The output impedance of a generator, and so the Zs and PSSC, is a function of the current throttle setting, and in turn varies with the load. It is quite possible to stall a lightly loaded generator without operating any MCBs or fuses.
I'm interested in why a lightly loaded genny should have a lower PSSC.
I would have thought that the instantaneous fault current depended on the inertia which doesn't change with load and the longer term fault current (more than 1 sec) would depend on how much spare capacity was left on the throttle so it would larger for low loads.
Large UPS systems also have this problem and maybe the answer is to have an undervoltage relay that senses the fall in voltage from a larger fault.
The output impedance of a generator, and so the Zs and PSSC, is a function of the current throttle setting, and in turn varies with the load. It is quite possible to stall a lightly loaded generator without operating any MCBs or fuses.
I'm interested in why a lightly loaded genny should have a lower PSSC.
I would have thought that the instantaneous fault current depended on the inertia which doesn't change with load and the longer term fault current (more than 1 sec) would depend on how much spare capacity was left on the throttle so it would larger for low loads.
Large UPS systems also have this problem and maybe the answer is to have an undervoltage relay that senses the fall in voltage from a larger fault.
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