TM 5-6115-275-14 NAVFAC P-8-615-14 TO 35C2-3-452-1 deviates from the reference (mean   of   the   observed   band) frequency   value   determined   at the  beginning  of  the  long-  term stability test. Frequency excursion  is  defined  as  a  short- term, noncylic transient of a self- correcting nature.  The excursion shall   not   exceed   the   allowable band width by more than 1.5 cps. Transient performance Following any sudden increase in load   including   from   no   load   to rated load, the governing system shall   re-establish   stable   engine operating     conditions     within     4 seconds. The maximum transient frequency change below the   new   steady-state   frequency (undershoot)   shall   not   be   more than 3 per- cent of rated frequency.  Following any sudden decrease  in  load  including  from rated     load     to     no     load,     the governing system shall re- establish stable engine operating con-   ditions   within   6   seconds. The maximum transient frequency change above the new steady-state frequency (over- shoot)  shall  be  not  more  than  5 percent of rated frequency. (6) Voltage Performance. Voltage regulation The   voltage   regulation   from   no load to rated load and from rated load   to   no   load   shall   exceed three percent of the rated voltage for all connections except for the single-phase, 120/240V connection.  For the single-phase, 120/240V connection,    regulation    shall    not exceed 4 percent voltage. Steady-state regulation At constant loads from no load  to rated  load,  the  generator  terminal voltage   shall    not    deviate    more than  1/2  percent  from  its  average root mean square (rms) value. Transient voltage regulation Following any sudden load change   from   no   load   to   rated load  and  from  rated  load  to  no load, the instantaneous rms voltage will remain within a band width of plus or minus 20 percent of     the     no     load     voltage     as measured by a magnetic oscillograph    having    a    no-load voltage deflection of not less than 3-½    inches  (8.89  cm).    The  set shall re-establish stable operation within 2 seconds. Stable operation is operation within plus or minus one-half of one percent of rated voltage. s. Governor     System     Specification (Model MEP-023A). Frequency regulation The    governor    is    adjustable    to maintain frequency regulation not to exceed 3% with the frequency adjustment  constant.    Frequency regulation     is     defined     as     the difference   between   the   no-load frequency    and    the    rated-load frequency. Short-term steady-state stability The governing system auto- matically    maintains    the    short- term,   steady-state   frequency   of the   set   within   a   band   width   of +1/2 of 1% of the rated frequency at 1-18