On 1/23/2011 10:54 AM, lid wrote:
On Sun, 23 Jan 2011 09:09:01 -0600, The Daring Dufas
wrote:

On 1/23/2011 7:51 AM, RBM wrote:
"Dean wrote in message
...
The Daring Dufas wrote:

When I install 3 phase refrigeration or HVAC equipment, I also install or
order the factory option of a 3 phase protection module which shuts
down the control voltage if there is any problem with the power. The
cheap simple unit doesn't care about which direction a motor is turning
in relation to incoming power but there is a more elaborate unit that I
install on high end gear that will not operate if the 3 phase is not
exactly L1 L2 L3 as seen on an oscilloscope.

TDD

Do you ever use anything like this Amprobe phase tester?
http://tinyurl.com/4ukhq4b


Years ago we use to have a mechanical phase tester. We were supposed to use
it when connecting 3 phase service equipment. When connecting a 3 phase
motor, it doesn't help to know the phase rotation of the power supply, but
not know the phase rotation of the motor leads. Ultimately, trial and error
is probably the quickest method



I use my phase tester even when the power company crew is there hooking
up the drop. The linemen around here are OK with it and will make sure
the sequence is right before making a permanent connection. Southern
Company Power wires L2 as the high leg in a Wye secondary 3 phase. If
I'm lucky, I can get Delta-Delta then everybody's happy. :-)

The secondary is a delta if it has a high leg. A wye will have equal
voltage on each leg with respect to the grounded conductor.

DOAH! I stand corrected. I should have said center tapped delta has the
high leg. I was reading my diagrams wrong and I don't even use
recreational drugs. I got it mixed up. :-)

TDD