Laboratory Experiment, Lab Reports of Electrodynamics

Download Laboratory Experiment and more Lab Reports Electrodynamics in PDF only on Docsity! ELEN112L – ELECTRICAL CIRCUITS 2 LABORATORY EXPERIMENT NO. 2 1 | PAGE LABORATORY REPORT NO.: 2 Power in AC circuits and Power Factor Correction OBJECTIVES: 1. Conduct experiments on electrical measuring instruments and devices 2. Determine real, reactive, and apparent power in RC, RL, and RLC circuits. MATERIALS: • AC source • Resistors • Inductors • Capacitor • Desmos.com DISCUSSION & PROCEDURE: Real power (P), measured in watts and dissipated in an RC, RL, or RLC load circuit for ac sinusoidal voltages and currents, is exclusively dissipated in the resistance portion. In a perfect reactive element, such as a capacitor or inductor, no actual power is lost. Energy is stored during one half of the ac cycle in a reactive element and released (sourced) during the other. Reactive power (Q), which has the units of var, is the term for the power contained in a reactive element (volt-ampere reactive). Large ac motors and other inductive loads typically require power factor adjustment. It is beneficial to compensate for the inductance by bringing the power factor as near to unity as feasible since a power factor of 1 (unity) requires less peak current. By doing this, we get the perceived power and true power very nearly equal (S). By joining a capacitor in parallel with the inductive load, the power factor is adjusted. The Following formulas are needed for computing power factor correction: Formula name Formula Reactance 𝑋𝐿 = 𝑗2𝜋𝑓𝐿 𝑎𝑛𝑑 𝑋𝑐 = − 1 𝑗2𝜋𝑓𝐶 Voltage V = IZ Apparent Power AP = VrmsIrms Real Power RP = 𝐼2R Reactive Power RP = 𝐼2𝑋𝑙 Power Factor Pf = TP 𝐴𝑃 𝑜𝑟 = 𝑐𝑜𝑠𝑖𝑛𝑒∅ Capacitor need to pf unity Xc = |V|2 − Q Table 1: Formulas needed for in-power factor correction. The power used by a typical electrical system is shown in this diagram. The leading power factor of the capacitive system is represented by the positive angle, while the inductive system is represented by the negative angle (lagging power factor). The current and voltage in an AC system are wave signals that may or may not be out of phase with one another. Either the voltage or the current will arrive first if they are out of phase with one another. If the voltage waveform appears before the current waveform, the current will lead the voltage by a little amount of angle and demand more power. Figure 1: Leading Power Factor ELEN112L – ELECTRICAL CIRCUITS 2 LABORATORY EXPERIMENT NO. 2 2 | PAGE The system is an inductive one and has a trailing power factor, however, if we reverse the scenario and the voltage arrives first, the voltage in this case lags behind the current by several electrical degrees. Figure 2: Lagging Power Factor Our electrical system might become more effective with power factor adjustment. Our electric meter’s function is based on the amount of current that flows through them. MEASUREMENTS & RESULTS: Sample Problem No. 1: A 15 resistance and a 26 inductive reactance are the components of an RL series circuit. Calculate: If a circuit has a 5-ampere current flowing through it: Figure 3: Sample problem circuit 1. supply voltage 𝑉𝑆 𝑉𝑅 = 𝐼 × 𝑅 = 5 × 15 = 75𝑉 𝑉𝐿 = 𝐼 × 𝑋𝐿 = 5 × 26 = 130 𝑉 𝑉𝑆 = √𝑉𝑅 2 + 𝑉𝐿 2 = √752 + 1302 𝑉𝑠 = 150 𝑉 𝑟𝑚𝑠 2. the phase angle between the circuit current and the supply voltage. 𝑐𝑜𝑠ϕ = 𝑉𝑅 𝑉𝑆 𝑐𝑜𝑠ϕ = 75 150 = 0.5 𝜙 = 60° 3. Create the phasor diagram as a consequence.