Whole House Power Monitoring Board

[Beamer]

A recent discussion ([topic="9509"]here[/topic]) about power metering really got my gears turning. In particular, there were two products mentioned that I liked. The Energy Detective is pretty slick and affordable at $150, but for a HA geek like me (and probably the rest of you) it doesn't do quite enough. Then there is the WattNode, which does a lot more but costs $500. My reaction was to think that I could probably build my own WattNode for a TED price. After some mental schematic drawing and parts researching, I'm a little under $100 for cost of parts (including the two current transformers, something the WattNode didn't include!). Some features I expect to include at a minimum are: Vrms, Irms, Vpeak, Ipeak, Real Power, Reactive Power, Apparent Power, Power Factor, Crest Factor, Line Frequency, and integrated over time you could also get kWh and $$$. The board will also have a built-in power supply and an electrically isolated RS-485 interface with a jumper selectable terminator. That's what's on my mind so far...

Now the part where you guys come in... If you could own/design one of these, what would you have it do? I'd really like to hear your input before I call it final and make a PCB. Plus if it works pretty good I imagine I could put the schematic on here, and/or sell a preassembled version if you don't like to solder. This forum is full of great ideas, so I'd love to hear what comes to mind.

Some other things I've considered adding:
A temp sensor (or maybe just a generic 1-wire port?)
A couple of digital inputs and outputs
A remote display (but I really stink at making pretty boxes)

This is pretty much a spare time project (aren't they all), so I can't say when I'll finish, but I'll keep you posted. Thanks for the suggestions!

Brian Rondeau

 

[nsisman]

Brian,

Up here in the north ( and probably you too) we are being switched over to TOD rates (time of day) which basically sets 3 rates at different times thru the day (low, mid-peak and peak)

These rates can change a couple of times a day and they also change spring and fall but not necessarily with daylight saving changes.

Important to me would be charting or screens of data to capture KWH and $$$costs for "now" " last hour" "last day" "last week" "last month" plus "today's" " this hour" "this week" "this month".

Also we should be able to reset for new billing cycles etc.

You might want to check out the "powercost monitor" device as well as it doesn't require an in-panel hookup - everything mounts on the meter somehow.

Others I am sure will have different ideas !

Thanks

 

[politics123]

So, I realize that I'm probably way too early, but "When can I buy one?"

In the ideal world, energy usage would be graphed over time against environmental factors (eg: temperature, zone status -- open doors!, etc) but would allow "alarms" based on consumption, trendm and other status.

For example:
send me an email when consumption exceeds XYZ and my house is alarmed in away/vacation mode
-- "oops, I left the lights on, let me have my automation controller turn them off"
-- "oops, maybe I should adjust the thermostat since I'm not home"

For inspiration, check out these guys, who have very, very slick real-time environmental monitoring.
http://welserver.com/WEL1000/
http://welserver.com/WEL0043/

They use hardware/software/web-site provided by this guy: http://www.welserver.com/index.htm
I'm working on duplicating this work (but I want to spend less than $400 doing so)

Different Systems

• METER + CT http://www.energymonitor.com/
• WATTNODE (pulse output) http://www.ccontrolsys.com/products/pulse_output.html
• TED http://www.theenergydetective.com/index.html
• ANYONE CAN INSTALL IT (METER MOUNT) http://www.bluelineinnovations.com/
  (this last one is fantastic... it is inexpensive, either reads the infrared pulse for a digital meter or the black line for a traditional meter (installs in moments), and has a digital readout... unfortunately, it does NOT have logging ability)
• HOME BUILT http://www.btinternet.com/~jon00/electmon.shtml

I went the HOME BUILT route, with about $20 worth of parts. It actually does read the infra-red pulses from my digital meter, but I haven't done the rest of the work to read the data into a database for time-based graphs.


One advantage I see of having lower cost meters is to essentially sub-meter portions of the house. I have an electric hot-water heater and an electric heat-pump, and I'd love to monitor how much power they actually consume compared to the rest of my power bill.

 

[upstatemike]

Now the part where you guys come in... If you could own/design one of these, what would you have it do? I'd really like to hear your input before I call it final and make a PCB. Plus if it works pretty good I imagine I could put the schematic on here, and/or sell a preassembled version if you don't like to solder. This forum is full of great ideas, so I'd love to hear what comes to mind.

Brian Rondeau

I think the core features I would be looking for in a power monitoring system are:

-Standard tracking of power used for the month expressed in cost (monthly usage to date and bill prediction)

-Ability to have current sensors on certain sub-circuits (such as the electric oven) to warn that it is on and track its power consumption

-Ability to load my Stargate with a variable value for power use (in dollars and cents per hour) so I can set a threshold and have verbal warnings about high power usagae that speaks the current cost per hour.

 

[BraveSirRobbin]

What current and voltage sensors are you planning on using? Would you be "counting" the pulses or some type of analog to digital conversion?

This sounds like a great project!

 

[lazyone]

The board sounds like a great design and should give you what you need as far as measurement.

I would suggest at least 4 CT inputs, this would allow for a standard 320A service with two 200A panels. Personally, I would like to see about 8 CT inputs. Then you could meter 2 panels and 4 individual loads. A 1-wire interface would be useful as well.

Ideally, the RS-485 interface would be directly compatible with Elk's 485 protocol. Then, you could directly connect to their RS-485 bus. If connecting to a PC through a RS-485 to RS-232 converter, you will need some sort of interface driver and/or software.

As far as software is concerned. I would love to see a nice time/tag based historian database with good graphing capabilities. We have them in the Industrial manufacturing industry ($$), but I have not seen anything close to what I want in Home Automation software.

Good luck on the PCB.

lz

 

[klindy]

[*]HOME BUILT http://www.btinternet.com/~jon00/electmon.shtml
[/list]I went the HOME BUILT route, with about $20 worth of parts. It actually does read the infra-red pulses from my digital meter, but I haven't done the rest of the work to read the data into a database for time-based graphs.

I'm using CQC and have a 'datalogger' driver which should be able to handle the database stuff and graphing. I really like this idea!

 

[WayneW]

ramblings/opinions:
I don't like pulse output, I want real time updating every second or two.
Your device doesn't need a display as all geeks will use a PC for displaying and graphing. But an optional stand-alone display may be appreciated by some.
Alarms, graphing, pricing, billing should all be handled by the PC for max flexibility. We just need an interface box to provide serial numeric data.
But the unit should have enough on board memory to log for "a while". This could be as short as 10 minutes (long enough to reboot your PC).

Is an RS-485 interface needed? Or is RS-232 cheaper & easier? I don't think this belongs on the Elk bus as nothing should compromise security and the Elk cannot graph.

Anything that attaches to the power meter (counting revs or blinking LEDs) won't work for me as my meter has nothing but a numeric LCD display. I prefer CTs and lots of them.
I would love multiple channels (i.e. multiple CTs) to monitor sub circuits. This gives you a way to monitor major appliances, lighting, HVAC, electric water heaters, pool pumps, etc. Maybe a daughterboard or modular approach would let users add as many CTs as needed without adding cost to everyone.

Drawbacks of the TED are that its wireless design interferes (for many) with X10 & Insteon (dunno about UPB) and that it requires the PC 100% of the time for logging.
The Wattnode with pulse output doesn't provide much info. With the LONworks interface, it has lots of options, but is expensive.

Other systems to study:
http://www.brandelectronics.com/onemeter.html allows monitoring multiple loads/circuits, but they charge to reconfigure the unit and won't give me their serial command protocol. ($400 and up)
http://ezmeter.com/ no sub-circuits
http://www.trendpoint.com/EnerSure.html ($1000 and up)

 

[upstatemike]

I have always liked this interface for looking at power usage etc.

 

[drozwood90]

If connecting to a PC through a RS-485 to RS-232 converter, you will need some sort of interface driver and/or software.

Not so. I have used 232-485 converters quite extensively. If you run (as I think the Elk is) 422ish 485 (5 wire) you just level shift the 232 to 485 levels AND make it differential. If you run 232 to TRUE 485 (3 wire), then you need to level shift AND use hardware flow control.

Beyond that, anything that sits on top (Elk protocol/Pelco/Bosh/Token Ring/Etc.) is up to the MFTR. There really is NOT a 485 protocol. Even at that, people generally mistake 485 for being full duplex. It's not. 422 is. The main difference between 422 and 485 is that 485's electrical specs. allow you to hook multiple devices into the same line. 422 is SUPPOSED to be point to point (as RS232 is). However, MOST chip MFTRs out there now make 422/485 compliant chips. So, they took the benefits of BOTH technologies (isn't advancement of CMOS technology great!??) and blended them together.

This is generally what makes it so easy for people to get mixed up, or not understand 485 != 422, but most companies claim 485 on their system...but really it's 422.

Long story short, you can just get a 422/485 converter board, hook up 5 wires, and run it 1 mile (actually the standard allows for much farther and faster rates, but the longer the cable the slower you need to run. I think under 10 feet on 422 is 30meg/sec., and out at 3-5 miles it's 300-1200baud, so under 1 mile, 115,200baud is perfectly fine).

http://www.commfront.com/RS232_Examples/CC...es_Tutorial.HTM
That's not a direct link, but that company makes a few

--Dan

 

[SteveQ]

Brian,

I am approaching the whole issue of power usage and conservation from a different direction. Rather than monitoring the power consumption of the whole house or subs within the house, I am tracking the actual run time of my major energy users. I find this to be a better way to make decisions like "when is the best time to run the dishwasher" etc. As mentioned in one of the posts here, my power company is also about to move to Off Peak/ ON Peak rates. So my goal is to try to better manage my "time of use" for my big wattage devices.

Also, I am able to get my daily (and hourly) meter reading emailed to me from my power company. So I really don't need a device to track my total house's energy consumption.

I am in the process of adding current sensors to each of my major energy users. I currently have sensors on my water heater, electric baseboard heaters (6 sensors), well pump, gas furnace, and air conditioner. Whenever any one these devices turns ON/OFF, Homeseer captures the event and writes the data to a database. I also have a small vbscript program that searches the Homeseer log at the end of each day and adds information about lights, ceiling fans, electric blanket, etc, usage to the database. This gives me a pretty good picture about how much power I am using and when I am using it.

Hope this gives you some additional ideas.

Steve Q

 

[politics123]

[*]HOME BUILT http://www.btinternet.com/~jon00/electmon.shtml
[/list]I went the HOME BUILT route, with about $20 worth of parts. It actually does read the infra-red pulses from my digital meter, but I haven't done the rest of the work to read the data into a database for time-based graphs.

I'm using CQC and have a 'datalogger' driver which should be able to handle the database stuff and graphing. I really like this idea!

Yes, it's a fun little project. I was originally found the bwired.nl site, but proper credit should be given to jon00. I think I found the velleman kit on qkits for $12. You can test the kit out with a TV remote... make sure the "light" flashes everytime you push a button, and you'll know your detector works fine. This only works with a meter with a IR pulse light. Good luck!

 

[Beamer]

Thank you all for some great ideas and suggestions

nsisman - my board will have some form of serial output protocol where you can get the data in real time from any system and do something with it. Writing PC-based software is something I would likely tackle eventually, but first I want to get the hardware end of things figured out

politics - that welserver stuff is pretty cool! Looks like a nuclear power plant control system

upstate & others - more than just the barebones 2 CT's, that's a good idea (for sub-circuit metering)

BraveSirRobin - I plan on using Current Transformers and A/D converters meant for power metering

lazyone - I definitely need to look into the specifics of the Elk comms

WayneW - not a big fan of pulse either. Short-term logging, a good idea that hadn't come to mind! 232 vs 485... maybe I'll make the comms board a seperate piece. I definitely like the modular idea to keep it cheap and simple for those who want it that way.

SteveQ - your power company emails you? Neat idea!

Today I've been trying to figure out how to do a switchmode power supply to get my 120 to 5V (a lot less board space than a linear PS). Considering some of your suggestions makes me think I should add an EEPROM, a real-time clock, and some sort of battery backup. My poor uC is going to be talking in at least 4 directions at once, poor thing...

That whirring sound you hear is my head... darn you all, now I won't be able to sleep tonight

Brian Rondeau