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Basic Concepts about Electricity
Published in Dorothy Gerring, Renewable Energy Systems for Building Designers, 2023
In the USA the typical power delivered to buildings is AC 120V/240V at 60Hz (hertz). Other countries use different AC voltages at 50Hz. Hertz is the unit of frequency and its unit is one cycle per second. The higher the hertz number is, the shorter the sine wave is. Most countries use AC power, although there are many items such as rechargeable batteries, LED lighting, computers, and smart phones that all use DC power. If you have a piece of electronic equipment that has a large plug adaptor (or a box near the plug) then it is changing (transforming) the AC power from the outlet into DC power.
Operational Power Control Systems
Published in Dale R. Patrick, Stephen W. Fardo, Brian W. Fardo, Electrical Power Systems Technology, 2021
Dale R. Patrick, Stephen W. Fardo, Brian W. Fardo
The power system frequency used in the United State is 60 hertz or 60 cycles per second. However, there are specific applications that require other frequencies in order to operate properly. Mechanical frequency converters may be used to change an incoming frequency into some other frequency. Frequency converters are motor/generator sets that are connected together or solid-state variable frequency drives.
Operational Power Control Systems
Published in Stephen W. Fardo, Dale R. Patrick, Electrical Power Systems Technology, 2020
Stephen W. Fardo, Dale R. Patrick
The power system frequency used in the United State is 60 hertz, or 60 cycles per second. However, there are specific applications that require other frequencies in order to operate properly. Mechanical frequency converters may be used to change an incoming frequency into some other frequency. Frequency converters are motor/generator sets that are connected together, or solid-state variable frequency drives.
The dependence of rubber tackiness on separation speed
Published in The Journal of Adhesion, 2023
Figure 3 summarizes the linear viscoelastic behaviors of various elastomers, oil-extended rubbers and particle-filled rubber compounds used in this study. Figures 3a) and 3b) depict specifically the viscoelastic behaviors of the neat and oil-extended PIPs. At low frequencies, all the neat polymers and oil-extended polymers exhibit typical Newtonian-fluid behavior, where G” scales as ω1, G’ scales as ω2, and G” exceeds G’. At high frequencies, they all display entanglement G’-plateaus, where G’ surpasses G” and G” passes through a minimum. As can be seen from Figures 3a) and 3b), the crossover frequency ωt at which G’ crossovers G” is a function of the molecular weight Mn and the oil content. Increasing the molecular weight or decreasing the oil content generally decreases the crossover frequency ωt. Here, the angular frequency ω = 2πf and f is the Hertz frequency.