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Electrical Aspects
Published in Frank R. Spellman, The Science of Wind Power, 2022
An electric circuit includes: an energy source [source of electromotive force (emf) or voltage; that is, a battery or generator], a conductor (wire), a load, and a means of control (see Figure 8.20). The energy source could be a battery, as in Figure 8.20, or some other means of producing a voltage. The load that dissipates the energy could be a lamp, a resistor, or some other device (or devices) that does useful work, such as an electric toaster, a power drill, radio, or soldering iron. Conductors are wires that offer low resistance to current; they connect all the loads in the circuit to the voltage source. No electrical device dissipates energy unless current flows through it. Because conductors, or wires, are not perfect conductors, they heat up (dissipate energy), so they are actually part of the load. For simplicity, however, we usually think of the connecting wiring as having no resistance, since it would be tedious to assign a very low resistance value to the wires every time we wanted to solve a problem. Control devices might be switches, variable resistors, circuit breakers, fuses, or relays.
Superusers’ C-factors
Published in Randy Deutsch, Superusers, 2019
As you’ll sometimes hear Boomers and Gen-Xers tell it, if a project took four years from concept to realization, you worked on it for four years. That timeline’s got to be harder for the current generation coming in. “Oh, yeah. I see it,” says Hilda Espinal, CTO at CannonDesign “I see them getting excited about what’s the newest, coolest thing, and running out of patience about always doing the same thing, all the time, for extended periods.” Part of it is stick-with-it perseverance, some patience. But it is just as important that design technologists feel as though they have time – time to explore, time to inquire, time to search, and time even for downtime. A capacitor stores (electrical) energy and gives it off to the circuit when it’s needed. Call this quality capacity: having the capacity to take on another assignment whether or not you actually have the time to do so. Having capacity means there is always time and energy, because you’ll make it. A mindset, it’s less about multitasking, which is seldom productive, than working smart.
Transistor
Published in Muhammad H. Rashid, Ahmad Hemami, Electricity and Electronics for Renewable Energy Technology, 2017
As we will learn gradually, most applications of a transistor are for switching and for amplification. In switching, a transistor is used as a switch, meaning that it can turn on and off a device or part of a circuit. As for amplification, a transistor can be used as a voltage amplifier, a current amplifier, or a power amplifier. In both switching and amplification, there is an input signal to the transistor and an output signal from the transistor. For each signal (input and output), two connections are necessary, as shown in Figure 17.7. This figure symbolizes a transistor as an input-output device, each one with an internal resistor between the two terminals. When a signal is introduced to the input terminals, the corresponding output signal is generated and is available at the output terminals. Because a transistor has only three physical terminals to the outside world, in order to have two input lines and two output lines, two of the terminals can be assumed to be internally connected, through an internal resistor. In other words, one of the terminals must be shared between the input and the output.
Modeling the Interaction of Electrodynamic Fields to Circuit Elements
Published in IETE Journal of Education, 2018
A typical circuit comprises circuit elements (resistors, inductors, and capacitors) and sinusoidal sources (voltage or current) interconnected by conductors. Kirchhoff's voltage law (KVL) states that the voltage drops of the sources and circuit elements around any given loop sums to zero [20]. The relationship between the circuital phasor current I and the circuit element phasor voltage drop is well known: (1) for a resistor R (Ω): , (2) for an inductor L (H): , and (3) for a capacitor C (F): (see example circuit in Figure 2). Kirchhoff's law is applicable to electrically small circuits ( i.e. the sinusoidal current in a given loop has the same phase throughout the loop [21, 22]).