Originally Posted by Cheechako
ac generators run at 3600 rpm
. That's screaming.
Most marine generators run at 30 times the desired frequency. The ones that run at 60X are not really that popular. They mainly appear in low end low power
units. The typical quality marine generator
runs at 1800/1500 RPM
for 60/50Hz output.
The idea that a DC genset is "self optimizing" is a bit of a myth in my opinion. Fixed speed 3 cylinder diesels last a long time. If you are worried about light loading then put a load on it. It does not change fuel consumption
much to load a genset to 30% of kW output which is enough to keep the engine
hot. It's pretty simple to build up a 200-300A mains powered charging
system that runs from a genset or shore power
It's pretty hard to beat the reliability
of a shaft connected AC generator. Some DC units have belt drives and somewhat complex engine
speed control circuits. And a lot of DC units have one or two cylinder shake-a-lot engines.
You will find people with bad AC genset experiences. But that has more to do with the vast market share they enjoy. There are hundreds of thousands in service
. If they were terrible there would be a lot less of them.