# Measure current of multiple loads with one sensor?

I have been doing some research for my project which requires to measure power consumption of 8 different loads. For that I plan to measure current in each line and multiply that with the voltage of single phase (220v).

I've been searching and have not been able to find a cheap current sensor. Sensors like ACS712 are available but for about $3 for one which means$24 for 8. That's way to expensive for my project.

So I was wondering, is there a way to use one current sensor, such as ACS712, to measure current in 8 loads (working on the same phase).

I am using arduino for the project.

Thank you.

• No there isn't. – Transistor Jan 20 '16 at 21:51

## 1 Answer

If you're loads are anything other than resistors (e.g. incandescent lamps), or modern electronic devices (laptop charger, new TV, anything with good power factor), then the current measurement alone (times voltage) probably won't give a good measure of the power consumed because of power factor (phase lag between voltage and currents), or distortion.

Can you run all loads concurrently through the sensor, and enable/disable each one in turn ?

• yes i am using triacs to switch the devices on or off individually. – Ujjwal Syal Jan 21 '16 at 10:24
• Then put your single current sensor on the supply line to the triac stack. – R Drast Jan 21 '16 at 15:10
• but that would give total power consumption of the 8 loads. I wish to calculate individual power consumption of the eight loads.. – Ujjwal Syal Jan 21 '16 at 16:00
• Turn off all the Triacs except one. Measure it's current. Turn it off, turn the next one on, measure, etc. Be warned, I have used the ACS712 in the past and you can not take one reading and determine the current. The ACS output has a sine wave, so you have to measure the high peak, and the low valley and add them together to represent the current. – Jeff Jan 22 '16 at 14:24