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A 415-V, 50-Hz supply is applied to a three-phase star-connected balanced load. Each [10]phase has an impedance of R+jX ohms, where R=15 n and X = 13.4 n. Find the(i) phase voltage, f'2(ii) phase current,(iii) line current,(iv) power factor,(v) active power,(vi) reactive power,S,vii) total VA

Question

A 415-V, 50-Hz supply is applied to a three-phase star-connected balanced load. Each [10]phase has an impedance of R+jX ohms, where R=15 n and X = 13.4 n. Find the(i) phase voltage, f'2(ii) phase current,(iii) line current,(iv) power factor,(v) active power,(vi) reactive power,S,vii) total VA

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Solution

To solve this problem, we will follow these steps:

Step 1: Calculate the phase voltage (Vph): The phase voltage (Vph) can be calculated using the formula: Vph = Vline / √3 where Vline is the line voltage.

Given that the line voltage (Vline) is 415 V, we can substitute this value into the formula: Vph = 415 / √3 Vph ≈ 239.6 V

So, the phase voltage is approximately 239.6 V.

Step 2: Calculate the phase current (Iph): The phase current (Iph) can be calculated using Ohm's Law: Iph = Vph / Z where Z is the impedance of each phase.

Given that the impedance (Z) is R + jX, where R = 15 Ω and X = 13.4 Ω, we can substitute these values into the formula: Iph = 239.6 / (15 + j13.4) Iph ≈ 10.8 ∠ 41.2° A

So, the phase current is approximately 10.8 ∠ 41.2° A.

Step 3: Calculate the line current (Iline): The line current (Iline) can be calculated using the formula: Iline = √3 * Iph

Substituting the value of Iph into the formula: Iline = √3 * 10.8 Iline ≈ 18.7 A

So, the line current is approximately 18.7 A.

Step 4: Calculate the power factor (PF): The power factor (PF) can be calculated using the formula: PF = cos(θ) where θ is the angle between the voltage and current phasors.

Given that the phase current is 10.8 ∠ 41.2° A, we can calculate the power factor: PF = cos(41.2°) PF ≈ 0.743

So, the power factor is approximately 0.743.

Step 5: Calculate the active power (P): The active power (P) can be calculated using the formula: P = √3 * Vline * Iline * PF

Substituting the given values into the formula: P = √3 * 415 * 18.7 * 0.743 P ≈ 10,000 W

So, the active power is approximately 10,000 W.

Step 6: Calculate the reactive power (Q): The reactive power (Q) can be calculated using the formula: Q = √3 * Vline * Iline * sin(θ)

Substituting the given values into the formula: Q = √3 * 415 * 18.7 * sin(41.2°) Q ≈ 8,700 VAR

So, the reactive power is approximately 8,700 VAR.

Step 7: Calculate the apparent power (S): The apparent power (S) can be calculated using the formula: S = √3 * Vline * Iline

Substituting the given values into the formula: S = √3 * 415 * 18.7 S ≈ 12,900 VA

So, the total apparent power is approximately 12,900 VA.

In summary: (i) The phase voltage is approximately 239.6 V. (ii) The phase current is approximately 10.8 ∠ 41.2° A. (iii) The line current is approximately 18.7 A. (iv) The power factor is approximately 0.743. (v) The active power is approximately 10,000 W. (vi) The reactive power is approximately 8,700 VAR. (vii) The total apparent power is approximately 12,900 VA.

This problem has been solved

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