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### Topic: 20A CT Sensor (Read 14011 times)previous topic - next topic

##### Nov 19, 2012, 01:30 pm
Hello,
I just wanna know if it's possible to build an energy monitor like this one:
http://openenergymonitor.org/emon/buildingblocks/how-to-build-an-arduino-energy-monitor-measuring-current-only

but not using the CT sensor used in that project, i want to use this one (cheaper):
http://store.ecofront.biz/catalog/product_info.php?products_id=35

thanks a lot!

#### johnwasser

#1
##### Nov 19, 2012, 03:01 pm
Just calculate the proper burden resistor using the instructions on this page:

http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface
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#2
##### Nov 22, 2012, 01:21 pm
Thanks a lot!
I tried to calculate the proper burden resistor but i need to know the turns of the CT. How is possible to find it out?

#### johnwasser

#3
##### Nov 22, 2012, 02:56 pm

Thanks a lot!
I tried to calculate the proper burden resistor but i need to know the turns of the CT. How is possible to find it out?

I followed the link that says "For more detailed specifications see the ecofront.com.au".  Once there I followed the link to the page of sensors:  http://www.ecofront.com.au/energy-monitor-sensors.php

That page says 2000 turns.

You could also calculate it if you had the input current and output current.  If the output current at 20A was 10 mA (0.01 A) you would divide 20 by 0.01 to get 2000.
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#4
##### Nov 23, 2012, 03:34 am
Thanks again.
I calculated the burden resistor and the result was 177 Ohms resistance.
- What resistor is better, 174 Ohms or 178 Ohms resistor?
- Is it ok if I use a 10K resistor as a biasing voltage divider (Rvd) as is shown in the tutorial?
- In this schematic (http://openenergymonitor.org/emon/sites/default/files/current.png) there is a capacitor (C1). What's his value?

#### johnwasser

#5
##### Nov 23, 2012, 02:41 pm

Thanks again.
I calculated the burden resistor and the result was 177 Ohms resistance.
- What resistor is better, 174 Ohms or 178 Ohms resistor?
- Is it ok if I use a 10K resistor as a biasing voltage divider (Rvd) as is shown in the tutorial?
- In this schematic (http://openenergymonitor.org/emon/sites/default/files/current.png) there is a capacitor (C1). What's his value?

I'd use the lower resistor to keep the voltage from going over 5V.

The first article you pointed to says:

"Current sensing electronics
1x CT sensor yhdc SCT-013-000
1x Burden resistor 18 Ohms if supply voltage is 3.3V or 33 Ohms if supply voltage is 5V.
2x 10kOhm resistors (or any equall valued resistor pair upto 470kOhm)
1x 10uF capacitor"

So I think 10K is a good choice for RDV and 10 uF for the capacitor.
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#### joie

#6
##### Feb 25, 2013, 03:52 pm
hello!

I was wondering if this project would also work for an DC voltage?
I'm thinking of making one myself and i'm new in arduino and Ct sensors.
i'm planning to use this one http://www.pdfdoc.ru/process-control/sensors-and-transducers/current-transducers/current-transformers/as-100-current-transformer-15a-20-200khz-as-100-400-8575.

thank you.

#### retrolefty

#7
##### Feb 25, 2013, 04:18 pm

hello!

I was wondering if this project would also work for an DC voltage?
I'm thinking of making one myself and i'm new in arduino and Ct sensors.
i'm planning to use this one http://www.pdfdoc.ru/process-control/sensors-and-transducers/current-transducers/current-transformers/as-100-current-transformer-15a-20-200khz-as-100-400-8575.