13. How to Determine On-battery Run Time

Knowing the on-battery run time of the UPS is an important part of UPS use, especially in situations where the protected device uses an operating system that requires some time to gracefully shut down.

1 . To calculate the on-battery run time first determine the total load protected by the UPS in Volt- Amps. Obtain load figures from either the labelling on the protected equipment or the accompanying literature. For loads specified in watts, multiply the specified figure by 1.4. For loads specified in Amps, multiply the specified figure by 120. Note: For equipment that does not specify power consumption, use the estimated equipment load table below.

2 . Add the individual loads to determine the total load.

3 . Compare the total load of your system to the run time table below.

Estimated Equipment Loads

 

Device

 

 

Load (VA)

 

 

Device

 

 

Load (VA)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

External Modem

 

30

 

 

CD-ROM changer

 

 

 

250

 

 

 

 

 

 

 

 

 

 

 

 

 

 

External CD-ROM

 

60

 

 

Tower 486 server

 

 

 

300

 

 

 

 

 

 

 

 

 

 

 

 

 

10Base-T stacking hub

 

80

 

 

Tower Pentium server

 

 

350

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Desktop 486 server

 

200

 

 

RAID array

 

 

 

400

 

 

 

 

 

 

 

 

 

 

 

 

 

Desktop Pentium server

 

250

 

 

Multiprocessor server

 

 

500

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical On-Battery Run Time Versus Load, in Minutes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Load

420 VA

650 VA

 

1000 VA

 

1400 VA

Load

 

650 VA

1000 VA

1400 VA

 

 

 

 

 

 

 

 

 

 

 

 

50 VA

41

90

 

167

 

306

500 VA

 

7.2

14

29

 

 

 

 

 

 

 

 

 

 

 

 

75 VA

27

64

 

125

 

236

550 VA

 

6.5

13

26

 

 

 

 

 

 

 

 

 

 

 

 

100 VA

21

49

 

98

 

190

600 VA

 

5.8

11

23

 

 

 

 

 

 

 

 

 

 

 

 

150 VA

14

29

 

64

 

133

700 VA

 

-

9

19

 

 

 

 

 

 

 

 

 

 

 

 

200 VA

10

22

 

47

 

99

800 VA

 

-

7.7

16

 

 

 

 

 

 

 

 

 

 

 

 

250 VA

7.5

17

 

35

 

74

900 VA

 

-

6.6

13

 

 

 

 

 

 

 

 

 

 

 

 

300 VA

6.2

14

 

27

 

60

1000 VA

 

-

5.8

11

 

 

 

 

 

 

 

 

 

 

 

 

350 VA

5.1

11

 

22

 

50

1200 VA

 

-

-

8.8

 

 

 

 

 

 

 

 

 

 

 

 

400 VA

4.3

9.3

 

19

 

42

1400 VA

 

-

-

7.2

 

 

 

 

 

 

 

 

 

 

 

 

 

450 VA

-

8.2

 

17

 

35

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

18