NOTE The  output  voltage  may  exceed  the rating   of   connected   equipment. (k)  Record  all  instrument  readings  (after ransients  have  subsided). (l)   Apply   rated   load. (m)   Record   all   instrument   readings   (after ransients    have    subsided). (n)   Adjust   voltage   to   the   minimum   specified value  at  rated  load. (o)  Record  all  instrument  readings  (after transients    have    subsided). (p)   Remove   load. (q)  Record  all  instrument  readings  (after transients   have   subsided). (r)   Adjust   voltage   to   the   minimum   attainable value  or  a  value  just  prior  to  activation  of  the  under- voltage    protection    device. (s)   Record   all   instrument   readings   (after transients   have   subsided). (t)   Repeat   steps   (a)   through   (s)   above   for all   other   voltage   connections). d.   Sample   Calculations. Regulation   (droop)   is defined  for  the  purposes  of  this  method  as  the  no- load  value  minus  the  rated  load  value  divided  by  the rated   load   value   the   quantity   expressed   in   percent. % Regulation = (No-Load  Voltage)  -  (Rated-Load  Voltage)  x   100 (Rated -Load Voltage) e.   Results.   The   data   sheets   shall   indicate   the voltage   regulation   as   a   percent   of   rated   voltage   with- in   the   specified   limits   at   the   minimum   and   maximum specified   voltages   and   the   regulation   as   a   percent   of rated   voltage   at   the   extremes,   the   maximum   and minimum   voltages   attainable   and   the   actuation   of   the protection   devices   (if   applicable).   Compare   these results   with   the   requirements   of   Table   16-1. 16-15. Frequency   and   Voltage   Regulation,   Stability and   Transient   Response   Test   (Short-Term). a.   General. The    frequency    regulation    (sometimes referred   to   as   droop)   of   a   generator   set   is   the   maxi- mum  difference  between  the  no  load  value  of  frequency and  the  value  at  any  load  up  to  and  including  rated  load. This   difference   is   expressed   as   a   percentage   of   the rated   frequency   of   the   generator   set.   The   voltage regulation   is   expressed   similarly   except   that   the   rms value  of  voltage  is  used. Frequency   stability   describes   the   tendency   of   the frequency   to   remain   at   a   constant   value.   Generally, the   instantaneous   value   of   frequency   is   not   constant but  varies  randomly  above  and  below  a  mean  value. Stability   may   be   described   as   either   short-term   or long-term  depending  upon  the  length  of  time  that  the frequency   is   observed. Another   term,   bandwidth, describes   the   limits   of   these   variations.   Bandwidth is   expressed   as   a   percentage   of   the   rated   frequency of   the   generator   set. Voltage   stability   is   described similarly. Frequency   transient   response   describes   the   reaction of  the  frequency  to  a  sudden  change  in  some  condition; such   as,   a   load   change   on   a   generator   set.   This   re- sponse  consists  of  the  amount  of  excursion  beyond  the mean  of  the  new  operating  band,  and  the  recovery time.   The   recovery   time   is   the   interval   beginning   at the   point   where   the   frequency   leaves   the   original prescribed  operating  band  and  ending  at  the  point where   it   enters   and   remains   within   the   new   prescribed operating   band. The   amount   of   surge   is   expressed as  a  percentage  of  the  rated  frequency  of  the  genera- tor   set. The   recovery   time   is   expressed   in   seconds. The   voltage   transient   response   is   described   similarly. b.    Apparatus. Instrumentation   for   measuring load   conditions,   field   voltage   and   current,   and   ambient temperature  shall  be  as  described  and  illustrated  in MIL-HDBK-705.  In  addition,  recording  meter(s)  for recording   voltage   and   frequency   shall   be   required. The   recording   meters   shall   be   as   described   in Table   2-1. c. Procedure. (1)   Preparation   for   test. (a)   Connect   the   load   and   field   instrumenta- tion  in  accordance  with  the  applicable  figure  of MIL-HDBK-705,    Method    205.1,    paragraphs    205.1.10, for   one   voltage   and   frequency.   Connect   the   signal input   of   the   recording   meter(s)   to   the   convenience receptacle  of  the  set  or  to  the  generator  coil  which  is used  as  the  voltage  sensing  input  to  the  voltage  regu- lator. (Power   the   recording   meter(s)   from   the commercial    utility.) (b)   Set   the   recording   meter   chart   speed(s) to  a  minimum  of  6  inches  per  hour.  The  following items  shall  be  recorded  on  both  the  data  sheets  and recording   chart(s): 1.   The   date 2.   The   serial   number(s)   of   the   recording meter(s) 3.   Generator   set   identification 4.   The   recording   chart   speed(s) 5.   The   data   reading   number (c)   Place   all   instrumentation   referred   to   in paragraph    16-15b.    in    operation. 16-5