Standard Features For All Systems; Panelboards - Emerson Liebert PPC 15-30 kVA Technical Data Manual

S F
TANDARD EATURES FOR
Shielded Isolation Transformer
All Liebert distribution and conditioning systems
incorporate standard features that ensure load pro-
tection and simplify maintenance.
Precision Power Centers use quality, dry type,
shielded isolation transformers for noise reduction
up to 120 dB, with harmonic voltage distortion of
0.5 percent. Depending on kVA capacity, output
impedance is between 3 and 5.5 percent, while full-
load efficiency is between 96.5 and 98 percent.
The transformer has temperature sensors in the
windings to provide an alarm if internal temperature
exceeds 180°C. It will shut down the system if inter-
nal temperature exceeds 200°C. Full Class H 220°C
transformer insulation and all copper windings are
used for long life and efficient operation.
A main input circuit breaker provides either manual
control, or automatic shutdown of the system in the
event of an overcurrent condition. The breaker is
sized for 125 percent of the system input full load
amperes. In addition to manual and thermal-mag-
netic trip, the input breaker can be tripped by an
electrically actuated shunt trip mechanism. As a
standard feature, the shunt trip of the input circuit
breaker is activated by the 200°C temperature sen-
sor, local Emergency Power Off switch, and Manual
Restart circuit.
The local Emergency Power Off (EPO) switch is an
illuminated push button, easily accessible for emer-
gency shutdown, but fully guarded by a hinged cover
to prevent accidental operation.
The manual restart circuit shunt-trips the main
input breaker whenever input power fails. This iso-
lates the system from repetitive power applications
during fault-clearing operations by the utility, and
allows an orderly restart of the system when normal
power returns.
The manual restart circuit can be disabled by the
manual restart select switch. The auto position of the
switch defeats manual restart, and allows the condi-
tioner to automatically restart when power returns.
Auto restart is useful for unattended remote sites
where the load can automatically restart, and in
A S
LL YSTEMS
Temperature Sensors
those applications where the manual restart function
is provided elsewhere in the system.
The low-voltage shunt trip circuit also allows system
shutdown by external relays, Remote Emergency
Power Off (REPO) switches, or other remote devices.
A double-pole, double-throw (dpdt) building interface
relay is powered by a 24 VDC supply from the output
of the unit. Energized whenever the system is on, the
relay drops out if the output voltage disappears. The
relay can be used for remote alarming of system
shutdown, or shutdown interface with additional
loads such as environmental control units.
Power conditioner system components are housed in
a welded steel frame with removable panels for max-
imum accessibility to the interior. For safety and
security, any panels that provide access to high volt-
age require a tool for removal.

Panelboards

One 42-pole panelboard is provided on 15 and
30 kVA Precision Power Centers. Two 42-pole panel-
boards (for a total of 84 poles) are provided on 50
through 125 kVA Precision Power Centers. Three
42-pole panelboards (for a total of 126 poles) are pro-
vided on 150 through 225 kVA Precision Power Cen-
ters. (The three-panelboard configuration is not
available on Top Exit units.) Each panelboard is
enclosed for safety and has individual isolated neu-
tral and safety ground busbars.
Each panelboard is protected by a main circuit
breaker, which also allows manual shutdown of the
entire panelboard without affecting the other panel-
board(s).
Output circuits are protected by single-, two-, or
three-pole thermal-magnetic molded-case branch cir-
cuit breakers sized specifically for the load to be
served. (Standard panelboards use plug-in breakers.)
5

Standard Features for All Systems

Input Circuit Breaker