Question 39E2

Inductive (choke) input filters are designed to smooth the current flowing from the rectifier. An inductor resists changes in current, so it draws current over a longer portion of the AC cycle rather than in sharp pulses. Here's why option D is correct: * **Good voltage regulation:** Because the inductor smooths the current, it helps maintain a more constant output voltage despite changes in load current. When the load demands more current, the inductor releases stored energy, preventing a significant voltage drop. * **High transformer utilization factor:** By drawing current for a longer duration and with lower peak values, the transformer's windings are used more efficiently, resulting in a higher utilization factor. * **Low rectifier peak currents:** The smoothed current flow means the rectifier diodes do not have to conduct very high, short-duration peak currents to charge a capacitor. This reduces stress on the rectifiers and transformer. Conversely, capacitor-input filters provide a higher output voltage (closer to the peak AC voltage) but suffer from poor voltage regulation, very high rectifier peak currents (as the capacitor rapidly recharges), and a lower transformer utilization factor.