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A
PD MANUAL
IOM-39
17 of 36
Aug 99 R1
To
calculate
voltage
imbalance
(NEMA
method)
refer
to
the
following
example:
Phase
to
phase
voltage
readings:
235V
236V
230V
The
average
Voltage
between
legs
is
(235+236+230)/3
=
233.7V
Highest
voltage
deviation
from
average
is:
233.7V
–
230V
=
3.7V
Voltage
imbalance
percentage
=
Highest
deviation
divided
by
average
X
100
3.7
/
233.7
x
100
=
1.6%
This
imbalance
is
less
than
2%
and
therefore
is
OK
If
voltage
imbalance
is
greater
than
two
percent
(2%),
turn
off
main
disconnect
and
contact
the
installing
electrical
contractor
to
have
the
voltage
condition
corrected.
16.
Confirm
field
wiring
voltage
drop
is
less
than
10%
when
equipment
is
operating.
17.
For
the
unit
to
operate
properly
a
system
air
balance
must
be
performed
to
ensure
correct
air
flow.
Failure
to
do
so
can
damage
the
equipment
and/or
building
and
can
be
a
cause
of
poor
indoor
air
quality.
18.
Coil
air
bypass
adjustment.
For
most
pool
applications
there
will
be
an
air
bypass
section
around
the
evaporator
coil.
This
section
allows
a
portion
of
air
to
bypass
the
evaporator
coil
allowing
the
evaporator
to
have
the
most
efficient
moisture
removal.
The
bypass
is
factory
set
to
a
default
value
and
must
be
field
adjusted
to
ensure
proper
operation
.
With
the
system
running
at
full
load
conditions,
install
refrigeration
gauges.
Adjust
the
bypass
damper
to
maintain
a
suction
pressure
that
corresponds
to
a
saturated
suction
temperature
as
specified
in
the
unit
function
(and/or
the
submittal),
typically
a
saturated
suction
temperature
of
40°F
to
45°F
(5°C
to
7°C).
Too
much
bypass
air
and
the
coils
may
freeze.
Not
enough
bypass
air,
and
the
coil
may
not
remove
enough
moisture
to
satisfy
the
zone
conditions.
19.
Damper
sections:
a)
Flat
mixing
dampers:
Both
the
fresh
air
and
return
air
dampers
are
fully
open
when
the
dampers
are
at
a
45°
angle
when
fully
stroked.
This
provides
optimum
mixing
of
the
air
streams
for
this
damper
arrangement.
b)
Angle
mixing
damper:
Angle
mixing
section
dampers
open
to
an
angle
of
90°
when
fully
stroked.
This
provides
optimum
mixing
of
the
air
streams
for
this
damper
arrangement.
20.
Allow
system
to
operate
until
stable
running
conditions
have
been
established.
21.
Check
and
record
amperage
draw
of
each
motor
and
compressor.
Refer
to
unit
label
for
running
full
load
amps
of
motors
and
compressors.