TM 5-6115-584-12 NAVFAC P-8-622-12 TO-35C2-3-456-1 TM-05682C-12 MAINTENANCE  OF  CONTROL  SYSTEM 4-34.  DESCRIPTION Section XII. AND  FUNCTION. NOTE All  symbols  (CB2,  S1,  etc.)  are  the  same  as used  on  the  wiring  diagram,  figure  1-7,  and elsewhere  throughout  the  manual. 4-35. DC CONTROL SYSTEM. Operation   of   the   dc   control   system   is   as   follows. Operator  controlled  dc  functions  are  all  contained  in three  items  mounted  on  the  control  panel.  These  are the  dc  circuit  breaker  (CB2),  the  master  switch  (S1), and the panel light switch (S2) (see figure 4-33). a.  The  dc  circuit   breaker   (CB2)   controls   all   dc power   to   the   unit.   When   it   is   de-energized   (pulled out),  all  dc  control  circuits  are  de-energized,  except the   battery   charging   system   which   is   self   protected by   fuse   (F1).   This   breaker   can   be   used   for   emer- gency stopping of the unit. b.  The  master  switch  (S1)  controls  all  starting  and operating  of  the  set  under  normal  conditions.  It  is  a five  position  rotary  switch  with  the  extreme  position in  either  direction  being  a  momentary  position.  The five  positions  control  set  operates  as  follows.  When the   master   switch   is   placed   in   position   1,   marked PREHEAT  on  control  panel,  a  circuit  is  completed between  terminals  11  and  15  of  the  master  switch, this   applies   power   to   the   coil   of   the   preheat   relay (K2).  When  the  preheat  relay  contacts  close,  power  is then  applied  to  the  glow  plugs  and  preheater  on  the engine.  This  position  of  the  switch  should  be  used  for starting  any  time  the  engine  is  cold,  or  has  not  been run  for  sometime.  The  normal  period  for  preheating is 1 minute, but can be as long as 1 minute 30 seconds as  conditions  dictate.  This  switch  position  is  momen- tary   so   that   the   preheat   circuit   remains   activated only  as  long  as  the  operator  holds  the  switch  in PREHEAT or START position. When the master switch is placed in position 2,  marked  OFF  on  control  panel, all   dc   circuits   are   de-energized   except   the   panel lights,   battery   indicator,   and   the   battery   charging system.  This  position  is  used  to  stop  the  set  under normal  operation.  When  the  master  switch  is  placed in position 3, marked PRIME & RUN AUX. FUEL on control  panel,  circuits  are  completed  between  ter- minals   11-13,   11-14,   11-17   of   the   master   switch. This  applies  power  to  the  engine  fuel  pumps,  and  the auxiliary  fuel  system  and  also  to  one  side  of  an open contact of relay (K1). This position is used when the   set   is   running   and   the   auxiliary   fuel   system   is being  used,  and  also  to  prime  the  entire  fuel  system before   starting.   Position   4   of   the   master   switch, marked  PRIME  &  RUN  on  the  control  panel,  is  the same   as   position   3   except   that   the   circuit   between terminals  11-17,  of  the  master  switch  is  not  made. This  position  is  used  when  the  set  is  running  and  the auxiliary  fuel  system  is  not  being  used,  and  also  to prime   the   engine   fuel   system   only   before   starting. When   the   master   switch   is   placed   in   position   5, marked START on the control panel, circuits are com- pleted  between  terminals  11-13,  11-14,  11-15,  25-27, 25-28.   The   circuits   between   11-13,   11-14,   11-15 activate the engine fuel pumps, apply power to one side of  an  open  contact  of  relay  K1  and  activate  the  pre- heat  circuit  as  described  in  previous  positions  of  the switch.   The   circuit   between   25-28   of   the   master switch  bypasses  the  safety  devices  which  are  capable of stopping the engine. Bypassing the low oil pressure safety   device   (S5)   is   essential   until   the   engine   has sufficient   oil   pressure   to   close   its   contacts.   By- passing  the  safety  device  completes  a  circuit  to  the engine  fuel  solenoid  and  relay  coil  (K1).  Energizing the  start  relay  (K1)  completes  a  circuit  through  the contacts  of  (K1)  to  the   running  time  meter,  and  to one  side  of  the  low  oil  pressure  switch.  The  circuit between  25-27  of  the  master  switch  applies  battery voltage to the field flash resistor through diode (CR2). This   action   applies   field   flashing   current   to   the exciter  field.  It  sled  applies  power  through  diode (CR1),  which  prevents  starting  set  when  the  battery polarity   is   reversed,   and   the   closed   contacts   of   the start   disconnect   switch   (S7)   to   the   crank   relay   coil (K3).  When  the  crank,  relay  contacts  close,  a  circuit is   completed   to   the   starter   solenoid   (K6),   which closes   and   starts   the   cranking   motor.   With   the engine  fuel  solenoid  energized  and  the  starting  motor cranking  the  engine,  the  engine  should  start  and  ac- celerate   toward   the   speed   setting   of   the   governor. When  engine  speed  passes  approximately  1000  RPM the   start   disconnect   switch   contact   opens   de-ener- gizing  the  crank  relay  (K3)  and  in  turn  the  start solenoid  and  starting  motor.  With  the  engine  ac- celerating  and  ac  voltage  building  up,  the  governor will  take  control  of  the  engine  and  the  voltage  regu- lator  will  bring  voltage  to  the  value  set  by  voltage adjust  rheostat.  By  the  time  the  Generator  Set  is under   control   of   the   regulator   and   governor,   the engine   oil   pressure   will   be   sufficient   to   permit   re- turning  master  switch  (S1)  to  the  PRIME  &  RUN  or PRIME  &  RUN  AUX.  FUEL  position  depending  on desired  set  operation.  The  set  will  now  be  operating under  control  of  the  voltage  regulator  and  governor but  without  any  load.  As  stated  above,  the  set  is  now ready  to  accept  a  load.  Placing  the  ac  circuit  breaker in  the  ON  position  connects  the  selected  generator output  to  the  set  load  terminals.  The  breaker  can  be opened manually or by automatic action of the internal relay  trip  device  in  the  case  of  an  overload  or  a short  circuit.  The  panel  light  switch  activates  the panel lights when placed in the ON position. 4-36. AC lNSTRUMENTATION SYSTEM. Operation  of  the  ac  instrumentation  system  which consists   primarily   of   ammeter   voltmeter   and   am- meter-voltmeter   transfer   switch   is   as   follows.   The function   of   the   ammeter-voltmeter   transfer   switch (S8)   and   the   meter   switching   section   of   the   re- connection  switch  (S6)  is  to  provide  the  connections 4-38