On India's power outage

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An overview story. But buried in the story is this:
"But progress is being made. CenterPoint Energy, a regional utility company based in Texas, is in the final stages of constructing a network of smart meters across the city and suburbs of Houston. By 2013, 2 million smart meters will track energy use in Texans' homes, and allow CenterPoint to turn off air conditioning units during times of high demand for instance, although CenterPoint admits it will need customer consent for this."
http://www.newscientist.com/article/dn22140-power-struggle-how-to-keep-indias-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?
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wrote:

They have to add a switching device to the circuit going to your A/C. (water heater or whatever)
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On 8/8/2012 9:17 AM, snipped-for-privacy@aol.com wrote:

And our utility started doing power line signalling like that a long time ago when they were promoting onsite thermal storage. You got a really cheap rate for power and you wired a similar module to what you get now into the control circuit. They could take the heating elements offline anytime they needed.
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On 8/8/2012 8:17 AM, snipped-for-privacy@aol.com wrote:

I don't know if it's still offered but Alabama Power installed a radio controlled cutoff unit on customer AC condensers that would interrupt the 24volt current to the contactor in the outdoor unit whenever the power company had a big demand and transmitted the cutoff signal. I don't know if it was for a certain period of time or what but it's been about ten years since I last noticed one on an air conditioner. ^_^
TDD
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On Wednesday, August 8, 2012 3:41:55 AM UTC-7, HeyBub wrote:

It’s another reason for the HVAC technicians to charge more money. Now when you go to do repairs you have to figure out if the unit is shutting down due to one of the fan motor thermal cut-offs, low pressure or the SaverSwitch.
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On Wed, 8 Aug 2012 07:35:18 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

I had this system in my condo in Treasure Island. There was an LED in the controller that went from green to red when the utility was shutting down the power.
The only thing that is different is the new meter gets the signal; and WiFi's it to the local controller.
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On Aug 8, 1:36 pm, snipped-for-privacy@aol.com wrote:

I have it here in NJ too with no smart meter. IT's a radio controlled switch at the compressor unit. Have had it for 20 years now. They used to give us a flat amount, like $25 a year for having it. Now they switched to giving out $2 every time they activate it. They rarely activate it, so I'm not getting much anymore.
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On 8/8/2012 12:43 PM, snipped-for-privacy@optonline.net wrote:

Alabama Power offered the same thing to customers at one time but I haven't seen one in years. ^_^
TDD
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On Wednesday, August 8, 2012 10:36:38 AM UTC-7, (unknown) wrote:

Usually by the time anyone in the house realizes that the A/C may not be running it is back on again so they’re not sure if there was a problem with the unit or if it was turned off by the utility.
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I guess not many people know that about 8% of males are red green color blind. Something like that.
Christopher A. Young Learn more about Jesus www.lds.org .
I had this system in my condo in Treasure Island. There was an LED in the controller that went from green to red when the utility was shutting down the power.
The only thing that is different is the new meter gets the signal; and WiFi's it to the local controller.
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On 8/8/12 9:35 AM, snipped-for-privacy@gmail.com wrote:

The rural power companies here in Nebraska use something similar on irrigation wells. The electronics control some sort of relay. It's easy to bypass the relay for troubleshooting. It's only a problem if the power controller is causing intermittent shutdowns.
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responding to http://www.homeownershub.com/maintenance/on-india-s-power-outage-708848-.htm DA wrote: HeyBub wrote:

http://www.newscientist.com/article/dn22140-power-struggle-how-to-keep-indias-lights-on.html
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!
------------------------------------- /\_/\ ((@v@)) NIGHT ():::() OWL VV-VV
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http://www.newscientist.com/article/dn22140-power-struggle-how-to-keep-indias-lights-on.html
The home is divided into essential and non-essential circuits.
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I can see that system working, based on my own experience with AC. Short down times are not a big deal. Many people keep the house cooler than it has to be and a brief time down makes no discernable difference.
Recently, on a pretty hot day, there was a quick power outage. My AC went off, came back on but not in the "cool" position. It took about an hour before I finally noticed that it was getting overly warm. If the power company has shut it down for five of twenty minutes, I never would have noticed.
In the case of your sister's house, the system is either not sized properly, not laid out properly, or not installed properly. The technology to have a well balanced system has been around for decades. Unfortunately, things like this happen.
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I don;t know about that. An AC system is supposed to be sized so that it runs most of the time on the hottest days. If the power company then turns it off so it can't run as much as it needs to, it seems perfectly possible that some people could wind up with homes that are too hot.
Another way of looking at it is this. The power companies claim that it makes no difference in the temp in your house. If that's the case, what good does it do the power company? All the AC units out there are already either randomly cycling because they can maintain the set temp or else just running all the time. If they are randomly cycling, then how do you reduce the load to the power company without reducing the cooling? If the ACs were all coming on and off at exactly the same time, then by fooling with then, the power company could even it out. But because they are already random, I don't see what they are doing having any effect unless it raises the temp in the house. And if the AC is running 100%, then for sure turning it off for 10 mins is going to decrease the cooling output.
And if it starts doing that, if you have a multi-story home with a single system, I would think it could easily effect the upper levels to an unacceptable level.
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My guess is increasing the delta-T would make many of the ultra cold houses more in line with what they should be and that is at least part of the goal. I think the main goals is control at peak times. The power company will let yhour house get a little warmer during the peak and they don't care if it runs longer after industry shuts down around 4 and office close down around five. After that, they have the power available to bring your house down to 40 degrees if you want.

In a perfect world, there would be no imbalanced systems. Seems a shame to have to run a unit more than really needed to compensate for design flaws. Changing duct sizes and air handlers now is rather costly though. Even when a house is built, there are many ways to insure a perfect balance, but they can be costly. Buyers are reluctant to spend an extra $5000 up front to save a few hundred a year for life. Granite counter tops are more important than better insulation or better HVAC systems.
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Actually I think the problem is that BUILDERS THINK that homeowners won't spend some extra money for a correct HVAC install, so they never get the chance. Anyone who has had experience with a half-assed system would highly value having it done right. And I don't think it would typically cost an extra $5,000. Just simple things, like putting decent, large returns on the upper floors would go a long way. And to do that, it's just a design/layout issue, allowing space in the floor plan, eg a chase or similar to run the duct in. Absent a chase, the HVAC guys show up and are left with only wall cavities.
But even if it did cost $5K, I for one would much rather that then be uncomfortable for 15 years.
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On Thu, 9 Aug 2012 06:27:01 -0700 (PDT), " snipped-for-privacy@optonline.net"

Agree. When we bought our house in 2002, I asked and would have been happy to pay for an upgraded AC system, but it wasn't an option. They continually claimed (both the builder and the HVAC contractor who had sized and installed them) that the 2 ton unit was properly calculated for the house, even required to be that size by code, and tried various tweaks that didn't really help much (and they always came out at noon, when the undersized unit wasn't an issue). After sweltering and dreading every 98+ degree day of which we get dozens over the summer (it's a dry heat, really) knowing the house would be very uncomfortable from 4-11pm, for 8 years, we finally got some (other) contractors out and had it replaced with a 3 ton multi-speed system. Now I'm sitting inside a 73 degree house while it's 106 outside, and our electric bill is *much* less in the peak of the summer. I'd spend the $6000 again in an instant now in the same situation...
Josh
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wrote:

Typical guidelines for design.
http://www.kohlerandlewis.com/pdf/AirDesign.pdf Introduction It is important for building owners to understand the criteria by which air conditioning systems are typically designed. These criteria which have been established by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.) and are referenced by most energy codes.
This memo presents the typical design criteria and explains their ramifications. It also explains why air conditioning systems are not typically designed to cool rooms below 75°F and why they may not appear to work properly on very hot days.
What are the criteria for AC system design? l Indoor design temperature: 75°F l Outdoor design temperature: 85°-90°F l Outdoor relative humidity: 50%
What does this mean? What this means in practical terms is that a properly designed air conditioning system will cool a building to 75°F on a day when it is 85°-90°F outdoors with 50% relative humidity (the temperature varies depending on the geographic location of the building).
What are the consequences of these design criteria? It is important to understand the following: l The system is not designed to cool a building to less than 75°F on the hottest days. l If the outdoor temperature and humidity exceed 85°-90°F and 50%, the building or certain areas of the building may not be able to be cooled as low as 75°F. l Temperatures and humidity may exceed these values for several days at a time during a "hot spell".
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^^^^^^^^^^

I assume you mean *decreasing* delta-T. The problem with this is that the power company doesn't know what your delta-T is. The only thing they can do is increase delta-T for everyone, or do it randomly.

Yes, but turning the compressor off for twenty minutes (or whatever) on a rotating basis won't accomplish this.

Buyers are rarely given the choice and it really isn't something they can be expected to understand. Few would understand even the size of the units.
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