### Beier Electric FP-10 Currrent Sensor

Hi,

I have used a Beier Electric FP-10 Current sensor with Primary current 30A and secondary 0.333V to read the IRMS using the EmonLib and the setup provided for using CT Sensors - Interfacing with an Arduino. I have worked out the although I am unsure of the number of turns on the coil. I have worked the burden resistor and also did some calculations and found out that my Primary Peak Current is 42.426A, my Secondary peak Current is 0.07071 and my SPC is 33.35 ohms. therefore i have set emon1.current(1, 60);. i don't get any real results just some fuzzy numbers... how can i connect this sensor and interface it with my Arduino Uno  and get my desired results??? Right now i am using the schematic and code provided by http://openenergymonitor.org/emon/node/54

### Re: Beier Electric FP-10 Currrent Sensor

Because the  CT output is defined as a voltage, it means that it has a built-in burden resistor. You can find how to calculate the calibration coefficient on the Building Blocks page about calibration theory - the part about voltage output CTs is at the end of the CT section.

However, as your CT output is only 0.33 V rms, and I presume you are using an Arduino with a 5 V supply and 5 V analogue input range, you are only using less than 20% of the available input. That means when you measure current below approximately 1.5 A, accuracy will degrade significantly.

You could amplify the CT output to bring it up to the amplitude that the analogue input expects (which of course would mean that the calibration constant changes to compensate).

### Re: Beier Electric FP-10 Currrent Sensor

Thank you for your response Robert,
is the setup provided in this link still the same for my FP-10 CT? http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface But without the burden resistor? Also how can i amplify the ampliture of the analog input? Because the calibration steps are more than one section in this link: http://openenergymonitor.org/emon/buildingblocks/ct-and-ac-power-adaptor-installation-and-calibration-theory
T