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Topic: want to use a CT to check for blown bulb (Read 126 times) previous topic - next topic

gpop1

4 bulbs that are being used for a heater (these may be ceramic so they will admit no light)

to test that the bulb heater is working I want to monitor the amps as a simple pass or fail

so lets say that the bulb/heater is 40watt @110v so 0.36 amps

I just want to code something simple like

if output is on ct should read >0.25amps

now the trouble is I can find very little info on this ct

http://www.lctech-inc.com/Hardware/Detail.aspx?id=b7cc0993-f3c6-45ca-9614-9254d336114a

its a basic ct with a burden resistor that has 201 written on it

the web site says that a onboard sampling resistor has been added but they don't say what ohms that is. Is there such a thing as a 201 ohm resistor?

The next problem I presume will be that the ct will try to output ac in relationship to the primary winding.

I have looked at

http://openenergymonitor.org/emon/buildingblocks/ct-sensors-introduction

which gives a good information.  I was just wondering if you guys have any advice as im only looking for a simple amp proven rather than monitoring setup. Im not sure if something as simple as a diode bridge and a capacitor could give me a basic stable dc voltage?




DrAzzy

A resistor marked 201 is a 200 ohm resistor. (20*10^1) - same as the color code /ok
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raschemmel

#2
Dec 10, 2015, 05:35 am Last Edit: Dec 10, 2015, 05:54 am by raschemmel
Quote
now the trouble is I can find very little info on this ct  
Everything you need to know is on that page.
transfer ratio is 1mA/A
5A = 5 mA out from the two little pins on the CT.

What more could you possibly need to know ?

Quote
I was just wondering if you guys have any advice as im only looking for a simple amp proven rather than monitoring setup. Im not sure if something as simple as a diode bridge and a capacitor could give me a basic stable dc voltage?  
How much electronics experience do you have ?

Maybe this would help.

or this

Possibly adding an RC LPF on the output of the rectifier would yield a readable analog voltage.
I would suggest a 4.7k ohm resistor with a 1 uF to 4.7 uF cap.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

gpop1

thanks for the help guys. I did O-level electronics in school over 25 years ago so reading and understanding a basic circuit is not a huge deal. The big difference is that electronics has advanced over the last 25 years and I have not kept up with the changes. I do not own a scope so im going to play with the ct on the bench and go from there. I have some industrial ct's 4-20ma so theres always plan B

raschemmel

#4
Dec 10, 2015, 01:24 pm Last Edit: Dec 10, 2015, 11:11 pm by raschemmel
You  [EDIT] need a block diagram first . Then you can fill in the blocks.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

gpop1

A resistor marked 201 is a 200 ohm resistor. (20*10^1) - same as the color code /ok
yep that makes way more sense now.

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