2.2.1 Calculate the inductive reactance of the inductor - NSC Electrical Technology Power Systems - Question 2 - 2020 - Paper 1

To find the voltage drop across the capacitor ( V_C), we first determine the capacitive reactance ( X_C):

$X_C = \frac{1}{2\pi f C}$

Where:

• Capacitance ( C) = 150 µF = 150 \times 10^{-6} F

Substituting the values:

$X_C = \frac{1}{2 \times \pi \times 60 \times 150 \times 10^{-6}}$ $X_C \approx 17.68 \Omega$

Voltage drop across the capacitor can then be determined using Ohm's Law: $V_C = I_C \cdot X_C$

Assuming the current ( I_C) through the capacitor is known or can be calculated, substitute this value to find V_C.

The supply voltage is leading because the capacitive reactance is greater than the inductive reactance. In the circuit diagram, V_C and I_C lead the supply voltage V_S. Since I_R and V_R are in phase, this indicates that the circuit is predominantly capacitive, confirming that the voltage is leading.

The phasor diagram should include the following components: 1. I_C (current through the capacitor) leading V_S (supply voltage). 2. V_C (voltage across the capacitor) in line with I_C. 3. I_R (current through the resistor) in phase with V_R (resistor voltage). 4. V_L (voltage across the inductor) lagging I_L (current through the inductor).

Label these components clearly and ensure the magnitudes represent their relationships correctly.