Distortion (individual) - Ratio between the rms value of an nth order harmonic and the rms value of the fundamental.
Gravimetric Energy Density - The ratio of the energy output of a cell or battery to its weight (Wh/kg). This term is used interchangeably with specific energy.
Micro-outage (or micro-interruption) - Total loss in the supply of power for 10 ms.
UPS (Uninterruptible Power supply) - An electrical device providing an interface between the main power supply and sensitive loads (computer systems, instrumentation, etc.). The UPS supplies sinusoidal AC power free of disturbances and within strict amplitude and frequency tolerances. It is generally made up of a rectifier/charger and an inverter together with a battery for backup power in the event of a mains failure.
Closed-Circuit Voltage (CCV) - The potential or voltage of a battery when it is discharging or charging.
Frequency - The repetition of cycles measured in Hz. 60 Hz is the standard frequency in the U.S. 50 Hz is the standard frequency in other parts of the world. 60 Hz = 60 cycles per second.
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
