Just connect the red to wire positive and black wire to negative to power supply the meter and then connect the yellow wire to the power supply source you want to measure, that's it! Great for monitoring voltages during development and debugging or as a permanent part of the project.

Thus, 3-phase system loads are designed to operate at the nominal voltage of 460 V with an overvoltage tolerance of 20 V. Both 460 V and 480 V were 3-phase voltages used for supplying industrial loads. Domestic systems, having lower power supply demands, operate with lower voltage levels.

In a 3-phase system, the line voltage is the potential difference between any 2 lines or phases; it was designated by V Line or V-L-L. If R, Y, and B represent the 3 phases (red, yellow, and blue), then the voltage difference between R and Y, Y and B, and B and R is the line voltage.

In a 3-phase system, there are three conductors, each carrying an alternating current with a phase difference of 120 degrees. This results in a more than efficient and balanced distribution of power supply, allowing for higher voltage levels such as 380 v.

To measure power supply in a three-phase system, it would seem necessary to use 3 wattmeters, each connected to neutral for a common terminal, and each responding to a line-to-neutral voltage and a line current. One would then add up the power supply indicated on each wattmeter.