ABSTRACT
In the two branch parallel circuit containing resistance R and inductance L shown in Figure 16.1, the current flowing in the resistance, IR, is in-phase with the supply voltage V and the current flowing in the inductance, IL, lags the supply voltage by 90°. The supply current I is the phasor sum of
R IL), shown as angle in the phasor diagram. From the phasor diagram:
I D √ I2R C I2L, (by Pythagoras’ theorem)
where IR D V R
and IL D V XL
tan D IL IR , sin D IL
I and cos D IR
I (by trigonometric ratios
Circuit impedance, Z D V I
Problem 1. A 20 resistor is connected in parallel with an inductance of 2.387 mH across a 60 V, 1 kHz supply. Calculate (a) the current in each branch, (b) the supply current, (c) the circuit phase angle, (d) the circuit impedance, and (e) the power consumed.
