TROUBLESHOOTING TESTING AND ADJUSTING TROUBLESHOOTING GENERAL Before  working  inside  the  generator, make  sure  that  the  starter  motor  can not  be  activated  by  any  automatic  or manual signal. When the engine-generator is operating,   voltages   up   to   240   are present    on    the    regulator    terminal board.      The   heat   sinks   and   other regulator components have an electric  charge.    Components  will  be damaged  if  a  metal  contact  is  made between the generator frame and the heat   sinks   or   other   regulator   parts. Safety procedures must be followed. A  large  percent  of  the  electrical  problems  are  caused by  mechanical  defects.    Take  time  to  carefully  inspect the   total   installation.      Keep   the   mechanical   defects separate from the electrical defects. For  practical  purposes.    the  generator  is  a  constant speed unit.  RPM that is 5 to 10 percent higher or lower than  the  rated  rpm  can  cause  terminal  voltages  that  are 5 to 10 percent higher or lower than the rated output. Generator  heat  is  caused  by  line  current.    The  higher the line current, the hotter the generator will become. A   voltmeter   and   ammeter   or   KW   meter   does   not necessarily  show  the  KVA  load  on  a  generator  because of the power factor of the load. Before    working    on    the    generator,    be    sure    you understand the operating principles. Find  the  operating  trouble  and  use  the  wiring  diagram and troubleshooting guide to find the probable cause. When   troubleshooting   for   voltage,   a   generator   can normally   be   operated   at   a   low   rpm.      Voltage   and frequency will change directly with rpm.  A four-pole, 60 Hertz, 240 volt, 1800 rpm generator at a low idle of 1200 rpm will have an output of 160 volts at 40 hertz. NOTE:    For  information  on  mechanical  and electrical  characteristics  of  SR  4  generators, make  reference  to  the  section  INDUSTRIAL DIVISION DATA SHEETS:  No.  70.0.1 and the TECHNICAL INFORMATION FILE (TIF). TEST INSTRUMENTS A  volt-ohm-milliammeter  with  scales  of  approximately the following values: AC volts  ........................... 0-12, 0-100, 0-300 DC volts  ........................... 0-50, 0-100, 0-150 Ohms  ........................... XI, X10, X100, X1000 DC Amps.................................................. 0-3 The  6V3030  Digital  Multimeter  can  also  be  used.    By itself or with other tools, it can do the following: 1. Test rectifiers with the special diode function. 2. Measures  resistance  of  the  revolving  field  and stator    winding    of    the    generator    or    exciter winding. 3. With     the     6V4960     AC     Current     Probe,     the multimeter   can   measure   current   in   the   range 10A to 1000A rms (at a circuit-to-ground voltage of 650 V rms maximum.) See Special Instruction,  Form  SEHS801  I  for  warnings  and more   information   on   how   to   use   the   current probe. 6V3030 DIGITAL MULTIMETER 52