Hertz - The standard unit of frequency. A frequency of one complete cycle per second is a frequency of one hertz.
Harmonic Sinusoidal - Term of the Fourier series expansion of a periodic function. The harmonic (or harmonic component) of the nth order is characterized by - Yn is the rms value of the given harmonic component, w is the angular frequency of the fundamental, related to frequency by - w = 2_f; phin is the phase angle of the given harmonic component at t = 0.
Harmonics (current and voltage) - All alternating current which is not absolutely sinusoidal is made up of a fundamental and a certain number of current harmonics which are the cause of its deformation (distortion) when compared to the theoretical sine-wave. For each current harmonic of order n and an rms value In, there is a voltage harmonic with an rms value Un. If Zsn is the voltage source output impedance for the harmonic of the nth order, then - Un = Zsn x In
Safety installation - Installation supplying electrical equipment which may have a direct effect on the safety of users and must therefore remain energized even in the event of a mains failure. In general, characteristics concerning the power supply and conditions for transfer to the safety source for such electrical equipment are covered by applicable regulations.
Energy Density - The ratio of the energy available from a battery to its volume (Wh/L) or weight (Wh/kg).
Absorption - The taking up or retention of one material by another by chemical or molecular action.
Cycle Life - The number of cycles under specified conditions which are available from a secondary battery before it fails to meet specified criteria as to performance.
