TM 5-6115-593-12 TO 35C2-3-463-1 b. Single Unit Operation.  Once the engine has stabilized  and  is  running  normally,  the  load may  be  applied  to  the  main  generator  G1 output   terminals   through   the   heavy   duty contacts    of    motor    driven    circuit    breaker CB2.        CB2    closes    when    relay    K22    is energized   through   a   series   circuit   which consists   of   various   relay   contacts   of   the generator   fault   protection   circuit   and   AC PWR   CKT   BKR   switch   S3.      With   K22 energized,  the  motor  of  CB2  is  activated, closing    its    contacts    and    applying    main power to the load. (1) Output  Frequency  Regulation.    With the AC output now applied to the load, the  generator  output  frequency  must be  maintained  at  either  the  50  or  60 Hz required by the load. Generator or output    frequency    is    controlled    by adjusting  engine  speed  (frequency  is directly proportional to engine speed). A  magnet  imbedded  in  the  magnetic pickup    PU1,    which    is    mounted    in close proximity to the flywheel, induces a series of voltage pulses for every revolution of the engine.  These voltage   pulses,   whose   number   per minute indicates engine rpm, are sent to  governor  actuator  controller  A106. A106  processes  and  amplifies  these pulses in conjunction with other generator   load   sensing   inputs   (such as  a  generator  current  and  voltage) and generates a control voltage proportionate   to   engine   speed   and generator  output  requirements.    This output is applied to governor actuator solenoid   L101.      In   response,   L101 varies  the  amount  of  control  placed on   the   fuel   injection   pump   by   the electro   hydraulic   governor   actuator. The    fuel    injection    pump    regulates engine speed by adjusting the engine's rate of fuel consumption. (2) Output Voltage Regulation. Generator G1 output voltage is indirectly  controlled  by  the  amount  of current    flowing    in    the    generator's exciter field. The extent of this control is    determined    by    voltage    regulator VR101 which senses generator output voltage.      The   source   of   the   control current is a permanent magnet generator mounted on the same shaft as  the  main  generator  exciter.    After being   made   proportional   to   the   G1 output voltage by VR101, the permanent   magnet   generator   output (in  addition  to  supplying  short  circuit current)  is  used  to  determine  exciter field current. A motor-driven potentiometer    R101    (controlled    by VOLT    ADJ    switch    S6)    is    used    to manually adjust main generator output   voltage.      This   potentiometer which is driven by B5, is connected to VR 101. c. Parallel   Operation.      To   increase   the   total available  power,  the  generator  set  may  be operated  in  parallel  with  as  many  as  three additional     generator     sets.          During     the parallel    mode    of    operation    the    phase, frequency,  and  amplitude  of  the  generator sets must be made to coincide.  Amplitudes can    be    made    to    coincide    by    manually adjusting  and  comparing  the  outputs  of  the various generator sets. The  phase  sequence  of  one  generator  set must first be determined and then compared with  the  phase  sequence  of  the  set  to  be paralleled.  This is accomplished by PHASE SEQUENCE switch S103 and relays K103-1 and  K103-2.    If  the  phase  sequence  of  the generator  windings  are  1-2-3,  relay  K10-13 will     energize,     closing     its     4-5     contacts causing  the  1-2-3  indicator  lamp  DS41  to light.  If the phase sequence is 1-3-2, relay K103-2 will energize and the 1-3-2 indicator lamp DS42 will light. Switch S103 determines  whether  the  generator  windings or the generator buss is to be monitored. After phase sequence has been established, the operator must set switch S8 to PARALLEL OPERATION, thereby energizing relay K23 and 1-27