[aprssig] Shack backup power

Keith VE7GDH ve7gdh at rac.ca
Sun Jun 5 12:06:01 EDT 2011

Lee  K9WRU wrote...

> Well, Keith, not all transfer switches operate as you have described. 
> Mine, for example, switches only those circuits I have chosen to have active 
> under generator supply. And it is correctly wired!  If you think about 
> it, I'm sure you will see why this is the way it is done when the emergency 
> source is expected to produce less power than the normal full load. 

Transfer switches are supposed to ensure that it is impossible to connect
a generator to the grid. If the transfer switch doesn't accomplish that,
it's a potential death trap.

> You are correct in that the generator is never supposed to be connected
> to the line but given the nature of  residential wiring (including mine)
> which "grows over time" bad things can happen and I would certainly
> hate to guarantee that there is no "cross connection."

Bad things are not supposed to happen. Transfer switches are designed
to prevent a generator from being connected to the grid. I'm sure there
are installations done by homeowners and not by a certified contractor
and not inspected, but at the very least, the homeowner should ensure
that their installation meeds all code requirements, even if they didn't
take out a permit and get it inspected. Safety is paramount.

> And I will make my other point again. It is very easy for someone to 
> assume that if he has a solar panel and a grid tie converter he has 
> something that will supply power when the commercial system fails.

Someone that assumes they will always have power because they have
a grid tie inverter (not converter) are mistaken. When their grid tie
inverter is producing power, either they use the power themselves,
or it gets fed out to the grid. When the power goes off, they are in
the dark. Grid tie inverters shut down when it doesn't see the correct
voltage / frequency coming in from the grid.

>  It is a bit hard for me to understand how that will happen if the grid
> tie converter is part of the solar panel. As I said, it seems to me that
> people are being a bit too aggressively "green."

I doing think there is any such thing as "too green" but it is our grandchildren
that will see what happens when we "run out of oil". Of course, it isn't
an "energy" problem, it is an "overpopulation" problem.

73 es cul - Keith VE7GDH
"I may be lost, but I know exactly where I am!"

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