ARMY TM    5-6115-612-34 MARINE   CORPS   TM   6115-34/8 AIR FORCE TO   35C2-3-471-2 NAVY AG-320B0-MME-000 10-1. PURPOSE   AND   FUNCTION   OF   ENGINE AND   GENERATOR   CONTROLS   AND   INSTRU- MENTS.   (cont) b.  Functional  Theory    of  Operation. (cont) (6)  Battery charging monitor. The control panel BATTERY CHARGING meter allows the operator to see that the  generator  set  batteries  are  being charged while the engine is running. Signal lines are routed directly to the control  panel and  connected  to  the BATTERY  CHARGING  ammeter. (7)  Status  monitoring and con- trol. Both engine and generator status are  monitored  by  the  EECM  while  the engine is running and the generator is supplying power. If a malfunction is detected, the EECM either attempts to correct  the  problem  or  automatically removes power from the contactor (if the  contactor  is  energized)  and  shuts down the engine. To make these deci- sions,    the EECM microprocessor monitors the engine monopole speed sensor, EGT thermocouple, and oil pressure. For the  generator, the  EECM  microprocessor monitors  the  overload, undervoltage, overvoltage, and temperature status via signals  sent  to  it  from  the  GECM.  A detected fault    is monitored for three-fourths of a second to see if it corrects itself before the microprocessor  software  program  takes any action. In general, with  the exception  of  a  minor  overspeed  con- dition, any  detected  fault  results  in display  of  the  fault  on  one  of  the control panel MALFUNCTION lamps, removal   of starting power   to   the aircraft  by  a  disabling  of  the  con- tactor  relay,   and an automatic shutdown of the engine. (a) Engine fault detection and shutdown. An engine fault consists of an  overspeed,  overtemperature,  or  low oil pressure condition. Overspeed is monitored via the speed signal line to the EECM, overtemperature is monitored via the EGT line to the EECM, and oil pressure   is   monitored   via   the   oil pressure and signal line to the EECM. The only fault that does not cause an immediate shutdown   is   an overspeed condition  between  100  and  109  percent of full rated engine speed.     If frequency of pulses on the speed signal line indicates such a condition, fuel flow  to  the  engine  is  decreased  as discussed. If speed increases above 109 percent,   or any of the other three possible faults occur, the  micro- processor initiates    an automatic shutdown  routine. First, the  micro- processor  disables  the  contactor  to prevent  current  from  flowing  to  the aircraft  being  started. This is done by disabling the contactor enable line from  the  microprocessor  to  the  con- tactor gate and buffer on the switch card. This switches the gate output to disable the contactor relay driver and disable the output contactor signal. When  this  occurs,  the  generator  set contactor  relay  deenergizes  to  remove power from the aircraft. Deenergizing the contactor relay also removes +24 Vdc from the control panel CONTACTOR CLOSED  lamp, turning  it  off.  At  the same time, the  microprocessor  places one  or  more  signals  on the status/ control output lines  to  the  switch circuit  card. Regardless  of  where  the fault lies, the generator enable signal is always disabled which turns off the lamp driver circuit. The READY TO LOAD line is thereby disabled, turning out the READY TO LOAD lamp and stopping the HOURMETER. Other signals are also output on any one of the status control lines to indicate where the fault is occurring. If the fault is determined 10-6