Polarity - In electricity, the condition of being positive or negative.
Reactance (subtransient Uscx %, for generator) - Relative measurement (%) of the internal impedance of an AC generator during harmonic phenomena. This reactance, also called the longitudinal subtransient reactance of the generator, is sometimes identified as X"d. For most common generators, the value ranges between 15 and 20%. It can drop to 12% for optimized systems and to 6% for special devices.
Hourly Rate (also see C-Rate) - A discharge rate, in amperes, of a battery which will deliver the specified hours of service to a given cutoff voltage.
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
C-Rate (also see Hourly Rate) - Discharge or charge current, in amperes, expressed in multiples of the rated capacity. For example, C/10 discharge current for a battery rated at 1.5 Ah is:
Voltage Depression - An abnormal drop in voltage below expected values during the discharge of a battery.
Protection index (IP) - Index indicating the capacity of an electrical device to resist environment conditions. It is made up of three digits (e.g. IP 205), each corresponding to a type of environmental risk. The higher the number, the greater the capacity to resist. First digit (0 to 6) - capacity to resist penetration by solid objects. Second digit (0 to 7) - capacity to resist penetration by liquids. Third digit (0, 1, 2, 3, 5, 7, 9) - mechanical strength.
