This paper aims at analyzing some important aspects related to ideal and nonideal electrical systems. In this way, the analyses are presented in the theoretical form, followed by typical examples from field measurements. It is usual to associate some harmonic orders with specific equipment operation, like a noncontrolled 6 pulse rectifier, a motor, a generator, etc. These structures define characteristic harmonics in ideal electrical operation and occur in couple association. Depending on the similarity degree in the couple members, these harmonics had been called using a biological correlation, as univitelline and bivitelline. Similarly, there are differences in the same harmonic order phases that can be qualified according to a chemical analogy, namely in acid and alkaline harmonics. There are, also, differences between stator and rotor harmonics.