Variable Module Management System
(VMMS) mode
Critical load is supplied by the inverter. The
inverter derives its power from rectified
utility AC power, identically to double
conversion mode. In the VMMS mode, the
93PM UPS system is able to optimise the
load level per power module: the operating
efficiency is significantly improved when
operating load is below 50 % of UPS
capacity. The UPS system will
automatically place the redundant power
modules to suspended mode. In case of
any anomalies in utility or a sudden load
increase, the suspended power modules
are able to transfer to online mode with
less than 2 ms transition time.
Energy Saver System (ESS) mode
Critical load is supported securely by utility
power through the static bypass switch
with double conversion available on-
demand with typically less than a 2 ms
transition time, should any abnormal
condition be detected in the utility. When
operating in the ESS mode, the load is
protected with inherent surge suppression.
Operating the UPS in the ESS mode
increases system efficiency up to 99 %,
allowing significant savings in energy
losses without compromising system
reliability
Stored energy mode
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 the battery mode
Bypass mode
Critical load is supported directly by utility
power through the UPS static switch.
3.3.1
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.
3.3.1.1
Double conversion mode
Figure 4: Path of current through the UPS in the double conversion mode
shows
the path of electrical power through the UPS system when the UPS is operating
in the double conversion mode.
© Eaton Corporation plc 2020. All rights reserved.
Revision: 006
Document ID: P-164000493
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Eaton 91PS/93PS UPS 8–40 kW
User’s and Installation Guide