Liebert 1000kVA manual Upper Limit Actual Lower Limit, Elapsed Time Minutes

Operation

Values for Calculated Total Time and Calculated Time Remaining will appear on the screen approxi- mately two minutes after the beginning of the discharge event. Calculated Time Remaining also appears on the Present Status Report screen. Both Calculated Total Time and Calculated Time Remaining will be updated every six seconds, reflecting actual load changes and battery condition. When the Calculated Times become available, they will be displayed in place of the Battery Discharg- ing message on this screen.

Figure 47 Battery time screen (45-minute discharge)

500	VDC				SELECT : MASTER MENU
480					Low Battery Warning
					Calculated Time (Hrs:Min)
460					Total 00:45 Remain 0:01
440
420
400
380		Battery Shutdown = 417
					Rated Time (Hrs:Min)
360		Battery Charge = 3%
					Total 00:25 Remain 0:00
340	0	10	20	30	40	50	60

Time (Minutes)

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 48 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.

59