Two wattmeter connected to measure the power in a 3 phase balanced delta connected load read w1 = 12kw and w2=15kw respectively . if the same load is connected in star , then the wattmeter would read?

Question

Answer

Answer

Given

W1 = 12 kW

W2 = 15 kW

To Find

Power reading of the load when it is connected in star

Solution

When a balanced delta connected load is connected in star, the phase current becomes 1/sqrt(3) times the line current. Similarly, the phase voltage becomes sqrt(3) times the line voltage. Therefore, the power in the load also changes as follows:

Line power = 3 x Phase power (for a balanced load)

Phase current = Line current / sqrt(3)

Phase voltage = Line voltage x sqrt(3)

Using the above equations, we can find the power in the load when it is connected in star as follows:

Line power = W1 + W2 = 12 kW + 15 kW = 27 kW

Phase power = Line power / 3 = 27 kW / 3 = 9 kW

Answer

The wattmeter reading of the load when it is connected in star is 9 kW.

Answer

W1=4kw,w2=5kw

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