In two wattmeter method, we have two types of connections:

- Star connection of loads
- Delta connection of loads.

In **star connection** of load, the reading of wattmeter one is product phase current and voltage difference (V2-V3) and the reading of wattmeter two is the product of phase current and the voltage difference (V2-V3). Thus, the total power of the circuit is sum of the reading of both the wattmeters.

Mathematically we can write *P=P1+P2=I1(V1+V2) + I2(V2-V3)*.

But *I1+I2+I3=0*, hence putting the value of *I1+I2=-I3*.

We get total power as ** P=V1I1+V2I2+V3I3**.

In

**delta connection**of loads, the loads are connected as

**:**

The reading of wattmeter one can be written as

*P1 = -V3(I1 – I3)*and reading of wattmeter two is

*P2= -V2(I2 – I1)*.

But V1+V2+V3=0, hence expression for total power is

**.**

*P=V1I1+V2I2+V3I3*## Practical on Two Wattmeter method

## Watch this Video to know about 2 Wattmeter method

Also Check Out – Working of Single Phase Energy Meter

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