19 Mar
2011
19 Mar
'11
12:47 p.m.
Brian Knittel wrote:
^^^^^^^^^^^^^^^^^^^^^^^^^
Isn't it more corret to say 'Otherwise the load is delta-connected and
can be conneted ot a delta-connected supply. You could also conenct it to
a star (Wye) supply of the appropriate phase to phase voltage by ignoring
the neutral ocnnection of the supply'.
Most computer systems that need 3 phase mains are star (Wye) connected,
simply because you can connect single-phase loads (of which there are
likely to be many) from one phase conductor to neutral.
I need to know how to determine if the setup
needs to be wye or delta.
Check the power plug or cable. If the equipment has a neutral (not
ground!) lead, it needs wye. Otherwise it needs delta.
That usually means that a four-lead power cable (three phases and
ground) for delta, and five-lead (three phases, neutral, and ground) for
wye. However, some old equipment doesn't have a ground lead, in which
case it is three for delta, four for wye.
If the equipment contains any three-phase synchronous motors, you have
to get the phases in the right sequence; if they are reversed, the
motors run backwards. That can affect blowers, and the spindle motors
of disk drives.
Murphy's law ensures that you will get this wrong the first time. If at
all possible, make sure that whatever the motor is drivbing will not be
damaged if it runs backwards 9remove drive belts, etc if necessary) and
poer up briefly to see which way it turns.
-tony