TO 31S9-4-38-1 Chg 3
power alone for more than 24 hours-( 12 hours if battery
3-7. Operation Under Emergency Power
is two years old or if operating temperature is -20'F.). If
ac power is off for more than this specified maximum
The Control Unit automatically switches to its
the battery must be recharged as directed in chapter 7.
emergency battery power supply when primary ac power
Failure to do so may create a safety hazard.
fails. It should not be allowed to operate on battery