
1.4 Major Internal Components and Operating Principle
The UPS is composed the components described in Figure 1.3 on the facing page. Table 1.2 below,
describes the operation of various circuits through the components.
Component Operation/Function
Transient Voltage
Surge
Suppression
(TVSS) and
EMI/RFI Filters
Provide surge protection. Filter electromagnetic interference (EMI) and radio frequency interference (RFI).
Minimize any surges or interference present in the utility line and protect the sensitive equipment even when on
internal bypass power.
Rectifier/Power
Factor
Correction (PFC)
Circuit
In normaloperation, converts utility AC power to regulated DC power for use by the inverter while ensuring that
the wave shape of the input current used by the UPS is near ideal. Extracting this sine-wave input current
ensures efficient use of utility power and reduces distortion reflected on the utility making cleaner power
available to devices that are not protected by the UPS.
Inverter
In normaloperation, inverts the DC output of the power-factor-correction circuit into precise, regulated sine-
wave AC power. When utility power fails, the inverter receives energy from the batteries through the rectifier. In
both Normal mode and Bypass mode, the UPS inverter remains on-line, generating clean, precise, regulated AC-
output power.
DC-DC Charger When the UPS is connected to utility power and the rectifier is operating, the battery charger regulates energy
output from the rectifier/PFC to continuously recharge the batteries.
Static Bypass
Switch
In the event of an output overload, over-temperature condition, or other failure, the switch automatically
transfers connected equipment to bypass power.
Batteries
Up to 4 strings of long-life, valve-regulated, non-spillable, lead-acid batteries depending on back-up run-time
requirements. See Table 7.3 on page55, for approximate run times.
NOTE: To maintain battery design life, operate the UPS in an ambient temperature of 68°F to 77°F (20°C
to 25°C).
Maintenance
Bypass Breaker electrically isolates the UPS and internal batteries for maintenance.
Table 1.2 Major Component Operation
Vertiv | Liebert® EXS™ Installer/User Guide
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