Alpha Technologies APU Control Module (ACM) - Manual (Page 25)

25 018-340-B0-001 Rev. A
5.0 System Self-Test and Maintenance, continued
5.1 Self-Test, continued
If AC line should fail during a test, the test will terminate normally but the engine will continue
to run until line returns. If the test fails because the DC Bus alarm activates, the test will
terminate, the self-test fail alarm will activate but the generator will continue to run until the
DC Bus alarm clears. The Self-Test Fail alarm may be cleared via a reset command or by
successfully running a subsequent test. The programmable, internal ACM variables listed
below control automatic self-tests.
Auto-Test Interval
This feature represents the number of days between automatic tests. Auto-test interval is 17
days.
Auto-Test Countdown
This countdown timer is monitored by the ACM to determine when the next automatic test
should be initiated. Although this timer is normally used as a status indicator, it can be used to
set the start time for the next auto-test. For example, if the user wants to start the automatic
test sequence at 12:30pm and it is presently 10:15am, they can wait until 10:30 and program
Auto-Test Countdown to 2 hours. Subsequent tests will begin at nearly the same time of day
so long as the ACM doesn’t lose power in the interim. The ACM sets Auto-Test Countdown
whenever the Auto-Test Interval is changed. Thus, if the Auto-Test Interval is programmed to
10 days, the ACM will set Auto-Test Countdown to 240 hours.
Auto-Test Duration
The length of each Auto-test is measured in minutes. The default test duration is 10 minutes.
The test duration may be set between 10 and 120 minutes.
Manually enabling the Autotest feature
Switch SW5-8 is used to enable the autotest feature with a 14-day test interval. The fi rst
autotest will begin 14 days from the time the ACM is powered up with the confi guration switch
changed from 0 to 1 (OFF to ON). To disable the autotest sequence, place switch SW5-8 in
the OFF position and restart the ACM. It is important to understand that upon power up, the
ACM looks for a change in the switch position before it changes the test control parameters.