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For AC-operated devices (e.g. coaxial cable, loudspeakers), there may even be two power ratings, a maximum (peak) power rating and an average power rating. [5] [6] For such devices, the peak power rating usually specifies the low frequency or pulse energy, while the average power rating limits high-frequency operation. [5]
In some cases, an audio device may be measured by the total system power of all its loudspeakers by adding all their peak power ratings. Many home theater in a box systems are rated this way. Often low-end home theater systems' power ratings are taken at a high level of harmonic distortion as well; as high as 10%, which would be noticeable. [21]
High power LED current (peak 2.7 A) [5] 5 A One typical 12 V motor vehicle headlight (typically 60 W) 9 A 230 V AC, toaster, kettle (2 kW) 10 1: 10 or 20 A 230 V AC, Europe common domestic circuit breaker rating 15 or 20 A 120 V AC, United States, Canada and Mexico domestic circuit breaker rating 16.6 A 120 V AC, toaster, kettle (2 kW) 20 A
Modern Class AB amplifiers commonly have peak efficiencies between 30 and 55% in audio systems and 50-70% in radio frequency systems with a theoretical maximum of 78.5%. Commercially available Class D switching amplifiers have reported efficiencies as high as 90%. Amplifiers of Class C-F are usually known to be very high-efficiency amplifiers.
Unlike average power, which is the mean power output over a period, peak power represents the maximum power output at any given instant. This distinction is crucial in applications where signal peaks can significantly exceed the average power level. Peak power is a critical parameter in the field of radio frequency (RF) and telecommunications.
The voltage and frequency of electric power differs between regions. In much of the world, a voltage (nominally) of 230 volts and frequency of 50 Hz is used. In North America, the most common combination is 120 V and a frequency of 60 Hz. Other combinations exist, for example, 230 V at 60 Hz.
Power amplifier circuits (output stages) are classified as A, B, AB and C for linear designs—and class D and E for switching designs. The classes are generally based on the proportion of each input cycle (conduction angle) during which an amplifying device passes current. [2]
A lower rating will apply if multiple conductors are in proximity, since each contributes heat to the others and diminishes the amount of external cooling of the conductors. Depending on the type of insulating material, common maximum allowable temperatures at the surface of the conductor are 60, 75, and 90 °C, often with an ambient air ...