Eaton 93PR - UPS Operating Modes; Normal Operating Modes

Eaton 93PR 500 kW UPS
User's and Installation Guide 11
If utility power is interrupted or falls outside the parameters specified in Chapter 8 Technical data, the UPS uses a
backup battery supply to maintain power to the critical load for a specified period of time or until the utility power
returns. For extended power outages, the UPS allows you to either transfer to an alternative power system (such as
a generator) or shut down your critical load in an orderly manner. The UPS bypass consists of a continuous-duty static
switch and backfeed protection isolation device K5. The backfeed protection is located in series with the static switch.
Transfers to static bypass are seamless and performed automatically by the system as needed, for example, in case of
an extended system overload.
2.2. UPS Operating Modes
UPS operating modes:
• Normal operating modes:
• In Double Conversion Mode, the critical load is supplied by the inverter, which derives its power from rectified
utility AC power. In this mode, the battery charger also provides charging current for the battery, if needed.
• In Energy Saver System (ESS) mode, the critical load is supported securely by utility power through static
bypass switch with double conversion available on-demand with typically less than a 2 milliseconds transition
time, should any abnormal condition be detected in the utility. When operating in ESS mode, the load is
protected with inherent surge suppression. Operating the UPS in ESS mode increases system efficiency to
99 % allowing
• In stored energy mode, the energy is drawn from a DC backup power source and converted to AC power by the
UPS inverter. Most commonly VRLA batteries are introduced to the system for this purpose, and the mode of
operation is called Battery Mode.
• In Bypass Mode, the critical load is supported directly by utility power through the UPS static switch.
2.2.1. Normal Operating Modes
During normal UPS operation, power for the system is derived from a utility input source. “Unit Online” is
displayed on the front panel, indicating that the incoming power is within voltage and frequency acceptance
windows.
Double Conversion Mode
Figure
2-4 : Path of current through the UPS in Double Conversion Mode shows the path of electrical power
through the UPS system when the UPS is operating in Double Conversion Mode.