Battery Mode; Figure 2-7: Route Of The Electric Energy Running Through The Ups In Battery Mode - Eaton 93PR Series Installation And Operation Manual

2.2.2.

Battery Mode

In Online mode or ESS mode, the UPS will supply power to the load through the battery or other
energy storage if AC power fails or AC power is not in compliance with the specified parameters.
On the display, the state of the UPS is shown as "Battery Mode", and the UPS is in "In Service"
state. In battery mode, the battery supplies emergency DC power, which will be converted to
Figure 2-7
controllable output by the inverter. indicates the route of the electric energy running
through the UPS in battery mode.
Internal relay contacts
Battery breaker

Figure 2-7: Route of the electric energy running through the UPS in battery mode

When AC power fails, the rectifier cannot convert AC power into DC output to supply the
inverter. The input relay K1 will be switched off, and the battery will supply UPS output via the
inverter. As the inverter runs uninterruptedly during the conversion process, the UPS can supply
uninterruptible power to the load continuously. If the static bypass and the rectifier of the UPS are
energized by AC power, the battery will discharge to a very low voltage when the AC power and
static bypass cannot restore or AC power is not within the specified range necessary for normal
system operation. At this moment, the inverter cannot continue to supply power to the load. In this
event, the UPS will give an audible and visual alarm, indicating that the battery capacity is very
low and the system will shut down soon. Unless AC power recovers, the UPS can support output
for 2 minutes at most before the system shutdown. If a bypass battery is available, the UPS will
switch to bypass mode rather than shut down.
Whenever AC power recovers again during the battery discharge, K1 will be closed, and the UPS
will return to online operation mode. The UPS will start charging the battery to recover its capacity.
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