TM 5-6115-593-34 NAVFAC P-8-631-34 TO-35C2-3-463-2 As    each    generator    satisfies    its    own    quality    circuit, control  relay  (CR)  will  energize  and  provide  120  VAC through  J3-N  to  TB2-5,  6,  7,  or  8  to  its  applicable  MR relay  (MR1,  2,  3,  or  4)  in  the  ACM.    However,  the  first MR to be energized will lock out all other MR relays and also  provide  a  closure  to  its  generator  circuit  breaker control  circuit  via  its  applicable  normally  open  contact (TB3-1 through TB3-8) through J3-D and J3-E.  The first set to close its circuit breaker via MR will also energize its own breaker control relay (BCR)which now disconnects its synchronizer to electric governor (2301) connection    which    is    no    longer    needed    since    this generator is already on line.  Once all other units have satisfied   their   quality   circuit   and   energized   CR,   their respective    synchronizers    will    be    energized    via    CR contacts  at  terminal  one  of  the  synchronizer.    The  fact that     all     other     MR     relays     have     locked     out     and synchronizers are now energized, enables the remaining units   circuit   breakers   to   be   closed   only   when   proper synchronization has taken place.  It should be noted that K106   sync   check   relay   (N.   O.   contacts   5   and   6)   is always in the circuit breaker closure circuit in series with MR   closure   contacts   and/or   the   synchronizer   closure contacts.      This   will   preclude   any   set   circuit   breaker closure, in automatic or manual unsynchronized. As  each  set  circuit  breaker  (CB2)  closes,  its  auxiliary contacts (CB2-5) will close allowing 120 V.A.C. via J3-P to TB2-9, 10, 11 or 12 to energize each sets respective BR1-BR4  relay.    These  BR  relays  along  with  the  24 VDC available to LR1 (LRTD1) - LR 4 (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 (adjustable) 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 re-close    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   pre-determined 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  1-300 second (adjustable) time out before de-energizing.  This 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. 17-29