Onan LTC Series - Page 14

CHECKING
PHASE
RELATIONS OF
A
3.PHASE
STANDBY
Phase relationships
determine the
direction of rotation
of
any
3-phase
motor.
Phase
relations
must
be correct
if
motors
are to rotate in the
proper
direction under both
normal
and emergency
power.
Always check
phase
relation-
ship
as
follows before
operating generator or
connecting
line
to load.
Connect
a lphase motor to the load
terminals
(and
power
to the
line
side
of the transfer
switch)
and
check motor
rotation.
If
the
direction of
rotation
is
correct, the
lines
phase
relationship
is
correct.
If it rotates
in
the wrong
direction, change
the direction of rotation
by
reversing
any
two of
the three main
phase
leads
connected
on
the transfer
switch line-side.
Next, turn
off
the
main
power,
start
the
generator
and
check
motor
rotation
when
powered
by the
generator.
If
the
direction
of rotation
is
wrong,
conect
it
by
reversing any
two of the three main
phase
leads on
the
generator
(GEN)
side of the transfer switch.
THREE.PHASE
SERVICE
AND A SINGLE-PHASE
STANDBY
In some
cases,
emergency
singleahase loads
connected
from one leg
to
ground
of
a
4-wire .lphase service
can be
protected
by
a
singlephase generating
plant
and load
transfer
control. This
is
often
done
in institutions
where
all emergency
lights
are connected from
one
l"g
of the
4wire
service
to
ground.
The load transfer
control
used
for
this
service should
be wired
to the
generating plant
with
the
leg of
the commercial
power
to
be
protected
by
stand-by
power
connected
to the
line
side
of the transfer
switch.
Wiring this type of conhol can become
a complicated
pro
cedure,
depending
on the
electrical
service, the
problems
of
Sphase
balance, and
a knowledge
of
the
loads to be
operated
during
a
power
failure.
It should
be attempted
only
with a thorough knowledge
of
the buildings
electrical
service. If
questions
arise
conceming,
the use
or installation
of
a
control in
this type of
service,
contact
Onan
furnishing
full informatiur.