TM 5-6115-593-12 TO 35C2-3-463-1 available  to  LR1  (LRTD1)  -  LR4  (LRTD4)  make  up  the prioritized  feeder  breaker  control  circuits.    The  first  set to  close  to  the  bus  will  energize  a  BR  relay  which  will always   close   LR1   (Load   Relay)   and   its   2-20   second (adjust-  able)  time  delay  (LRTD1)  secondly.    Each  LR and  LRTD  should  control  loads  not  to  exceed  250KW each.        LRTD's    allow    a    time    delay    between    load applications as to allow engine turbochargers to build up speed.      LR1   relay   will   always   be   the   first   relay   to energize  on  start-up  and  the  last  relay  to  de-energize when the sets are shut down.  Therefore, it is classified as  the  #1  priority  feeder  breaker  control.    When  LR1 relay energizes, it also prevents RR relay from being re- energized   if   utility   power   returns   via   LR1   normally closed contacts in series with RR relay coil.  This allows all  sets,  which  are  in  the  automatic  mode,  to  complete their   start-up   and   parallel   cycles   regardless   of   utility power returning.  As each remaining set is automatically synchronized  and  paralleled  to  the  bus,  the  remaining LR  and  LRTD  relays  will  energize  in  numerical  order. The    ACM    has    a    3    position    rotary    switch    labeled "Instant",   "Time   Delay"   (TD)   and   "No   Return".      This switch   allows   the   user   three   options   as   to   what   will happen when the utility power returns after a failure.  If the switch is in the "Instant" return position, immediately, when the utility power returns, the utility 120 VAC will be supplied   through   energized   T.D.   relay   normally   open contacts through S1 to TB2-1, 2, 3, and 4 to J3-C on all units, energizing the breaker trip relay (BTR) which will shunt trip each unit's circuit breaker (CB2).  At this time, all  BR,  LR  and  LRTD  relays  de-energize  causing  the LR1  normally  closed  contact,  in  series  with  RR  coil,  to reclose    allowing    RR    relay    to    re-energize,    thereby allowing the utility breaker to close back to the load.  In the "TD" position, a 3-30 minute (adjustable) time delay via UTR (Utility Trip Relay) allows a predetermined time delay after the utility power returns before the unit circuit breakers  (CB2)  are  tripped.    This  insures  utility  power has returned to stay, avoiding unnecessary transfer and re-transfers  of  the  utility  breaker  control.    In  the  "no return"  position,  the  generators  will  carry  the  load  until switched off by the operator. At  the  same  instant  when  all  units  CB2's  are  tripped open  via  BTR,  SDT  (Shut  Down  Timer)  begins  a  300 second (adjustable) time out before de-energizing.  The SDT relay allows the engines to continue to run and cool down after the load has been removed. At the end of this time delay period, SDT N.O. contacts re-open, removing the 24 VDC to TB4-5, 6, 7, 8 and J3- B which in turn allows K5 relays to de-energize and stop all units. This  completes  the  automatic  start  and  shutdown  cycle of the generator set via the ACM. 5-14. INSTALLATION.  The automatic control module is  a  self-housed  unit,  for  indoor  or  outdoor  operation. The unit should be placed as level as possible, on firm, dry,  footing.    Allow  approximately  24  inches  (62  cm) clearance  on  each  side  of  the  unit  for  access  during operation  and  maintenance.    See  paragraph  2-11  for information on connecting the automatic control module, FO-12   for   a   schematic,   and   FO-15   for   a   connection diagram. 5-15. LUBRICATION.    The  automatic  control  module requires no lubrication. 5-16. PREVENTIVE  MAINTENANCE  CHECKS  AND SERVICES  (A,  N,  MC).    To  ensure  that  the  automatic control  module  is  always  ready  for  operation,  inspect systematically  so  that  defects  may  be  discovered  and corrected    before    they    result    in    serious    damage    or failure.      Perform   the   preventive   maintenance   checks and  services  in  accordance  with  table  5-4.    Air  Force users  shall  refer  to  the  applicable  inspection  manuals and  work  card  sets  in  T.O.  35C2-3-  series  for  periodic preventive maintenance requirements and table 5-4 for detailed  procedures.    Marine  Corps  users  shall  refer  to the current issue of TM 11275-15/1.  See par. 2-11 and fig. 2-19 for operation. 5-17. OPERATOR/CREW TROUBLESHOOTING. Table 5-5 contains troubleshooting information for use in correcting  operating  troubles  which  may  develop  in  the generator   set   when   used   with   the   automatic   control module.  Each malfunction is followed by a list of tests or   inspections   which   will   help   to   determine   probable causes and corrective actions to take.  Perform the tests or inspections and corrective actions in the order listed. Any trouble beyond the scope of crew level maintenance    shall    be    referred    to    the    next    higher (organizational) 5-14