Alpha Technologies APU Control Module (ACM) - Manual (Page 18)

018-340-B0-001 Rev. A 18
4.0 Alarms and Notifi cations, continued
4.1 Alarms, continued
6. Pad Shear (PS) (Latching): Indicates that the main or fuel enclosure has shifted from
its pad mounting position. APU operation is suspended. The alarm is reset when the unit is
returned to its original position and the reset command is issued or when the manual stop
switch is activated.
7. Low Fuel Pressure (LP) (Latching - after 5 activations): Indicates that site fuel supply
(Propane-fueled APU only) is insuffi cient for extended engine operation. The alarm is reset 5
minutes after the fuel supply is replenished.
MINOR ALARMS:
Minor alarms indicate a system fault which, though not indicative of imminent system failure
or shutdown, require service attention as the fault condition could worsen to shut down the
system. A site check by service personnel is recommended.
8. Control Fail (CF) (Latching - after 5 activations): This alarm indicates a control failure
between the ACM and the generator set. Typically this means that the engine did not start or
stop when commanded to do so. This alarm could also be an indication of Major Condition
if engine oil pressure is below safe limits and the APU’s CCG, APS-CP, A2034 or the ECI-2
control unit shuts down or suspends operation of the APU. The alarm is cleared when the
Reset command is issued or when the manual stop switch is activated.
9. Self-Test Fail (TF) (Latching): Status of most recent generator test. The alarm is cleared
when the Reset command is issued, the manual stop switch is activated or another Self-Test
command is issued.
10. Low Ignition Battery (IB): Indicates that the generator’s ignition battery voltage has
fallen below 11.5Vdc. Alarm is cleared when battery voltage rises above 12.0Vdc indicating
battery recovery has begun. Note that low ignition battery voltage is not alarmed during
engine cranking.
11. Auto Mode Disabled (AD): Indicates the position of the ACM control select switch.
When the Run-Auto-Stop (RAS) switch is in a manual (STOP or RUN) position, the ECM has
no control over engine operation and therefore raises an alarm. This is a hardware ‘lockout’
input and cannot be changed via status monitoring.
12. APU Tamper (TP): One of the doors on the APU enclosure is open. The alarm clears
when the door is closed. For confi guration with a separate APU enclosure, (such as the 7.5kw
DC APU) install the provided modifi ed Alarm harness to monitor the APU tamper separate
from the power supply enclosure tamper.
13. DC Bus Fault (DC): Indicates that the power system DC bus voltage, as measured
at the ACM, is less than 1.95 volts per cell. This alarm clears automatically when the bus
voltage exceeds 2 volts above nominal (i.e., 50Vdc in a 48V system).
APU will not start if Pad Shear magnet is not correctly installed below the Pad Shear sensor.
NOTE:
This input requires the ignition battery sense jumper to be removed and a harness installed directly from the
ignition battery terminal through a current limiting resistor, on the positive lead, to a 4 pin mini mate-n-lock
connector. If this option is not utilized do not remove the installed jumper in the ignition batt sense connector.
NOTE: