RMS Voltage - The range of usable voltage + or - 170 VAC.
Voltage-Keyed - A system which incorporates a mechanical identifier on batteries and devices to ensure only batteries of the correct voltage are connected to the device.
Gassing - The evolution of gas from one or more of the electrodes in a cell. Gassing commonly results from local action (self-discharge) or from the electrolysis of water in the electrolyte during charging.
Constant Current Discharge - A battery discharge regime whereby the current drawn during the discharge remains constant.
Cutoff Voltage (also see End Voltage) - The battery voltage at which the discharge is terminated. The cutoff voltage is specified by the battery manufacturer and is generally a function of discharge rate.
Fourier theorem - Theorem stating that any non-sinusoidal periodic function (frequency f) may be represented as a sum of terms (series) made up of - n a sinusoidal term with frequency f, called the fundamental frequency, n sinusoidal terms with frequencies that are whole multiples of the fundamental frequency, (harmonics), n a possible DC component where n is a whole number. n = 1 corresponds to the fundamental, n > 1 to the harmonic of the nth order.
Cubicle (single UPS unit) - Cubicle containing a rectifier/charger, an inverter and a bypass. Connected to a battery, it operates alone, forming a single UPS. Compare with Cubicle (parallel UPS unit).