Stored Energy And Battery Mode; Figure 2-6: Path Of Current Through The Ups In Battery Mode - Santak CASTLE Series User Manual

2.2.2.

Stored Energy and Battery Mode

When running normally in double conversion or ESS mode, the UPS automatically transfers
to supply the load from batteries or other stored energy source if a utility power outage
occurs, or if the utility power does not conform to specified parameters. The UPS status
indicated on the display is "On Battery", and the UPS status is "Active". In Battery Mode,
the battery provides emergency DC power which is converted to regulated output power by
the inverter. Figure 2-6 shows the path of electrical power through the UPS system when
operating in Battery Mode.
Internal relay contacts
Battery breaker

Figure 2-6: Path of current through the UPS in Battery Mode

During a utility power failure, the rectifier no longer has an AC utility source from which to
supply the DC output current required to support the inverter. The input relay K1 opens and
the UPS output is powered from batteries through the inverter. As the inverter operates
uninterrupted through the transition, the load remains supported continuously without
disturbance. If the UPS static bypass is supplied from the same source as the UPS rectifier,
the backfeed protection contactor K5 also opens. The opening of K1 and K5 prevent system
voltages from bleeding backwards and re-entering the input source through the static switch
or rectifier.
If the input power fails to return or is not within the acceptance windows required for normal
operation, the battery continues discharging until a DC voltage level is reached where the
inverter output can no longer support the connected loads. When this event occurs, the UPS
issues a set of audible and visual alarms indicating that the batteries are having a minimal
capacity left and a system shutdown is imminent. Unless utility power is restored, the output
can be supported for maximum two minutes before the output of the system shuts down. If
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