TL;DR The two wattmeter method is a practical, mathematically proven technique for measuring total power in a 3-phase, 3-wire system using only two instruments. This blog explains the science behind it, how Blondel's Theorem justifies it, how wattmeter readings are interpreted, and why it remains the go-to method in industrial electrical engineering.
For electrical engineering...
Deutsch 
English
Arabic
French
Spanish
Portuguese
Turkish
Dutch
Italiano
Russian
Romaian
Portuguese (Brazil)
Greek