T
theCase
- Jan 1, 1970
- 0
I've got a tentative plan to try and log power usage in my home, here's
a summary of the plan:
1) Buy two current transformers like these:
http://www.crmagnetics.com/newprod/ProductView.asp?ProdName=CR3110
2) Place one on each "hot" leg of the 240 volts coming into the house,
leaving the ground alone.
3) Place an appropriately sized burden resistor in parallel with each
transformer (this would be done prior to placing the transformers in
place as I understand the possibility of developing high voltages if I
ever have an "open" across the transformer).
4) Sense the voltage using a cheap A/D converter like this;
http://www.dataq.com/194.htm
5) Write some VBA code inside Excel for the conversion of the voltage
to power, data analysis, and logging.
My questions are:
a) Do I need an external amplifier / power supply for any of this, or
would the voltage developed be sufficient to sense through the
transformers directly?
b) Would I need a capacitor/diode across the transformer to rectify the
AC and provide an "average" voltage as opposed to the 60Hz ripple? If
so, any guesses appreciated as to the size needed. I'm thinking the
sampling rate may be around 50/sec.
c) Could I expect reasonable results without getting into lead/lag
power factors and all that crazy math stuff? This is just for an
ordinary home circuit; I'm not running welders or 60 hp pumps.
d) Does George Bush have a clue about what to do in Irag? (Just kidding
on this one, I already know the answer)
This is just a fun for-my-own-benefit type of project. One of those
where the hacking/ doing is more fun than the end results. I also know
enough about electricity/basic electronics to have a healthy respect
for working with the voltages involved and understand that messing
around in the breaker box can be dangerous. And finally I plan on
doing the calibration/testing outside the breaker box using maybe a
toaster to help calibrate it.
a summary of the plan:
1) Buy two current transformers like these:
http://www.crmagnetics.com/newprod/ProductView.asp?ProdName=CR3110
2) Place one on each "hot" leg of the 240 volts coming into the house,
leaving the ground alone.
3) Place an appropriately sized burden resistor in parallel with each
transformer (this would be done prior to placing the transformers in
place as I understand the possibility of developing high voltages if I
ever have an "open" across the transformer).
4) Sense the voltage using a cheap A/D converter like this;
http://www.dataq.com/194.htm
5) Write some VBA code inside Excel for the conversion of the voltage
to power, data analysis, and logging.
My questions are:
a) Do I need an external amplifier / power supply for any of this, or
would the voltage developed be sufficient to sense through the
transformers directly?
b) Would I need a capacitor/diode across the transformer to rectify the
AC and provide an "average" voltage as opposed to the 60Hz ripple? If
so, any guesses appreciated as to the size needed. I'm thinking the
sampling rate may be around 50/sec.
c) Could I expect reasonable results without getting into lead/lag
power factors and all that crazy math stuff? This is just for an
ordinary home circuit; I'm not running welders or 60 hp pumps.
d) Does George Bush have a clue about what to do in Irag? (Just kidding
on this one, I already know the answer)
This is just a fun for-my-own-benefit type of project. One of those
where the hacking/ doing is more fun than the end results. I also know
enough about electricity/basic electronics to have a healthy respect
for working with the voltages involved and understand that messing
around in the breaker box can be dangerous. And finally I plan on
doing the calibration/testing outside the breaker box using maybe a
toaster to help calibrate it.
