Emerson Liebert PPC 15-30 kVA, Technical Data Manual

Standard Features for All Systems

5

S

TANDARD

 F

EATURES

FOR

 A

LL

 S

YSTEMS

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 

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.)

Shielded Isolation Transformer

Temperature Sensors

Input Circuit Breaker