My concern was the unbalanced load. possibly putting an un due strain on the motor, and cutting its expected life.
Most 3-phase generators are designed to handle 100% imbalance, but must be derated; you're not going to get 50kW out of a 50kW 3-phase generator if you only use one phase, you're going to get about 28kW. The engine doesn't care, and the generator is just cables on a rotor, which is still balanced from an electromechanical standpoint. There's really nothing electrically or mechanically damageing about it aside from running the engine at less than half load all the time, and all the bad things that happen when you run a lightly loaded diesel engine too long.
