(c)   Prior   to   closing   the   short-circuiting switch,   record   a   portion   of   the   steady   state   load   for calibration.  With  the  same  load  conditions  record all   instrument   readings. (d)   With   oscillograph   still   recording   the steady   state   current,   close   the   short-circuiting switch. CAUTION If   the   circuit   interrupter   fails   to   operate within   the   specified   time,   remove   the short   circuit   to   prevent   damage.   Note the  failure  to  operate  on  the  data  sheet. (e)  The  generator  set  contains  a  short- circuit   malfunction   indicator,   check   and   record   its indication, (f)  Repeat  steps  (a)  thru  (e)  above  for  each possible   short   circuit   condition (g)  Repeat  steps  (a)  thru  (f)  above  for  both voltage   confections   if   applicable. d.   Results. (1)   From   the   oscillograms   taken   in   16-18c (2)(d),   determine   the   time   between   the   indicated closure   of   the   short-circuiting   switch   and   the   opening of  the  circuit  interrupter.  See  figure  512.1-110 (2)   Calculate   the   short-circuit   current   using the   peak-to-peak   amplitudes   of   the   current   trace   and the   steady   state   ammeter   reading   prior   to   applica- tion   of   the   short   circuit. See  figure  512.  l-II. (3)   Tabulate   the   above   results   and   the   m_al- function   indicator   indication   for   each   line   connection at   each   voltage   connection   and   compare   the   results with   the   requirement   in   table   16-1. 16-19.   Circuit   Interrupter   Test   (overload   Current) a.   General.   A   circuit   interrupter   is   connected bettween   the   generator   voltage   reconnection   system and   the   generator   output   terminals   to   disconnect   the generator  output  from  the  load  and  to  protect  the generator   from   a   sustained   overload   current.   The circuit   interrupter   is   operated   from   a   current   sensor external   to   the   interrupter. b.   Apparatus. Instrumentation   for   measuring load   condition   field   voltage   and   current   shall be   as   described   and   illustrated   in   MIL-HDBK-705. In  addition  a  stopwatch  or  an  oscillograph  with  gal- vanometer   matching   network   and   a   non-inductive shunt   as   described   and   illustrated   in   MIL-HDBK-705, Method   106.1,   paragraph   106.   1.3   and   galvanometers having  a  flat  frequency  respond  (within  plus  or  minus 5%  from  dc  to  3000  Hz. c.    Procedure. (1)   Preparation   for   test.   Connect   the   load   and field   instrumentation   in   accordance   with   the   appli- cable   figure   of   MIL-HDBK-705,   Method   205.1,   para- graph   205.1.10   for   one   voltage   and   frequency, CAUTION If   the   circuit   interrupter   fails   to   operate within   the   time   specified   in   table   16-1 at  any  time  during  the  performance  of this   method,   manually   open   the   circuit interrupter   and   reduce   the   load   impen- ance   to   rated   value   before   reclosing the   circuit   interrupter.   Record   on   the data   sheet   the   failure   of   the   interrupter to   operate   and   the   total   elapsed   time the  overload  was  on  the  set. (a)   Start   and   operate   the   generator   set   at   rated voltage;   rated   frequency   and   rated   load. (b)   Allow   the   generator   set   to   stabilize   at   rated load,   voltage   and   frequency,   During   this   period, readings   of   the   load   and   field   instrumentation   shall be   recorded   at   minimum   intervals   of   10   minutes. If   necessary,   adjustments   to   the   load,   voltage   and frequency  may  be  made  to  maintain  rated  load  at rated   voltage   and   frequency.   Adjustment   to   the   load, voltage  or  frequency  shall  be  noted  on  the  data  sheet. Stabilization  will  be  considered  to  have  occured  when four   consecutive   voltage   and   current   readings   of   the exciter   field   either   remain   unchanged   or   have   only minor   variations   about   an   equilibrium   condition   with no   evident   continued   increase   or   decrease   in   value after   the   last   load,   voltage   or   frequency   adjustment has  been  made. (c)   In   one   step,   increase   the   load   current   to the   overload   current   value   specified   in   table   16-1 (the   increase   in   current   may   be   accomplished   by any   practical   means,    e.   g.   reactively   or   using   re- duced   voltage   levels). NOTE The   frequency   shall   be   maintained   at   rated conditions,   the   load   current   shall   be   kept constant   and   the   load   current   shall   be   bal- anced   equally   among   the   phases.   Simul- taneously   with   the   load   current   increase, start   the   stopwatch. (d)   Record   all   load   instrumentation   and   the time,   m   seconds,   required   for   the   circuit   interrup- ter  to  operate. (e)   The   generator   set   contains   an   overload malfunction   indicator,   check   and   record   its   indi- cation, (f)  Allow  the  generator  set  to  cool  at  rated  load for  a  minimum  of  15  minutes. 16-10