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Items needed to monitor status of house power sources

Posted: Sat Apr 06, 2013 8:33 pm
by BobS0327
I need to monitor my home's commercial power and the power from my automatic standby generator. I really don't need anything fancy just non invasive current sensors for both the mains and the backup generator. The output from both of these current sensors would be feed into an analog input device which would be connected to my computer. All I want to know is when the mains is off/on and when the automatic standby generator is off/on.

I've checked out the 3503_0 - i-Snail-VC-100 Current Sensor 100Amp current sensors. But it appears that this sensor is an invasive sensor. In other words, I would have to get a professional electrician to install the sensor on the mains. Also, I'm not sure that my mains wire would fit thru the sensors. I have a 200 AMP U.S. service entrance.

Thus, I would need advice as what Phidgets items I would need to make my non invasive project a reality keeping in mind that I only need to know the on/off status of both power sources. I do not need to measure current usage etc.

Re: Items needed to monitor status of house power sources

Posted: Sun Apr 07, 2013 2:29 pm
by frodegill
I love Phidgets, but when I bought a house and needed to get a clear view of power usage I got myself a CurrentCost EnviR. With a few lines of C code, I had logging available in Munin (just as my Phidgets log light, temperature and humidity). The EnviR has its drawbacks (only a transmitter, so no way to detect transmission collisions and dropped readings), but it is a very elegant sollution. Outputs watts as XML every 6 seconds.
You can probably get the job done using Phidgets, but at least for me, the CurrentCost wireless IAMs makes that setup incredible simple.

Re: Items needed to monitor status of house power sources

Posted: Mon Apr 08, 2013 10:21 am
by Patrick
Since you have 200 Amp service, you really need a 200 Amp sensor to be safe, which we don't sell. Also, you probably want a split core current sensor, so you don't have to detach your power lines to install it. If you are interested in a more finished solution, see http://www.theenergydetective.com

Looking at your requirements - you may not want a current sensor at all. You may want an AC voltage sensor like 3508 - this will definitely tell you whether your mains power is on or off.

-Patrick

Re: Items needed to monitor status of house power sources

Posted: Tue Apr 09, 2013 7:32 am
by BobS0327
TED and EnviR both appear to be fascinating applications. But the requirements of my project is to just check for the existence or nonexistence of commercial power/backup power. It's primarily a home security application which will send a text message to a user if there are any power issues. Tracking energy consumption would be out of the scope of the application.

But I do need a non invasive solution since this application is also being developed for a small group of users, who in my opinion, do not have the experience to work directly with high voltage.

I was hoping for a very basic open ended Current Transformer (CT) that could be connected to a computer interface to provide the on/off status of the power source.

Thanx for the input.

Re: Items needed to monitor status of house power sources

Posted: Tue Apr 09, 2013 9:24 am
by Patrick
Why not use a simple 5 V output power supply, just plugged into an outlet. You could wire this directly into an input on a 1018 or 1011 to monitor whether the power is cut. Of course, the computer will need to be on backup power. This would be the cheapest/simplest/safest solution in my opinion.

-Patrick

Re: Items needed to monitor status of house power sources

Posted: Tue Apr 09, 2013 8:03 pm
by BobS0327
That would definitely solve half the problem by monitoring the commercial power source. Unfortunately, it doesn't address the other half.. monitoring the standby generator power.

The backup generator is required to "exercise" once a week for 12 minutes to recharge the automotive battery needed to initially start it and also keep the oil circulated in the engine. When it "exercises" it provides power up to the automatic transfer switch and no further. It is at this point that I must monitor the backup power for two reasons (1) ensure that the generator is "exercising" every week (2) verify that it is providing power to the house when the commercial power is not available.

I do realize that your solution will take care of item #2. But I still have to address item #1. In other words, if I didn't have to verify that the backup generator was "exercising" every week, your solution would definitely work.

Just some background info on the backup generator...
The Generac automatic standby generator will start providing power to the house when it senses an absence of commercial power longer than 30 seconds. When this occurs, the automatic transfer switch (ATS) of the backup generator will disconnect the commercial power from the house and feed the generator power into the house. When the generator ATS senses that the commercial power has been restored, it will just reverse the process.

Re: Items needed to monitor status of house power sources

Posted: Wed Apr 10, 2013 9:05 am
by Patrick
So, you want to know when your backup generator is running - but not necessarily providing power to your house? In this case, a current sensor will not help you, because there is no load - no current flowing. The only way is to measure the voltage. I guess another solution would be to attach a vibration sensor to the generator, or use a sound sensor.

-Patrick

Re: Items needed to monitor status of house power sources

Posted: Wed Apr 10, 2013 9:44 am
by BobS0327
The backup generator does provide power up to the Automatic Transfer Switch (ATS) and no further when it is exercising. This ATS is located next to the service entrance (main panel). One easy but invasive method to monitor the backup power at the ATS enclosure would be to use a 250 VAC coil/relay similar to http://www.amazon.com/gp/product/B005T5KT7U/ref=oh_details_o03_s01_i00?ie=UTF8&psc=1 this one since there will always be power in the ATS enclosure whenever the generator is running (exercising or providing power to the house). But installing the device can be potentially dangerous for the inexperienced.