Question 39E5

Power supplies with inductive input filters (also known as choke-input filters) place an inductor in series with the rectifier output *before* the main filter capacitor. This inductor's property of opposing changes in current causes it to smooth the rectified current, spreading out the current draw over a longer portion of the AC cycle. This leads to: 1. **Good Voltage Regulation:** The smoother, more continuous current draw from the rectifier helps maintain the output voltage more consistently under varying load conditions. The output voltage drops less when a load is applied compared to a capacitor-input filter. 2. **High Transformer Utilization Factor:** Because the rectifier currents are lower in peak value and more continuous, the transformer is utilized more efficiently. Its VA (volt-ampere) rating is better matched to the DC power delivered, allowing for a higher percentage of the transformer's capacity to be used effectively. This means the transformer runs cooler and can deliver more DC power for its size. Therefore, options A and D are incorrect because they mention high peak rectifier currents, which are characteristic of capacitor-input filters, not inductive input filters. Option C is incorrect because inductive input filters provide a *high* transformer utilization factor.