Alpha Technologies FlexNet ELPM 300-48D - Manual (Page 14)

14 010-322-C0-003, Rev C
In order to correctly receive the alarm signals, it is recommended to put a pull-up resistor
between the receive circuit’s logic power (3.3V or 5V) and each alarm line at the alarm
signal monitor side, as shown below. The resistance may vary per current requirement of the
receive circuit.
All four alarm lines are LOW at the normal operation. When an alarm is present, the
corresponding line will be HIGH. For example: when AC is turned off, the monitor will see a
HIGH presence at AC fail line while the remaining three alarm lines—Repl Batt, Batt Low and
Miss Batt—remain LOW.
Time Delay in Reporting Alarm
Customers may see a time delay between failure and alarm reports. An alarm signal is
reported only after a failure persists for a certain period of time. This time delay is designed
to avoid customers being annoyed by trivial short period failures (for example: short time AC
failure).
Time Delay for Each Alarm
AC fail — The unit reports AC fail after the battery voltage is less than 52.8V and the battery
discharges for 17 Amp-mins.
Batt Low — The unit reports Batt Low after the battery voltage is less than 44V for 30
seconds.
Batt Miss — The unit reports Batt Miss after the battery is disconnected for 30 seconds. It
may report Batt Low at the same time.
Repl Batt — the unit reports Repl Batt after it diagnoses the battery as bad. However, the
unit runs a battery diagnosis once a month; it might take awhile for the system to diagnose
battery failure if the failed battery does not also have other problems (such as low battery
voltage).