Metal Hydride - An intermetallic compound or alloy in which hydrogen has been absorbed; also, the negative electrode in a nickel-metal hydride battery.
Output (rated) - Apparent power Pn that the UPS can deliver under given load conditions (power factor = 0.8).
Charger - Device associated with the rectifier and used to supply the battery with the electrical power (DC current) required to recharge and/or float charge the battery, thus ensuring the rated backup time.
Earthing system - System for the interconnection and earthing of exposed conductive parts and neutral. There are three types of neutral system - IT, TN, TT.
Open-Circuit Voltage (OCV) - The difference in potential between the terminals of a cell when the circuit is open (no-load condition).
Transformer short-circuit voltage (Uscx %) - Relative measurement (%) of the internal impedance of a transformer. This short-circuit impedance is commonly called the short-circuit voltage because it is measured during a short-circuit test (shorted secondary winding subjected to a current set to In). For most common three-phase transformers, this value ranges between 3 and 6%.
Absorption - The taking up or retention of one material by another by chemical or molecular action.