Will the two-wattmeter method work for all three-phase loads eg unbalanced loads inductive loads capacitive loads and delta-connected loads?

Answer 1

Blondel's Theorem tells us that, to measure the total power of a three-phase load (balanced or unbalanced), we can use one less wattmeter than there are conductors supplying that load.

So the two-wattmeter method will work for anythree-phase load, provided there are only threeconductors supplying that load, e.g. three-wire delta or three-wire star (wye).

Bear in mind that wattmeter's read true power (expressed in watts) and ignores the reactive power of inductors and capacitors.