Math Problem Statement

Un motor M es conectado a una red de distribución monofásica alterna. A fin de determinar su funcionamiento, se le conecta un amperímetro, voltímetro, y vatímetro. Si estos instrumentos tienen las lecturas indicadas en la figura, determinar: a) El cosφ y los VAr consumidos por el motor. b) Impedancia en módulo y fase. c) Resistencia R y reactancia inductiva del circuito X_L equivalente del motor, asumiendo conexión serie entre ambos.

Solution

To solve this problem, we can go through the required steps based on the information provided:

Given Data:

  • Voltage V=230VV = 230 \, \text{V}
  • Current I=12AI = 12 \, \text{A}
  • Power P=2208WP = 2208 \, \text{W}

Calculations:

  1. Power Factor (cosφ\cos \varphi):

    • The power factor cosφ\cos \varphi can be calculated using the formula: cosφ=PVI\cos \varphi = \frac{P}{V \cdot I}
    • Substituting the values: cosφ=2208230×120.8\cos \varphi = \frac{2208}{230 \times 12} \approx 0.8
  2. Reactive Power (VAr):

    • The reactive power QQ (in VAr) can be calculated using: Q=VIsinφQ = V \cdot I \cdot \sin \varphi
    • First, calculate sinφ\sin \varphi using cosφ\cos \varphi: sinφ=1(cosφ)2=10.820.6\sin \varphi = \sqrt{1 - (\cos \varphi)^2} = \sqrt{1 - 0.8^2} \approx 0.6
    • Then, calculate QQ: Q=230×12×0.61656VAr(1.65kVAr)Q = 230 \times 12 \times 0.6 \approx 1656 \, \text{VAr} \, (\approx 1.65 \, \text{kVAr})
  3. Impedance ZZ (magnitude and phase):

    • The impedance ZZ magnitude is given by: Z=VI=2301219.17ΩZ = \frac{V}{I} = \frac{230}{12} \approx 19.17 \, \Omega
    • The phase angle θ\theta is the arccosine of the power factor: θ=cos1(0.8)36.87\theta = \cos^{-1}(0.8) \approx 36.87^\circ
  4. Resistance RR and Inductive Reactance XLX_L:

    • The resistance RR is calculated as: R=Zcosθ=19.17×0.815.3ΩR = Z \cdot \cos \theta = 19.17 \times 0.8 \approx 15.3 \, \Omega
    • The inductive reactance XLX_L is: XL=Zsinθ=19.17×0.611.5ΩX_L = Z \cdot \sin \theta = 19.17 \times 0.6 \approx 11.5 \, \Omega

Summary of Results:

  • a) Power Factor (cosφ\cos \varphi): 0.80.8
  • a) Reactive Power (VAr): 1.65kVAr1.65 \, \text{kVAr}
  • b) Impedance ZZ: 19.17Ω19.17 \, \Omega at 36.8736.87^\circ
  • c) Resistance RR: 15.3Ω15.3 \, \Omega
  • c) Inductive Reactance XLX_L: 11.5Ω11.5 \, \Omega

Would you like to delve further into any part of this solution, or have any other questions?

Follow-up Questions:

  1. How would changes in the current affect the reactive power?
  2. What is the significance of a power factor of 0.8 in practical scenarios?
  3. How does inductive reactance XLX_L affect the overall circuit behavior?
  4. Why is the impedance phase angle relevant in AC circuits?
  5. How could this analysis change if the motor was connected to a different voltage?

Tip:

In AC circuits, always remember that reactive power (measured in VAr) doesn't contribute to the actual work done but impacts the phase angle and overall power efficiency.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Electric Power
AC Circuit Analysis
Impedance
Power Factor
Reactive Power

Formulas

Power Factor (cos φ) = P / (V × I)
Reactive Power (Q) = V × I × sin φ
Impedance (Z) = V / I
Resistance (R) = Z × cos θ
Inductive Reactance (X_L) = Z × sin θ

Theorems

Trigonometric identities in power calculations
Ohm's Law

Suitable Grade Level

College-level Electrical Engineering