Stored Energy And Battery Mode; Figure 2-6. Path Of Current Through The Ups In Battery Mode - Eaton 93PR Series User And Installation Manual

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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 UPM

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: Path of current through the UPS in Battery Mode shows the path of

electrical power through the UPS system when operating in Battery Mode.

Internal relay contacts

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 the bypass source is available, the UPS transfers to bypass instead of shutting down.

If at any time during the battery discharge the input power becomes available again, K1 and K5 close and the

UPS returns to normal operation. The UPS will also start to recharge batteries to restore the capacity.

Battery breaker

25-75 kW

User's and Installation Guide

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