Comments on: How much!? http://narwar.net/2008/08/27/how-much/ narwar.net Thu, 29 Jul 2010 19:35:34 +0000 http://wordpress.org/?v=2.1 By: Gerard Gallagher http://narwar.net/2008/08/27/how-much/#comment-1135 Gerard Gallagher Tue, 07 Oct 2008 00:13:56 +0000 http://narwar.net/2008/08/27/how-much/#comment-1135 Hi, Read with great interest your post on the mains monitoring project. I am in the process of building a similar device, and as it happens I also have an owl CT, two of which I bought. I actually took the time to open one and count the turns, which amounted to 3200, and removed the burden resistor. However, I’m having great difficulty in getting a proper ac-dc conversion process running. I live in the Rep. Of Ireland and similar to the UK, we are running 230V AC. I have a 12KVA supply, so therefore I can have a maximum current of 52amps, and I was trying to design the device to therefore give a DC output proportional to 0-50A, with a voltage output of 0-5V DC suitable for a ‘877 ADC. Using a bridge rectifier seems not an option, as the DC voltage produced does not seem to correspond to the ampere reading I am also taking off the live wire with a clamp meter. I’m guessing this is too also due to the voltage drop across the diodes. I’m wondering if you have any schematic or other info on how your project is progressing, as I’d be greatly interested in seeing any ideas on how to solve my current impasse, and considering your schematic is for similar voltages, and using a similar CT, our schematics should be roughly the same. Thanks for your time, and nice blog. Regards, Gerard Gallagher Hi,

Read with great interest your post on the mains monitoring project.
I am in the process of building a similar device, and as it happens I also have an owl CT, two of which I bought. I actually took the time to open one and count the turns, which amounted to 3200, and removed the burden resistor.
However, I’m having great difficulty in getting a proper ac-dc conversion process running. I live in the Rep. Of Ireland and similar to the UK, we are running 230V AC. I have a 12KVA supply, so therefore I can have a maximum current of 52amps, and I was trying to design the device to therefore give a DC output proportional to 0-50A, with a voltage output of 0-5V DC suitable for a ‘877 ADC. Using a bridge rectifier seems not an option, as the DC voltage produced does not seem to correspond to the ampere reading I am also taking off the live wire with a clamp meter. I’m guessing this is too also due to the voltage drop across the diodes.
I’m wondering if you have any schematic or other info on how your project is progressing, as I’d be greatly interested in seeing any ideas on how to solve my current impasse, and considering your schematic is for similar voltages, and using a similar CT, our schematics should be roughly the same.
Thanks for your time, and nice blog.

Regards,
Gerard Gallagher

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