Re: generators 4 poles switching
Chuck, you have the sequence right on a fault in the emergency position on non-SDS, but consider this. Suppose you are testing the generator with load, and a fault were to occur in the generator. You would trip both the generator and service GFP?s at the same time.. That would be false trip of the service even though it didn't occur in the service.
The only way to prevent it is to configure the generator as SDS and switch the neutral if used. This will prevent any false or nuisance tripping of GFP in either source.
Here is my design philosophy: If a generator is permanently installed on site and/or the service has GFP, install the generator as SDS. If the generator is going to be portable and the service has no GFP, then the generator can be configured non-SDS. If a generator is configured SDS, then the ATS has to switch the neutral if it is used.