responding to
http://www.homeownershub.com/mainten...ge-708848-.htm
DA wrote:
HeyBub wrote:


http://www.newscientist.com/article/...lights-on.html

Wonder: How can Centerpoint distinguish between an a/c and a 240v
welding
machine? Or would they just cut both of them off?

I think the journalist writing that article had mixed two different things
together. A meter, smart or otherwise, is in series with the rest of the
loads in the house - never seen one installed specifically for an A/C
condenser unit. So, if it did have a large contactor in it (and it
doesn't), it would cut all the loads in the house, not just the outside
A/C unit.

The thing that does cut the A/C condenser unit off is called DCU (Digital
Cycling Unit). It gets installed next to and in series with the outside
A/C unit's own contactor and, when activated by the power company, ensures
that the A/C condenser does not get power for 15 min out of every 30.
Usually during peak demand hours. So, no worries about your welder unless
it's hooked up in parallel with the outside A/C unit and you're welding on
a hot weekday afternoon in the summer.

DCU is a preventive measure, BTW. They are too slow to react to save the
grid from a blackout that's already on the way. Also, I would not call
them a part of a "smart grid" either - they are more like a part of the
A/C appliance, sort of like crutches that save the power company from
actually upgrading their grid equipment. Says Peco about their Smart A/C
Saver DCUs: "Keep in mind that the primary purpose of the program is to
balance the demand for electricity to minimize the potential for power
outages and reduce the need for costly infrastructure additions."

Cheers!

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