TM 1-1510-218-10 2-107 GENERATOR   T2   ,   are   located   on   the   overhead control   panel   under   the    MASTER   SWITCH.      The toggle   switches   control   electrical   power   from   the designated generator to paralleling circuits and the bus distribution system.  Switch positions are  RESET / ON / OFF.   RESET  is forward (spring-loaded back to  ON), ON  is  center,  and   OFF  is  aft.    When  a  generator  is removed from the aircraft electrical system, due either to fault or from placing the GEN / GENERATOR switch in the  OFF position, the affected unit cannot have its output    restored    to    aircraft    use    until    the    GEN    / GENERATOR switch is moved to RESET, then  ON. d.  Master Switch.   All electrical current may be shut off using the  MASTER SWITCH bar that extends above   the    battery    and    generator    switches.        The MASTER   SWITCH   bar   is   moved   forward   when   a battery or generator switch is turned on.  When moved aft, the bar forces each switch to the OFF position. e.   Volt-Loadmeters   C  D  T1.    Two  meters  on the  overhead  control  panel  display  voltage  readings and  show  the  rate  of  current  usage  from  left  and  right generating  systems.    Each  meter  is  equipped  with  a spring-loaded push-button switch which, when manually  pressed,  will  cause  the  meter  to  indicate main  bus  voltage.   Each meter  normally shows output amperage    reading    from    the    respective    generator, unless the push-button switch is pressed to obtain bus voltage  reading.   Current consumption is indicated as a percentage of total output amperage capacity for the generating system monitored. f.    DC Load and Voltmeters   T2  .    Four  digital meters, located on the overhead panel, display voltage readings and show the rate of current usage from the left   and   right   generating   systems.      The   two   load meters indicate output amperage as a percent of rated capacity    from    the    respective    generator.        Current consumption   is   indicated   as   a   percentage   of   total output  amperage  capacity  for  the  generating  system being   monitored.      The   two   voltmeters   indicate   bus voltage for the respective generating system. g.  Battery   Monitor.      Nickel-cadmium   battery overheating  will  cause  the  battery  charge  current  to increase if thermal runaway is imminent.   The  aircraft has   a   charge-current   sensor,   which   will   detect   a charge  current.    The  charge  current  system  senses battery current through a shunt in the negative lead of the   battery.      Any  time  the  battery  charging  current exceeds  approximately  7-amperes  for  6  seconds  or longer,  the  yellow   BATTERY   CHARGE  annunciator light  and  the  master  fault  caution  light  will  illuminate.   Following  a  battery  engine  start,  the  caution  light  will illuminate approximately 6 seconds after the generator switch  is  placed  in  the   ON  position.     The  light  will normally  extinguish  within  2  to  5  minutes,  indicating that the battery is approaching a full charge.   The time interval  will  increase  if  the  battery  has  a  low  state  of charge,  the  battery  temperature  is  very  low,  or  if  the battery  has  previously  been  discharged  at  a  very  low rate   (i.e.,   battery   operation   of   radios   or   lights   for prolonged   periods).        The   caution   light   may   also illuminate  for  short  intervals  after  landing  gear  and/or flap  operation.    If  the  caution  light  should  illuminate during   normal   steady-state   cruise,   it   indicates   that conditions   exist   that   may   cause   a   battery   thermal runaway.    If  this  occurs,  the  battery  switch  shall  be turned  OFF and may be turned back ON only for gear and  flap  extension  and  approach  to  landing.    Battery may   be   usable   after   a   15   to   20   minute   cooldown period. h.  Battery   Temperature   Monitoring   System T2   .      A   battery   temperature   indicator   system   is provided   to   monitor   the   temperature   of   the   nickel cadmium  battery.    The  system  consists  of  a  battery temperature probe, a dc-powered (ANVIS) post lighted indicator,     push-to-test     switch     and     system     circuit breaker.   The  battery  temperature indicator and push- to-test switch, placarded   BAT  TEMP  TEST,  are  both located  on  the  pilot's  subpanel.    The  systems  circuit breaker,   placarded   BATT   TEMP,  is  located  in  the WARNING   section   of   the   overhead   circuit   breaker panel.      Dimming   of   the   post   lighted   instrument   is provided through the SUBPANEL LIGHTS rheostat. The    instrument    indicating    range    is    100    °F (bottom  of  scale),  to  190  °F  (top  of  scale).    A  red, yellow and green band located alongside the indicator scale    and    two    annunciators    (lower)   c aution    and (upper)  warning  located  on  the  face  of  the  indicator provide  visual  battery  temperature  information.   When illuminated, the lower annunciator indicates the battery temperature  exceeds  120  °F,  the  upper  annunciator indicates the battery temperature exceeds 150 °F. The  push-to-test  switch,  placarded   BAT  TEMP TEST,  when pressed and held, will normally move the indicator pointer to the top of the scale and illuminate both  annunciators.    The  pointer  rate  of  rise  will  vary, being somewhat slower with colder battery temperatures.   If a probe is faulty or leaking, or a wire is broken, the pointer may not move at all  or may stop down the scale.  Allow approximately 45 seconds for the  pointer  to  move  to  the  top  of  the  scale  in  normal temperatures; 60 seconds in colder temperatures. i.    Generator    Out    Warning    Lights.         Two caution/advisory  annunciator  panel  lights  inform  the pilot when either generator is not delivering current to the aircraft dc bus system.  These lights are placarded #1 DC GEN and  #2 DC GEN.    Two flashing MASTER CAUTION  lights  and  illumination  of  either  fault  light indicates that either the identified generator has failed