Judge John P. Lavelle today set Tuesday, Nov. 20, 1979 as the date for the susbstituted Municipal General Election in Carbon County. The jurist handed down his order following a 45-minute hearing in the main courtroom of the Carbon County Courthouse. Judge Lavelle explained that the election, which was scheduled for Nov. 6, had to be invalidated and declared null and void for the reason that automatic voting machines used in the balloting process had been improperly set, thereby hampering the chances of a fair and equitable vote.