation arrow moving in the counterclock wise direction. It also has phase indications of T1 @ 12'oclock, T2 @ 4 o'clock and T3 @ 8 o'clock. The opinion here is ABC rotation.






RE: Determine phase rotation from one line diagram
RE: Determine phase rotation from one line diagram
RE: Determine phase rotation from one line diagram
The drawing does not indicate what is connected to T1 T2 or T3. But the way I interpet it, if C phase is connected to T1 and B phase to T2 and A phase to T3 then the phasing would be CBA or ABC if connected 123.
RE: Determine phase rotation from one line diagram
RE: Determine phase rotation from one line diagram
That way there is no mistakes.
JTK
RE: Determine phase rotation from one line diagram
I like GE's statement - "The voltages reach a positive maximum in the order T1, T2, T3." No confusion on CCW or CW, viewed from turbine end or collector end. But I have had generator drawings showing "ABC, T1, T2, T3 rotation" where the gas turbine spun the rotor in the opposite direction from "standard" so the electrical drawing (and my buswork) was wrong.
Another drawing detail that is useful is a view looking at the generator terminals saying something like "Viewing the bus leads as they exit the terminal enclosure, the phase sequence is T1, T2, T3, right, center, left."
RE: Determine phase rotation from one line diagram
The labeling T1 T2 T3 will not tell you where ABC is located it only tells you the sequence in which the phases appear, there are only two. 123 or 132. The three phase generator can be sychronized with T1 connected to A B or C as long as the remaining two phases follow the proper sequence. The reason that all your drawings show phase A connected to particular terminal is because the synchronizing pot is permanently wired to a given phase and it always synchronizes to that phase.