The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures

Wattmeter reading = VPC ICC cos (VPC ^ ICC)

A current coil of wattmeter is connected to the CT of R-phase. So, wattmeter takes the current flowing through the R phase.

Pressure coil is connected across the Y phase and B phase. So, wattmeter takes the voltage VYB

Now, the wattmeter reading is,

W = VYB IR cos (VYB ^ IR)

Let the load angle is ?, the angle between VYB and IR is (90 – ?)

⇒ W = VYB IR sin ? = reactive power of the R phase.

please explain the answer if known to anyone.