ELECTRICAL VOLTAGES AVAILABLE TESTING AND ADJUSTING line leads, called "Zig-Zag" will lower the nominal 60 Hz voltage  about  13%,  making  it  usable  as  a  400  volt  unit. Voltage   level   adjustment   range   remains   about   +5%. With a  zig-zag  connection,  the  excitation  level  at  60  Hz, 400 volts is essentially the same as it was at 50 Hz, 400 volts.    The   zig-zag   connected   generator   therefore   will retain   its   excellent   motor   starting   ability.      The   final connections are shown in Figure 6. Connect T1 to T8 T2 to T9 T3 to T7 Line Leads are T4, T5, T6 Neutral is TO If the zig-zag connected generators are to be operated in parallel or with other generator sets, additional line leads must     be     run     through     the     window     of     the     droop transformer  (3N1964).    This  is  necessary  to  retain  the correct   droop   transformer   voltage   relationship   when  a zig-zag connected generator is paralleled. Observe the  direction and the  number  of  T-8  line  leads coming  out  of  the  generator  and  passing  through  the transformer  window.    Also  observe  the  number  of  times the   T-8   lead   (or   leads)   pass   through   the   transformer window.      An   equal   number   of   T-2   leads,   must   pass through  the  window  the  same  number  of  times,  and  in the same direction as the existing T8 leads.  The end of T2 is then connected to T9 as shown in Figure 6. On   some   generators   the   droop   transformer   will   not accommodate    the    additional    line    leads    through    the window.    Instructions  for  the  necessary  conversion  are shown in Figures 7 and 8. Correctly   connected   zig-zig   generators   will   operate   in parallel.    In  single  or  parallel  operation,  the  50  Hz  kVA ratings   would   generally   apply   to   a   zig-zag   connected generator operating at 60 Hz. Zig-zag    connections    (with    proper    droop    transformer modification  if  parallel  operation  is  expected)  may  also be  applied  to  a  480  volt  50  Hz  generator  to  cause  it  to produce  420  volts  at  50  Hz.    The  original  line  ampere rating  of  a  480  volt  50  Hz  generator  would  apply  to  the unit   when   operated   at   420   volts.       kVA   capacity   is reduced 13%.  Modified units will operate in parallel. There    are    other    areas    of    the    world    where    60    Hz generator  sets  are  now  used  as  prime  power,  but  these may eventually be required to  serve  in  a  standby  system  when  commercial  50  Hz power becomes available, or is required by governmental  decree.    In  these  instances  the  oncoming or future power system will probably be one of the above listed   common   50   Hz   three-phase   voltages   (i.e.,   380, 400,  or  415).    As  noted  previously,  a  60  Hz   480   volt generator   will   produce   400   volts   at   50   Hz.      Normal voltage level adjustment range of the SR 4 Generator is adequate   to   meet   the   lower   and   upper   limits   of   the probable future voltages. Figure 6 Zig-zag  connection  to  obtain  420  volts  from  a  480  volt generator    or    87%    of    normal    volt    from    any    SR    4 Generator.  For parallel operation, the droop transformer must enclose 1-leads as shown.  Note the direction of T2 through  transformer  and  the  connection  to  See  Figure  7 for  detail  when  droop  transform  will  not  accommodate additional line leads. The following generators require installation of a second 3N1964     Droop     Transformer     to     provide     space     for additional  line  leads  necessary  for  operation  of  zig-zag connects SR 4 Generators in a parallel system. 5N2 5N24 5N36 5N146 5N6 5N5 5N28 5N37 5N57 5N6 5N6 5N29 5N39 5N58 5N13 5N33 5N40 5N59 5N23 5N34 5N42 5N61 97