Liebert 610 manual Upper Limit Actual Lower Limit, Elapsed Time Minutes

Operation

The Battery Time Remaining graph and the Calculated times are extremely helpful to the operator who has the discretionary authority to order load-shedding activities. The Series 610 automatically samples battery voltage and load current and recomputes every six seconds. This gives the operator fast and accurate feedback on efforts to extend battery time remaining by shutting down non-critical loads.

Figure 37 Accuracy range of values for calculated battery times

Remaining	25
	20
	15
Time
	10
Calculated
	5
	0
	0	2.5	5	7.5	10	12.5	15	17.5	20	22.5	25
					Elapsed Time (Minutes)

Upper Limit Actual Lower Limit

NOTE

While every effort has been made to make the Rated and Calculated Time Remaining values as accurate as practical, these values must be regarded as approximations. At the beginning of the discharge cycle, the Calculated times could be off by as much as ±20% due to such variables as battery initial charge, age of battery and the subsequent load-shedding activities of the operator. Within a few minutes, however, these calculations should settle into their design accuracy of ±10%, with the end-of-discharge tolerance being +0, -10% of actual observed time. In addition, the operator can adjust the settings affecting Rated Total Time after gaining experience with the actual battery and connected load.

The Series 610 dynamically adjusts the Battery Shutdown voltage based on battery characteristics and the length of the current discharge event. If a discharge event extends past 15 minutes (i.e., the load is less than the full design rating), the Battery Shutdown voltage setting is gradually and auto- matically increased, to protect the batteries from deep discharge.

When the battery voltage decreases to a preset limit (see 3.2.6 - Alarm Limit Settings Screen), the Low Battery Warning alarm message appears on the display screen. This warns the operator that the battery voltage is approaching the Battery Shutdown level—about five minutes of time remaining at full rated load.

NOTE

The Low Battery alarm setting is designed to be most useful at full load battery discharge rates. Unlike the Battery Shutdown voltage, the Low Battery alarm setting is not automatically increased and gives proportionately less warning during discharge events lasting longer than 15 minutes. The operator should consult the Battery Time screen or Present Status screen to see the Calculated Time Remaining based on actual usage during the discharge period.

If the battery discharges to the Battery Shutdown level, represented by the lower line on the Battery Time screen, the battery and input circuit breakers trip open and the UPS module is shut down. This protects the battery from being damaged by an extended deep discharge.

! CAUTION

When battery shutdown occurs, no power will be supplied to the critical load unless power is available through the bypass line from the utility source (or from an engine generator set). If you anticipate a battery shutdown (and an engine generator set is not available), either transfer the load to bypass (if available) or perform a controlled shutdown of the critical load.

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