Using a current transformer

Forum 2005-2010 (read only) Hardware Interfacing
1

I'm looking to use an Arduino and a current transformer (from TED -- The Energy Detective) to do some power measurement around the house.

I just got the current transformers, and I wanted to verify that they work, but having some trouble at it.

Here's what I'm doing:

  • Connected a resistor (tried 1k and 5k ohms) across the two wires coming out of one of the current transformers
  • Clamped the current transformer around the power cord of an electric heater
  • Tried to measure the voltage drop across the resistor with a multi-meter

Since the heater draws 1400w, I'd have expected the multi-meter to give me some reading between 0 and 3v across the resistor connected to the current transformer, yet I'm getting nothing.

What am I doing wrong? The multi-meter is the auto-sensing digital kind, and I have it on the A/C volts measurement setting.

Thanks in advance!

Razvan.

2

That was it, I was clamping the current transformer around both wires. When I clamp it around just one wire it works. Thank you!