New Brultech Energy Monitoring Model (ECM-1240) due in 2009
- Thread starter sic0048
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beelzerob
Senior Member
Just talked to Paul, and the FCC testing is completed and passed, but they've just had one distraction/problem after another, not related to the 1240, but more like employee and equipment. So that's why the delay and the long hours for them. They're hoping for a Friday release, but it may turn into Monday because then they'll have the weekend to finally square everything up.
So......soooooon.
So......soooooon.
WayneW
Senior Member
I believe/assume/guess that "net metering" means it is direction sensitive, so that it could detect buying versus selling.
hucker
Active Member
Current meters do have a direction associated with them...for those of you that remember the right hand rule from freshman physics. If you dig through the brultech site you'll see references to the use in systems with solar. I suspect that the 1240 system would work best for this purpose since it has extra channels...
Had to look up right hand rule (slept a lot in physics).
Hope it does work that way so I can keep tabs on local power company and what they say I am selling back (seems like not much for the amount of production I have)
It had best do net metering well, I'll be feeding it two (actually 3, but two small ones are paralled) grid-tied inverters into the system. I think all I'll have to do is run both "hots" from the inverters thru one current transformer. If I've got this wrong, somebody let me know...
I think (on a good day...:blink
that the way to sense which "direction" the AC current is flowing is that since the inverters synchronize to the incoming AC waveform, that you could see a timing difference in the incoming and outgoing currents/voltages. Thats my best SWAG...It works the same as how they do power factor: the Brultech has to simultaneously sense current (which has an implied "direction") and instantenous voltage (where on the sine wave the voltage is).
Multiplying those together gives you instantaneous power, which could be negative in the event of a net outflow to the grid.
Multiplying those together gives you instantaneous power, which could be negative in the event of a net outflow to the grid.
I believe it is simpler than that, current transformers have a polarity, that is if current if flowing one direction the output may either be high or low relative to the high or low of the measured current a/c waveform. The Brultech measures voltage through its own power transformer which it can use as a reference to know if the measured line current is high or low, if current if flowing "in" then when line current is high, the ct output will be high, if current if flowing "out" then when the line current is high the ct will be low instead.
I'm not sure if there is a way to derive direction without the second voltage measurement that conveniently the Brultech has is there?
Justin
I'm not sure if there is a way to derive direction without the second voltage measurement that conveniently the Brultech has is there?
Justin
It had best do net metering well, I'll be feeding it two (actually 3, but two small ones are paralled) grid-tied inverters into the system. I think all I'll have to do is run both "hots" from the inverters thru one current transformer. If I've got this wrong, somebody let me know...
I think (on a good day...:blink
It may be simpler than I thought at first without the need for reference voltage, after digging around, they probably use a "centered" hall effect sensor to measure current on the CT output, the centered sensors will put out say 0-5vdc with 2.5v being no current, anything above 2.5v is one direction, below 2.5v the other, then its just a matter of the CT being put on the right direction and the Brultech knowing the polarity of the CT's (additive or subtractive) and getting the leads right from the ct to the Brultech X1, X2.
Alternating current alternates, so even when drawing power from the electric company, half the time (1/120th of a second at a time) the current is flowing one direction, and the other half, it's flowing the other direction. Knowing the average current flow without a concurrent voltage measurement won't tell you anything entirely useful.
I don't see any way around them needing a reference voltage source (even just for power factor correction), and in fact, they do have a reference voltage source in the system and claim to do power factor accounting.
I don't see any way around them needing a reference voltage source (even just for power factor correction), and in fact, they do have a reference voltage source in the system and claim to do power factor accounting.
I guess the bottom line is...if it works well and shows up in the Online Store fairly soon, I'll be a happy camper :blink:
Only semi follow a lot of this. My thought was to put 2 CT's on mains, facing opposite direction..one measures flow one way, the second measures flow the other way. This now seems to simplistic from what the capabilities of the monitor seem to be
BTW, i am new here and the info is good. Is there anything out there comparable to this (I know TED has been promising something like this, but does not seem it is going to happen)
BTW, i am new here and the info is good. Is there anything out there comparable to this (I know TED has been promising something like this, but does not seem it is going to happen)
