Alpha Technologies APU Control Module (ACM) - Manual (Page 17)

17 018-340-B0-001 Rev. A
4.0 Alarms and Notifi cations
4.1 Alarms
The ACM is capable of reporting “Major” alarms, “Minor” alarms and “Notifi cations”. The
following are detailed descriptions of each.
MAJOR ALARMS:
A Major alarm indicates failure of a critical component or some other situation (pad shear,
for example) where the system either has gone off-line, or system failure and/or shutdown
is imminent. Major alarms cause the engine to shutdown immediately and generally prevent
further operation. Most major alarms are latched by the ACM. A site check by service
personnel is required to repair the fault and clear the system. Placing the RAS switch in the
STOP position for three (3) seconds, then switching back to AUTO will clear any latched
alarms and start the generator if the cause of the alarm has been corrected.
1. Engine Over-Temp (OT): Indicates engine temperature has exceeded safe limits and
operation of the unit has been suspended. The alarm is reset when the engine temperature
falls below safe limits.
2. DCIU Breaker trip (DT) (Latching): For 7.5kw DC generators with a DCIU only. The
DICU breaker has tripped because the APU alternator output voltage is too high. Operation
of the unit has been suspended. The alarm is cleared when the Reset command is issued or
when the manual stop switch is activated.
3. Engine Over-Crank (OC) (Latching): Indicates the failure of the engine to start when
commanded to do so. Clear the alarm after the DCIU breaker trip issue is resolved. To clear
the alarm initiate the Reset command or move the RAS switch to stop the return to AUTO or
RUN.
4. Gas Hazard (GH) (Latching): The concentration of hydrocarbon fuel in the power
system’s enclosure air space has exceeded safe limits or 10%-20% of the Lower Explosive
Limit (LEL) For more than three (3) or ten (10) seconds depending on the detector use. APU
operation is suspended. The alarm is cleared when the Reset command is issued or when
the manual stop switch is activated.
5. Water Intrusion (WI) (Latching if encountered while the engine is running): Water
level within the main or fuel enclosure has exceeded safe limits for generator operation. APU
operation is suspended while this alarm is active. The alarm is reset when the water level falls
below maximum limits if alarm occurs while the APU is not running.
Fig. 4-1, Alarms Matrix
Major 1 2 3 4 5 6 7 8 9 10 11 15
Abbreviation OT DT OC GH WI PS LP CF TF IB AD SR
Major
Minor
Notify
Comm
System
14
LF
13
DC
12
TP
1. Engine Over-Temp (OT) 9. Self-Test Fail (TF)
2. DCIU Breaker Trip (DT) 10. Low Ignition Battery
(IB)
3. Engine Over-Crank
(OC) 11. Auto-mode Disabled
(AD)
4. Gas Hazard (GH)* 12. Tamper (TP)
5. Water Intrusion (WI) 13. DC Bus fault
6. Pad Shear (PS)* 14. Line Failure (LF)
7. Low Fuel Pressure (LP) 15. Service Required (SR)
8. Control Fail (CF)
Control Fail (8), can be associated with a low oil pressure condition. Verify engine oil level prior to running or testing APU.