Battery Charging Operation; Figure 3-4 Typical Battery Charging Curve - Toshiba G9000 Series Installation And Operation Manual

When power is restored after a low battery shutdown, the UPS response is dependent upon whether it is operating in
standalone (SMS) or parallel (MMS) operation.
Standalone Operation:
After restoration of power, the UPS will automatically restart normal operation: rectifier will resume conversion, the
charger recharges the batteries, and the inverter restarts without operator intervention. Load is automatically assumed by
the inverter without operator intervention.
Parallel Operation:
After restoration of power, the UPS will remain offline until an operator restarts the unit using the startup procedures
shown in Section 5.4 E) MMS Start-up Procedure.
Whenever the system is in Parallel Operation, the power drawn by the load is equally shared between all UPS regardless
of the presence or absence of the UPS that are in battery operation.

Battery Charging Operation

As shown in Section 3.2.1, when the UPS is in normal operation, DC Power is utilized to charge the UPS
batteries. The charging characteristics of the G9000 UPS are shown in Figure 3-4 and descriptions of the two
charging periods are below.
Period (A): Charging voltage increases steadily from its minimum until it reaches the float voltage of the battery
system. During this period, the charging current will be at its maximum as long as sufficient power is supplied to
the UPS and there are no load conditions that prevent it. The maximum current is either the Maximum Recharge
Current that the UPS system can provide (see the Battery portion of Section 3.3 "Specifications") or a lower
current limit set via the LCD screen to comply with the battery manufacturer recommendations. This current limit
adjustment should only be performed by a Toshiba Authorized Service Provider.
Period (B): This period begins when the Charging Voltage reaches the float voltage of the batteries. The
charging current will steadily decrease as the batteries approach their maximum state of charge. Once reached,
the UPS will maintain the maximum state of charge on the batteries with minimal Charging Current.
12
(A)
0

Figure 3-4 Typical Battery Charging Curve

G9000 Series UPS 300-750kVA Installation and Operation Manual – 61480-017
(B)
Charging Current Limit
Charging Time
Charging Voltage
Charging Current