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Alternating Current (ac) Electronics
Published in Dale R. Patrick, Stephen W. Fardo, Electricity and Electronics Fundamentals, 2020
Dale R. Patrick, Stephen W. Fardo
Figure 2-3 shows several voltage values associated with ac. Among these are peak positive, peak negative, and peak-to-peak ac values. Peak positive is the maximum positive voltage reached during a cycle of ac. Peak negative is the maximum negative voltage reached. Peak-to-peak is the voltage value from peak positive to peak negative. These values are important to know when working with radio and television amplifier circuits. For example, the most important ac value is called the effective, or measured, value. This value is less than the peak positive value. A common ac voltage is 120 V, which is used in homes. This is an effective value voltage. Its peak value is about 170 V. Effective value of ac is defined as the ac voltage that will do the same amount of work as a dc voltage of the same value. For instance, in the circuit of Figure 2-4, if the switch is placed in position 2, a 10-V ac effective value is applied to the lamp. The lamp should produce the same amount of brightness with a 10-V ac effective value as with 10 V dc applied. When ac voltage is measured with a meter, the reading indicated is effective value.
Instruments and measurement
Published in Stephen Sangwine, Electronic Components and Technology, 2018
Voltage is probably the most frequently measured quantity in electronic engineering, and the need arises to measure both steady (or d.c.) voltages and time-varying voltage, of which sinusoidally varying (or a.c.) voltages are a very common case. Voltage is a measurement of electric potential — it indicates the potential energy of electric charge and is expressed in units of energy per unit of electric charge. Voltage is therefore expressed in joules per coulomb (J C−1), which, for convenience, is given the name volt (V). Voltage is a relative quantity — it must be measured relative to some reference potential. Usually the reference potential is denoted by 0 V and is quite often “mains” earth potential, that is, the potential of a conductor that is electrically connected by a low impedance to the body of the earth through the fixed wiring of a building or other location. Within an electronic circuit the 0 V rail may or may not be electrically connected to mains earth. The choice is not arbitrary and, among other things, safety must be considered, as discussed further in Chapter 11. Typically voltages from about 1 mV to 1 kV are routinely measurable with common instruments. Above a few kilovolts, care has to be taken to avoid flashover and special instruments are needed. Below 1 mV, electrical noise becomes a problem and measurements are not so straightforward.
Electrical, Electronic, and Electromechanical Systems
Published in Ramin S. Esfandiari, Bei Lu, Modeling and Analysis of Dynamic Systems, 2018
The voltage at a point in a circuit is a measure of the electrical potential difference between that point and a reference point called the ground. The unit of voltage is volt (V). If a point has the same electrical potential as the ground, it has a voltage of zero. For a two-terminal electrical element, the voltages at both ends are different. As shown in Figure 6.1, v1 and v2 denote the terminal voltages with respect to the ground, and () v=v1−v2
To Design an off Gird PV System for un electrified area of District Tharparkar, Pakistan
Published in International Journal of Green Energy, 2021
Kamlesh Kumar, Mahesh Kumar, Amir Mahmood Soomro
Assumptions taken for design: Inverter converts DC into AC power with efficiency of about 90%.Battery voltage used for operation = 12 volts.The combined efficiency of inverter and battery will be calculated as: combined efficiency = inverter efficiency × battery efficiency = 0.9 × 0.9 = 0.81 = 81%.Sunlight available in a day = 8 hours/day (equivalent of peak radiation.PV panel power rating = 40 Wp (Wp, meaning, watt (peak), gives only peak power output of a PV panel) A factor called „ operating factor‟ is used to estimate the actual output from a PV module. [The operating factor between 0.60 and 0.90 (implying the output power is 60 to 80% lower than rated output power) in normal operating conditions, depending on temperature, dust on module, etc.]
Efficient Power Flow Management in Hybrid Renewable Energy Systems
Published in IETE Journal of Research, 2023
J. Sheeba Jeba Malar, A. Bisharathu Beevi, M. Jayaraju
The energy storage system (ESS) controller manages the power generated by the solar, wind, and battery system in order to fulfill the instantaneous power demand during high non-linearities. A two-loop control system [28] is adopted in the proposed system as shown in Figure 1. The outer loop is voltage control loop, which is used to regulate dc bus voltage and battery voltage. The inner loop is the current control loop which is used to control battery, PV, and wind power variations by controlling power to and from the battery. The load voltage regulator helps the system to produce constant dc voltage irrespective of change in source and load.
Tungsten oxide as electrocatalyst for improved power generation and wastewater treatment in microbial fuel cell
Published in Environmental Technology, 2020
COD concentration of the anolyte before and after a batch cycle was measured by closed reflux colorimetric method [18]. The open circuit voltage (OCV) under no current flow condition and operating voltage (OV) at a resistance of 100 Ω for all the MFCs were measured using data acquisition/switch unit (Agilent Technologies, Penang, Malaysia) connected with a computer system. Power was calculated using the relation P = IV, where ‘P’ = power (in watts), ‘I’ = current (in amperes), ‘V’ = voltage (in volts). Current density and power density were calculated by dividing the current produced and power generated respectively by the surface area of the anode. Coulombic efficiency (CE) for every batch cycle was estimated using Equation (1).where I is current produced; M is the molecular weight of oxygen; v is the working volume of the anodic chamber of MFC; b is the number of electrons exchanged per mole of oxygen = 4; F is Faraday's constant = 96,485 C/mol; ΔCOD is the difference in the influent and effluent COD concentration after time t [19]. Polarization was performed after these MFCs reached a stable cell potential. During polarization, external resistance was varied from 40,000 to 10 Ω using resistance box (GEC05R Decade Resistance Box; Renown Systems, Kolkata, India). The internal resistance of the MFC was estimated from the slope of the voltage vs. current curve. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) were also carried out using electrochemical workstation (Autolab PGSTAT 302N potentiostat, Metrohm, Utrecht, the Netherlands). CV is the most widely used technique to understand the mechanism of oxidation and reduction reactions in fuel cells [20]. A frequency range of 100 kHz–1 mHz with an AC signal of 10 mV amplitude was used during EIS study to determine the different components of the internal resistance of different MFCs [21]. Frequency response analyser (FRA, Metrohm, Utrecht, the Netherlands) was connected through the potentiostat to the MFCs for measurement. The frequency response data were simulated using NOVA 1.9 software and the corresponding equivalent circuit was fitted. CV analysis was performed from −1 to +1 V at a scan rate of 1 mV/s with modified carbon felt electrodes as a working electrode [22]. Ag/AgCl was used as a reference electrode (+205 mV vs. standard hydrogen electrode) and platinum rod was used as a counter electrode [23]. LSV was also performed similarly as that of CV in the potential range of −0.6 to +0.6 V. The current response against different applied voltages for both CV and LSV were recorded with NOVA 1.9 software. EIS was performed using ultrapure water as electrolyte and whereas for CV and LSV phosphate buffer solution (50 mM) of pH 7 was used.