Question 4

The Correct Answer is A **Why option A ("an inductive-resistive load") is correct:** To determine the type of load, we must analyze the key measurements displayed on the digital power meter (as represented by figure "D" in Illustration EL-0256, which is assumed to show specific values): 1. **Power Factor (PF):** The power factor is typically displayed as a value less than 1 (indicating a reactive component) and is often accompanied by a directional indicator (e.g., "LAG" or a negative sign for lagging loads) if the meter is comprehensive. A power factor less than $1$ means the load is not purely resistive. 2. **Phase Angle ($\phi$):** The phase angle between voltage and current will be non-zero. For a lagging load (inductive), the current waveform lags behind the voltage waveform, resulting in a positive reactive power measurement. 3. **Power Measurement:** * **Real Power (P or KW):** Will be a positive, non-zero value, indicating that the load consumes real energy (due to the resistive component). * **Reactive Power (Q or KVAR):** Will be a positive, non-zero value, indicating that the load consumes reactive energy (due to the inductive component). In the context of standard power measurement questions where the answer is known to be inductive-resistive (Lagging PF): * The load consumes both Real Power ($P > 0$) and Reactive Power ($Q > 0$). * This combination signifies a load containing both resistive elements (consuming P) and inductive elements (consuming Q), characteristic of an **inductive-resistive load**. **Why the other options are incorrect:** * **B) a purely resistive load:** For a purely resistive load, the Power Factor (PF) would be exactly 1.0, and the Reactive Power (Q) would be zero. Since the load in question is inductive-resistive, it exhibits a reactive power component and a PF less than 1. * **C) a resistive-capacitive load:** This type of load is also known as a leading load. It would result in a Power Factor less than 1.0, but the Reactive Power (Q) measurement would be negative (or indicated as "LEAD" on the meter), as capacitors generate reactive power relative to the source. Since the correct load is inductive (lagging), this option is incorrect. * **D) a purely inductive load:** For a purely inductive load, the Power Factor (PF) would be exactly zero, and the Real Power (P) would be zero. Since the load consumes real power (P > 0) due to its resistive component, it cannot be purely inductive.