(c)  Open   the   switch   and   adjust   the   resis- tance,   R2   until   Voltmeter   Number   2   reads   the   under- voltage   value   specified   in   Table   16-1.   This   test   shall be   repeated   for   each   undervoltage   value. c. Procedure. (1)   Preparation   for   test.   With   the   set   not   oper- ating   remove   the   protective   device   tap   from   the   en- gine-block  and  reconnect  as  shown  in  figure  515.  1-I with   the   protective   device   and   oil   pressure   gage   in approximately   the   same   horizontal   plane   as   the   pro- tective  device  tap  located  on  the  engine. (d)  Repeat  steps  (b)  and  (c)  above  to  assure that   the   specified   undervoltage   and   rated   voltage   set- tings   are   correct. (e)   Set   the   oscillograph   chart   speed   such that   the   individual   waveform   peaks   are   clearly   visible. Set  the  timing  lines  to  a  minimum  of  0.  01  seconds  per line   or   usc   a   60   Hertz   timing   trace.   With   the   switch open,    adjust   the   trace   peak-to-peak   amplitude   to   a minimum  of  one  inch  (or  25  millimeters). (2)   Test. (a)  With  the  bleeder  valve  closed  and  the shut-off   valve   in   the   oil   pressure   line   open,   start   and operate   the   set   at   rated   speed   (use   the   set   instrumen- tation)  and  at  no  load. (f)  With  the  set  operating  and  the  circuit interrupter   and   the   switch   open,   read   and   record both    voltmeter    readings. (b)  Open  the  bleeder  valve  slightly  to  purge air   from   the   system. (c)  Close   the   bleeder   valve   and   record   the oil   pressure   as   indicated   on   the   external   gage. (g)   Close   the   switch   and   circuit   interrupter, (h)   With   the   oscillograph   recording,   open the   switch, (d)   Almost   completely   close   the   shut-off v a l v e . (i)   After   allowing   sufficient   time   for   the circuit   interrupter   to   operate,   check   and   record   the indication   of   the   undervoltage   malfunction   indicator. (e)  Slowly  open  the  bleeder  valve  until  the low   oil   pressure   protective   device   shuts   down   the engine. Record   the   reading   of   the   oil   pressure   gage at  the  point  of  set  shutdown  (see  figure  515.  l-II). (j)  Close   the   switch,   and   close   the   circuit interrupter. (f)  Record   operation   of   the   malfunction   in- dicator   light. (k)  Repeat  steps  (e)  thru  (j)  above  two  ad- ditional   times. d .  Results.  Compare   the   value   of   shutdown   pres- sure   with   the   requirement   of   Table   16-1. (l)  Repeat  (a)  thru  (k)  for  the  other  under- voltage   value   specified   in   para.   16-1. 16-22.    Overtemperature    Protective    Device    Test. e. Results. a. General.    The   overtemperature   device   must be   capable   protecting   the   engine   in   the   set   against overheating   for   any   reason. (1)   From   the   oscillograms   made   in   16-20c determine   and   tabulate   the   time   between   the   appli- cation   of   the   overvoltage   and   operation   of   the   circuit interrupter   for   each   application   of   overvoltage. b.   Apparatus. Instrumentation    for    measuring    load conditions   and   set   and   ambient   temperatures   shall   be as   described   and   illustrated   in   MIL-HDBK-705, Method   205.1,   Paragraph   205.1.10. (2)   From   the   oscillograms   made   in   16-20d determine   and   tabulate   the   time   between   the   application of  the  undervoltage  and  the  operation  of  the  circuit interrupter   for   each   application   of   undervoltage. c. Procedure. (1)   Preparation   for   test. (3)   Compare   these   results   with   the   require- ments  of  table  16-1. (a)   Connect   the   load   instrumentation   in   ac- cordance  with  the  applicable  figure  of  MIL-HDBK-705, Method   205.1,   Paragraph   205.1.10. 16-21.   Low   Oil   Pressure   Protective   Device   Test. a.   General.   Since   generator   sets   frequently   oper- ate–unattended   for   long   periods,   the   engine   is equipped   with   a   low   oil   pressure   protective   device. This  device  shuts  down  the  engine  when  the  oil  pres- sure   drops   below   the   safe   limit. (b)  Install   a   thermocouple   to   measure   the same   temperature   as   seen   by   the   protective   device sensor. (2)   Test. b.   Apparatus. The  following  equipment  shall  be required   to   perform   this   test. (a)   Start   and   operate   the   generator   set   at rated   voltage,   rated   frequency   (speed),   and   rated   load. Oil pressure gage (± 1%) Flexible  oil  line  (or  copper  tubing) Regulating   valves Brass   fittings. (b)  Block  the  cooling  air  to  the  generator  set by   any   suitable   means. 16-12