Diesel Generator Fault Levels

I have a feeling that you have forgotten the poor old engine. The alternator fault levels are at infinite driving torque, but your average engine cannot provide this. The instantaneous fault level is controlled by the rotating mass (alternator and flywheel) but does not last very long (a few cycles at best). The front end CPDs of full generator rating will probably never open the circuit, even with a PPP fault (which is extremely unlikely). What will happen is the engine will stall as even at full torque it cannot support the virtually infinite torque required. Remember that engine torque at zero speed is nearly zero, and you only get sensible figures at somewhere near the normal operating speed. Engine maximum power output means exactly that, any overload which reduces speed also reduces the power available, so damage from short circuits is usually unlikely, whereas long sustained slight overload causes severe overheating.

I have a feeling that you have forgotten the poor old engine. The alternator fault levels are at infinite driving torque, but your average engine cannot provide this. The instantaneous fault level is controlled by the rotating mass (alternator and flywheel) but does not last very long (a few cycles at best). The front end CPDs of full generator rating will probably never open the circuit, even with a PPP fault (which is extremely unlikely). What will happen is the engine will stall as even at full torque it cannot support the virtually infinite torque required. Remember that engine torque at zero speed is nearly zero, and you only get sensible figures at somewhere near the normal operating speed. Engine maximum power output means exactly that, any overload which reduces speed also reduces the power available, so damage from short circuits is usually unlikely, whereas long sustained slight overload causes severe overheating.