What are the conditions to be satisfied for parallel operation of DC generators?

Electrical Engineering Electrical Machines
1
  1. The polarities of the generators must be same or the connections must be interchanged till they become same.
  2. The voltages of both the generators must be equal.
  3. The change of voltage with change of load should be of same character.
  4. The prime movers driving the generators should have stable and similar rotational speed characteristics.
  5. The positive and negative terminals of generators must be connected properly to the positive and negative of bus bar.