Re: [volt-nuts] current-nut question .. total waste of ones time type question
I agree with John on this one - put in another meter socket downstream if you really want to experiment, and be sure to have a main disconnect besides the utility's meter. If you are changing the service entrance, you will likely have issues with the local permits for it, and with the utility company - they don't like to see anything unusual or confusing. A couple of years ago I put in a new service at our vacation house, that had an ancient mish-mosh of crap that was ready to catch on fire, stuffed into too small a panel, and with no main disconnect except by pulling the utility meter outside. I collected a nice new meter box/load center and other needed parts, assuming I could just have PGE pull the meter outside, replace the old load center with the new, and have my own meter and disconnect inside. When I applied for the permit from the county, this caused nothing but grief and confusion - they didn't understand, and neither did PGE, why anyone would want a second meter. They get suspicious I think, because they don't want multiple residences set up on single-residence zoning, so another meter is a red flag, even though I explained many times that it was just in series, for monitoring and alternative energy experiments such as grid-tie stuff to come later. Furthermore, I had to make it meet all current codes, which meant I needed to have a separate disconnect on the outside, and updated grounding. Ultimately, I ended up replacing the whole works with my new meter/load center on the outside, with PGE's meter installed, and another new meterless load center on the inside. It all worked out OK, but it became a week-long project involving a big hole in the wall and reframing, instead of a one day quick-changeout as I had planned. I can now change it and add meters and CTs and whatever, downstream, but I kind of lost interest after going through all that. The novelty wears off quickly when you have to first get all the basic stuff properly working. Also, whatever you add should be done in ways that are safe common sense-wise, and meet electrical codes. A mistake in fooling with a typical 200A 240V main may cause much more than a spark and a pop. Ed ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] current-nut question .. total waste of ones time type question
Next spring I'm going be rewiring my house. And for 'fun' I want to drop a couple current sensors on the input side of the main panel. Being a beginner 'nut', I'm looking for more accuracy then needed. Voltage, Frequency, waveform will be taken care of later, but accurate current has be a bit flustered. I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils. And the many new IC's on the market that take care of a lot of things. Has someone done this before ? And if so any experiences to share ? -pete ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] current-nut question .. total waste of ones time type question
There was a Circuit Cellar article on this many moons ago. Basically, it was: Take a torroid ferrite core, wrap ~20 turns of #20 through it, pass the wire you want to sense current in through the core, and hook the output of the coil to an op amp. Look at output of op amp with a/d converter. Do some math. :) I have a few on individual circuits in my electrical panel (sump pump, furnace, etc). I dipped the coil assembly in plasti-dip to insulate them. Have not looked at it in a long while though. The control processor croaked and I've never bothered to fix it. Bob On Apr 29, 2014, at 13:25, Pete Lancashire p...@petelancashire.com wrote: Next spring I'm going be rewiring my house. And for 'fun' I want to drop a couple current sensors on the input side of the main panel. Being a beginner 'nut', I'm looking for more accuracy then needed. Voltage, Frequency, waveform will be taken care of later, but accurate current has be a bit flustered. I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils. And the many new IC's on the market that take care of a lot of things. Has someone done this before ? And if so any experiences to share ? -pete ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] current-nut question .. total waste of ones time type question
Years ago I installed a TED-1000 (now obsolete) system from http://www.theenergydetective.com/. Their software is terrible but the system works. This system uses two current transformers and a single voltage measurement system that all go inside your circuit breaker box. I don't recall the sampling rate (1 KHz maybe). The instantaneous voltage and current measurements are multiplied, summed, and transmitted once per second. The data is transmitted to a receiver using the house wiring (similar to X-10). People have hacked the system to use their own receiver. I haven't directly measured accuracy; monthly totals are usually about 5% low when compared to my electric bill. The software compensates for missing readings. Resolution seems to be around 10 watts. Brent On 4/29/2014 11:25 AM, Pete Lancashire wrote: Next spring I'm going be rewiring my house. And for 'fun' I want to drop a couple current sensors on the input side of the main panel. Being a beginner 'nut', I'm looking for more accuracy then needed. Voltage, Frequency, waveform will be taken care of later, but accurate current has be a bit flustered. I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils. And the many new IC's on the market that take care of a lot of things. Has someone done this before ? And if so any experiences to share ? -pete ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] current-nut question .. total waste of ones time type question
Getting 2 % is pretty easy, many commercial CT's at 0.3% at the transformer, resistance of the wire from the CT to the load (burden in the electrical world), and all the things that effect voltage measurements come into play. A well designed setup can get to 0.5%. Thanks to surplus a classic 5A CT can be found for a few $'s. More modern instrument grade CTs are expensive unless you can grab one off the usual auction places. A classic 100A or 200A:5A is a good 4-5 square and can be as much as 2-3 thick. Today you don't need the 5 Amps, heck 10-50 mA is good enough, so the size can be smaller. I've been trying to shoot for say 0.1% to 0.2%. Again for 'fun'. Where some more fun comes in is when you get below 10%, that would be 10Amps using a 100A CT. The industry specs stop at 10%. A 0.3% transformer is only 0.3% at full rating (and above). Was just looking to see if anyone has come up with something new / low cost / etc. On Tue, Apr 29, 2014 at 12:06 PM, Brent Gordon volt-n...@adobe-labs.comwrote: Years ago I installed a TED-1000 (now obsolete) system from http://www. theenergydetective.com/. Their software is terrible but the system works. This system uses two current transformers and a single voltage measurement system that all go inside your circuit breaker box. I don't recall the sampling rate (1 KHz maybe). The instantaneous voltage and current measurements are multiplied, summed, and transmitted once per second. The data is transmitted to a receiver using the house wiring (similar to X-10). People have hacked the system to use their own receiver. I haven't directly measured accuracy; monthly totals are usually about 5% low when compared to my electric bill. The software compensates for missing readings. Resolution seems to be around 10 watts. Brent On 4/29/2014 11:25 AM, Pete Lancashire wrote: Next spring I'm going be rewiring my house. And for 'fun' I want to drop a couple current sensors on the input side of the main panel. Being a beginner 'nut', I'm looking for more accuracy then needed. Voltage, Frequency, waveform will be taken care of later, but accurate current has be a bit flustered. I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils. And the many new IC's on the market that take care of a lot of things. Has someone done this before ? And if so any experiences to share ? -pete ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
