Eaton Electrical 9390 - Manual (Page 5)

5 www.eaton.com/powerquality 1.800.356.5794
Consistent efficiency
throughout UPS
load range
Many UPSs cite greater than
90% efficiency without mention
of low or no load range. Today’s
average system operates at only
55% of its rated load or capac-
ity range. However, efficiency
is usually reduced in this lower-
load operating status—not so
with the 9390, which reaches
optimal efficiency rates at less
than half load—and maintains
this optimal efficiency through-
out the load range!
Low input current
THD enhances
generator compatibility
Electronic devices and UPSs are
built with some components
that are non-linear. When voltage
is applied to a circuit constructed
of non-linear components, the
circuit may not respond linearly
(current may not follow the volt-
age in a linear manner). These
components may even create
frequencies other than the fun-
damental applied frequency (60
Hz).
These frequencies (harmonics)
occur in odd multiplies of
60 Hz. The degree of occurrence
is called total harmonic distor-
tion (THD). If the power source
can’t respond to all frequencies
demanded by the circuit, then
further distortion of the applied
voltage may occur—creating
more complication. Every UPS
produces a level of harmon-
ics. Unchecked, harmonics can
reduce overall power factor,
cause sensitive devices to mal-
function, prematurely age equip-
ment, and cause screens and
displays to flicker.
To avoid these negative effects,
the 9390 uses a special input
circuit that keeps current THD
at less than 4.5% at full load—
without compromising efficien-
cy. As a result, the 9390 trans-
fers maximum power between
the source and protected load
and is exceptionally compatible
with multiple power sources,
especially auxiliary generators.
In the Power Performance chart
on the previous page, note that
most manufacturers require an
input filter to minimize THD.
This added filter results in lower
efficiency for the UPS—a con-
sequence not generally noted in
marketing materials.
LOAD Power Factor RANGE Chart
Leading Lagging
-1 -0.75 -0.50 -0.25 0 0.25 0.50 0.75 1
kVAr
kW
PF=0.9 100% kW PF=1 PF=0.9
PF=0.8
Without derating
1
0.75
0.50
0.25
Many competitive
UPSs cannot operate
in this range without
significant derating
Full range of load power factor
Power factor perfor-
mance maximizes com-
patibility and meets
high power factor load
requirements
Power factor (PF) describes
the slight phase shift between
voltage applied to a circuit and
current that the circuit draws
in response to the applied volt-
age. The maximum power fac-
tor possible is unity (1.0), or no
phase shift between the voltage
applied and the circuit current
response—maximum transfer
of power between source and
load. However, in the real world,
the UPS must be able to accept
power from and deliver power to
circuits that have a wide range
of power factors.
Older or worn equipment often
results in lower power factor
readings. Some new servers
operate at unity power factor.
Lightly loaded facilities such as
brand new data centers, can
often show leading power factor
readings.
On output, the ultra high-speed
switching pulse width modula-
tion (PWM) inverter enables the
9390 to provide its full rated
power capability to the load,
down to 0.9 leading power fac-
tor without de-rating.
Double-conversion
design offers highest
available protection
Unlike other commercially avail-
able UPS technologies, the
double-conversion design com-
pletely isolates output power
from all input power anomalies
and delivers 100% conditioned,
perfect sine wave output—
regulating both voltage and
frequency, providing protection
from all nine common power
problems.
Due to the 9390’s built in high-
efficiency capability, it operates
in a consistent, efficient status
without compromising power
protection. Even when present-
ed with the most severe power
problems, power output remains
stable with the 9390. Output
voltage THD is held within two
percent of nominal specification
for linear loads, within five per-
cent for non-linear loads—mak-
ing the 9390 ideal for supporting
equipment that is sensitive to
a distorted voltage input as a
result of harmonic loads. In the
event of a utility power failure,
there is no delay transferring to
backup power.