Attractive nuisances can create liability risks. Learn what a home attractive nuisance is and see the most common attractive nuisance examples.
In mathematics, the harmonic mean (sometimes called the subcontrary mean) is one of several kinds of average, and in particular one of the Pythagorean means. Typically, it is appropriate for situations when the average of rates is desired. The harmonic mean can be expressed as the reciprocal of the arithmetic mean of the reciprocals. As a simple example, the harmonic mean of 1, 2, and 4 is 3 1 1 + 1 2 + 1 4 = 1 1 3 ( 1 1 + 1 2 + 1 4 ) = 12 7 .
For this and other reasons, most experts in power system harmonics frown on using THD as a measure of harmonics. Other measures such as TDD (IEEE 519) or volts and amps make more sense. For example, the waveform above consists of 32.4 amps at 60 Hz, plus 25.4 amps at 180 Hz, plus 14.8 amps at 300 Hz, etc.