1.1.5 Power factor is defined as the ratio of true power to apparent power. 1.1.6 Three-phase loads can be connected in either star/star or delta/delta. full cycle average value represents the average value of all mid-ordinates taken over a 1.1.8 In any unbalanced three-phased load the impedance of each phase (Zp) is not equal. 1.1.9 Three-phase loads can be classified as either balanced or unbalanced. 1.1.10 In a purely resistive circuit, the voltage is always in phase with the current. Draw the wave form and vector diagram of a purely resistive circuit.

To illustrate the concepts of a purely resistive circuit, we will draw both the waveform and the vector diagram. Let's break this down step by step. ### Step 1: Understanding a Purely Resistive Circuit In a purely resistive circuit: - The voltage (V) and current (I) are in phase, meaning they reach their maximum and minimum values at the same time. - The power factor is 1, as all the power is true power (no reactive power). ### Step 2: Waveform of a Purely Resistive Circuit The waveform of voltage and current in a purely resistive circuit can be represented as sinusoidal waves. Since they are in phase, the peaks and zero crossings of both waveforms will align. 1. **Voltage Waveform (V)**: This is a sine wave that oscillates between a maximum positive value and a maximum negative value. 2. **Current Waveform (I)**: This is also a sine wave that matches the voltage waveform in terms of timing. ### Step 3: Vector Diagram of a Purely Resistive Circuit In the vector diagram: - The voltage vector (V) is represented along the horizontal axis. - The current vector (I) is also represented along the same axis since they are in phase. - The angle (φ) between the voltage and current vectors is 0 degrees. ### Step 4: Drawing the Waveform and Vector Diagram #### Waveform - The x-axis represents time. - The y-axis represents voltage and current. ``` Voltage (V) and Current (I) Waveform | / \ / \ | / \ / \ | / \ / \ |-------/-------\----/-------\------- Time | / \ / \ | / \/ \ | / \ |---/ \--- ``` #### Vector Diagram ``` I | | V |-------> | | +---------------------> Time ``` ### Conclusion In a purely resistive circuit: - The voltage and current waveforms are sinusoidal and in phase. - The vector diagram shows both voltage and current vectors aligned along the same axis, indicating that they are in phase with each other. This representation helps in understanding the behavior of purely resistive circuits in electrical engineering.