Three phase AC power (part of my project)

Thread Starter


Joined Aug 29, 2007
\(\varpi\)Hi all,

I understand that the power supplied by this three phase AC will be constant (since P ~ V^2).

However, how about the voltage and current? The summation will be 0?

Actually, I have a project to measure the current in RSW (Resitance Spot Welding Machine) whic is using three phase AC power. I am required to use the principle of electromagnetic to do the project.

Therefore, I put a steel ring attached with strain gage surround the wire carrying the current. The strain gauge will detect the deflection of the ring caused by electromagnetic force.

After the calculation, I found out that the strain is proportional to current square. Therefore in my case, the strain ~ (I sin (wt))^2. Is that still correct for three phase AC current? Since in my calculation I use single phase AC (I = I sin (wt))

The strain then will be converted to Voltage by using Wheatstone bridge.