example

[don_resqcapt19]

But if you have an SDS that transforms to another voltage, there has to be some statement which says the SDS output and associated wiring beyond the disconnecting means is a different system for the purposes of 300.3(C).

I realize we are not going to get anywhere in this debate because of said definition(s) or lack thereof. I just believe it's a noteworthy issue.

You have a valid point, but that is just not how the code is written.

PIs for the 2020 code are due in early November of 2017

 

[Smart $]

...
Still not sure how you'd pass upstream reactance through a magnetic field?

For example, where upstream reactance causes upstream voltage sag, such as during inrush events. Also, reactance will feed a downstream fault.

 

[GoldDigger]

The Sola constant vo ltage transformer (CVT) uses a weak coupling between primary and secondary magnetic circuits and then uses a tuned circuit and saturation on the secondary side to limit the voltage there.
Not easy to model or design.

 

[n1ist]

An MG set is another example of an SDS; we use a 208V 3ph motor to drive a generator for making 50Hz power to test gear going overseas.

 

[kwired]

An MG set is another example of an SDS; we use a 208V 3ph motor to drive a generator for making 50Hz power to test gear going overseas.

If the generator is interconnected to another system it may or may not be separately derived depending on how it is connected. If it's ouput system stands alone it is separately derived.

 

[Smart $]

If the generator is interconnected to another system it may or may not be separately derived depending on how it is connected. If it's ouput system stands alone it is separately derived.

The usual determining factor is whether or not the grounded [neutral] conductor is switched by the transfer equipment. If not switched,the genset is not separately derived.

 

[kwired]

The usual determining factor is whether or not the grounded [neutral] conductor is switched by the transfer equipment. If not switched,the genset is not separately derived.

Correct. If not interconnected to another system there is no transfer switch but it is still separately derived source from any other source on the premises. Tie a common conductor of two sources together and they become one system, same with transformers - they become auto transformers other then if all that is tied together is grounded conductors that otherwise don't ordinarily carry current between the two systems.