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Foundations of Electrical Systems
Published in Richard Cadena, Electricity for the Entertainment Electrician & Technician, 2021
Alternatively, if you have a multimeter, you can measure the voltage and current for either the entire system or an individual component and then calculate the “apparent power” by multiplying the two values. The units measure of apparent power is not watts, but volt-amps (VA). For example, the specifications for a Clay Paky Mythos list the apparent power at 700 VA at 230 V and 50 Hz. Apparent power is not what we ordinarily think of as “power,” but it is related to it by way of something called power factor. Power factor is a measure of how much of the current being drawn by the system or by a load is being converted to light, sound, heat, or motion compared to the apparent power. We'll discuss apparent power and power factor later on in Chapter 6.
Motors, Drives, and Electric Energy Management
Published in Stephen A. Roosa, Steve Doty, Wayne C. Turner, Energy Management Handbook, 2020
Roger G. Lawrence, K.K. Lobodovsky
Power factor (pf) is the mathematical ratio of active power (W) to apparent power (VA) pf=active powerapparent power=W × Cosθ
Power System Fundamentals
Published in Stephen W. Fardo, Dale R. Patrick, Electrical Power Systems Technology, 2020
Stephen W. Fardo, Dale R. Patrick
Since reactive circuits cause changes in the method used to compute power, the following described techniques express the basic power relationships in AC circuits. The product of voltage and current is expressed in volt-amperes (VA) or kilovolt-amperes (kVA), and is known as apparent power. When meters are used to measure power in an AC circuit, apparent power is the voltage reading multiplied by the current reading. The actual power that is converted into another form of energy by the circuit is measured with a wattmeter. This actual power is referred to as true power. Ordinarily, it is desirable to know the ratio of true power converted in a circuit into apparent power. This ratio is called the power factor and is expressed as: pf=PVA
Design, simulation and optimisation of a novel low ripple outer-rotor switched reluctance machine for variable speed application
Published in International Journal of Electronics, 2023
Omid Khodadadeh, Hassan Moradi CheshmehBeigi, Mohammad Hossein Mousavi
Various design strategies of SRMs have been explored in the past decades, which were based Inner-Rotor SRM (IRSRM) and Outer-Rotor SRM (ORSRM). The competitive superiority of the SRM compared to other electric machines is lack of magnets or brushes, simple and robust structure, especially in variable and high-speed applications. However, SRMs are capable of operating at very low speeds and very high torque densities. The most common SRM is the IRSRM. On the other hand, an ORSRM design has several benefits compared to an IRSRM in applications with high torque requirements. With ORSRM, it is possible to increase the torque per ampere ratio and hence reduce the volt-ampere requirements of the converter. Many studies have published the outer-rotor design for other machine types and applications like outer-rotor permanent magnet generator for directly coupled wind turbines (Chen et al., 2000), an external Rotor V-shape permanent magnet machine for E-Bike application (Yang et al., 2018), an external-rotor direct-drive E-bike SRM (Howey et al., 2020) and SR motor drive with outer rotor for the air conditioner fan (Chen & Gu, 2012). In Ma et al. (2018), an analytical method for calculating the no-load magnetic field of outer rotor permanent magnet brushless direct current motor (PMBLDCM) was used as the in-wheel motor of electric vehicles in the stator static coordinate and the rotor motion coordinate.
Single-stage three-phase boost power factor correction circuit for AC–DC converter
Published in International Journal of Electronics, 2018
Haitham Z. Azazi, Sayed M. Ahmed, Azza E. Lashine
Diode rectifiers are usually utilised in the power converter circuits as an interface with the electric utility in most of the power electronics applications (Yao, Meng, Bo, & Hu, 2016). Bridge rectifier operation leads to a distortion in the input current, generates harmonics in the AC power source and causes various problems (Zhang, 2009). A number of problems in the sensitive electronic equipment and distribution are produced because of the non-sinusoidal input current drawn by the rectifiers. This operation also leads to a distortion in the supply voltage. Therefore, it requires high values of volt–ampere rating of the generator, transformer and transmission lines. The result of this problem is a high total harmonic distortion (THD) and malfunctioning of the sensitive electronic equipment (Ming, 2004).
Wide Range Reactive Power Compensation for Voltage Unbalance Mitigation in Electrical Power Systems
Published in Electric Power Components and Systems, 2022
Jasim A. Ghaeb, Malek Alkayyali, Tarek A. Tutunji
Many disadvantages arise up with the voltage unbalance such as the excessive power losses and heating in the induction motors [8], reduction of efficiency for transformers, cables, and lines [9] and system instability [10]. The Static Volt-Ampere-Reactor Compensator (SVC) was employed to balance the electrical power system. The static compensator can be considered as an adjustable shunt susceptane to provide the required amount of lagging-leading of reactive power in to improve the stability of the system [11, 12]. In this case, a controller is added to determine the individual number of capacitors or the amount of inductance for maintaining voltage regulation and voltage balancing in the system. The two most widely used SVC devices are the TCR and TSC.