TM5-6115-585-34 NAVFAC    P-8-623-34 TO-35C2-3-455-2 TM-05684C/05685B-34 period  of  time.  The  applied  voltage  must  not  be  so high  as  to  injure  the  insulation  unless  the  insulation was  initially  defective. (2)   Apparatus.   Use   acceptable   high   potential   test apparatus,  following  the  operating  instructions  of  the manufacturer. (3)   Procedure. (a)   Adequately   ground   high   potential   apparatus to   a   water   pipe   or   similar   electrical   ground   in   ac- cordance  with  instructions  accompanying  the  appara- tus. (b)  Disconnect  or  remove  rectifiers  and  semi- conductors   from   the   circuit   prior   to   conducting   the tests. (c)  Isolate  the  rotor  windings,  the  main  stator windings,   and   the   exciter   stator   windings.   This   is accomplished   by   disconnecting   the   various   windings from  any  associated  control  circuits  or  other  con- nections. (d)  Connect  the  high-voltage  lead  from  the  test apparatus   to   the   winding   or   circuit   under   test.   When testing   stator   rotor,   all   windings   and   circuits   must   be securely   connected   to   ground.   When   testing   rotor,   all stator   windings   and   circuits   must   be   connected   to ground. (4)   Test. (a)   Turn   on   test   apparatus   in   accordance   with manufacturer’s   instructions,   after   making   sure   that the  initially  applied  voltage  will  be  not  greater  than 600  volts. (b)  The  test  voltage  then  shall  be  raised  uni- formly  to  the  required  maximum.  This  increase  shall be  accomplished  in  not  less  than  10  seconds  nor  more than   30   seconds.   The   maximum   test   voltage   for   rotor windings   shall   be   equal   to   1,000   volts   plus   twice   the highest   rated   voltage   of   the   generator.   The   test   volt- age  for  stator  windings  shall  be  equal  to  10  times  for exciter   ceiling   voltage   but   in   no   case   less   than   1,500 volts  nor  more  than  3,500  volts. (c)  Apply  the  maximum  voltage  for  1  minute. (d)  After  1  minute  of  applied  maximum  voltage, the   voltage   then   shall   be   reduced   gradually   to   the voltage   initially   applied.   This   reduction   shall   not   be accomplished   in   less   than   5   seconds. (e)  Turn  off  test  apparatus.  Ground  the  high- voltage  lead  of  the  test  apparatus  to  make  sure  that  no charge  remains  on  the  windings  which  have  been  under test. (f)   Remove   the   high-voltage   lead   from   the winding  and  proceed  with  the  tests  of  the  remaining circuits  to  be  tested.  Make  sure  that  all  circuits  not under  test  are  securely  grounded. 8-4 Change  2 (5)   Results, down   is   cause under   test. Any   evidence   of   insulation   break- for   replacement   of   the   equipment f.   Winding   Resistance   Test.   Perform   winding   re- sistance   test   using   a   Wheatstone   bridge.   Follow   the manufacturer’s  instructions  given  on  the  bridge.  Re- sistance   reading   should   be   36   ohms   ±3.6ohms.   Check resistance   between   each   lead   and   frame.   A   low   re- sistance   shows   that   the   stator   is   shorted. g.   Testing   Exciter   Rotor.   Perform   winding   resis- tance  test  and  high  potential  test  per  MIL-STD  -  705A, methods  401.1  and  302.1.  Test  between  T₁- T₂,  T₂- T₃,  T₁T₃.   See   figure   6-2   for   location   of   test   points. Resistance  for  each  winding  should  be  0.6’77  ohms  ± 0.067   ohms.   Also   test   for   shorts   between   windings and  between  each  winding  and  rotor  core. h.   Testing   Generator   Stator. (1)   High   Potential   Test.   Test   generator   stator   as given   in   paragraph   8-2e   of   this   manual.   Replace stator   having   faulty   insulation. (2)  Winding  Resistance  Test.  Perform  winding  re- sistance   test   using   a   Kelvin   bridge.   Follow   the   manu- facturer’s   instructions   given   on   the   bridge.   Resis- tance  readings  should  be  made  on  the  pins  of  P9  and P10   (see   figure   8-3).   Resistance   between   lead   pairs T₁-  T₄,   T₂-  T₅,   T₃-  T₆,   T₇-  T₁₀,   T₈-  T_1l  a n d    T₉-  T₁₂ should  be  0.115  ±  0.112  ohms  at  77°  F  (25”  C)  for  the MEP-003A.   For   the   MEP-l12A,   resistance   should be  0.071  ±  0.007  ohms. Refer  to  the  table  in  figure 8-3   for   location   of   the   terminals. Also   check   resistance   between   each   pin   A   through   F of  P9  and  P10  and  the  stator  frame.  Low  resistance indicates   a   shorted   stator. i.   Testing   Generator   Rotor. (1)  High  Potential  Test.  Test  generator  rotor  as given  in  paragraph  8-2e  of  this  manual.  Replace  rotor having   faulty   insulation. (2)   Winding   Resistance   Test.   Perform   winding resistance   test   using   a   Wheatstone   bridge.   Follow   the manufacturer’s  instructions  given  on  the  bridge.  Re- sistance   reading   should for   the   MEP-003A   and MEP-112A. Check   resistance   between resistance   indicates   that be  3.31  ohms  ±  0.33  ohms 3.05  ±  0.305  ohms  for  the each  lead  and  frame.  A  low the  rotor  is  shorted,  a  high resistance  indicates  open  winding.