HP BL260c Power basics for IT professionals - Page 38

High-line voltage: In a commercial setting, power that is 180-264V AC (200-240V AC nominal rating). High-line voltage is common in commercial applications in North America and is the AC appliance standard in the majority of other countries. Also referred to as high voltage. Hot: A live conductor that is carrying voltage. When a light switch is turned on, the non-neutral wire leading to the light becomes "hot." Hot aisle: The data center aisle(s) where the greatest heat flow travels from the servers toward the airconditioning units. Using best practices, hot aisles alternate with cold aisles in data centers. Hz: hertz ICC: International Color Code IEC: International Electrotechnical Commission IEEE: Institute of Electrical and Electronics Engineers Impedance: The resistance to current, measured in ohms. Inductance: The ability of a coil to store energy and resist change in electrical current, measured in henries. See: Henry Induction: The transfer of power from one device to another via an electromagnetic field. Inner conductor colors: Hot/Neutral/Ground are black/white/green in North America, but they are brown/blue/green-with-yellow internationally (ICC). Input voltage: The power that a server or power supply can accept-low-line (120V) or high-line (208V/240V) AC. Inrush current: A high, momentary influx of current during the initial startup of a server (or an additive input current in the case of multiple servers), due to the capacitive properties of components in the power supply. Inrush current can be several times greater than the operating current, thereby tripping fuses or circuit breakers. All HP power supplies provide the capability to limit inrush current. Institute of Electrical and Electronics Engineers (IEEE): An international non-profit, professional organization for the advancement of technology related to electricity and the largest technical professional organization in the world. Insulation: A material of high electrical resistance used to keep current from going where it is not supposed to go. Wires running together such as in-line cords are covered with insulation to prevent arcing between conductors. Insulation is also commonly used in electric circuits when components are placed so close to each other that short circuits could occur. Intelligent management: HP software enables controlled power-on and power-off events and provides reporting on the power available versus the power consumed. Interference: An unwanted mix of electrical signals (usually associated with electrical noise). International Color Code (ICC): The international standard for inner conductor colors of electrical wiring. See Inner conductor colors. International Electrotechnical Commission (IEC): An international standards organization that deals with electric, electronic and other technical standards through its membership of (currently 60) national standards bodies. (For the IEC website, see http://www.iec.ch) J: joule Jacket: An extruded layer of insulation over a wire or group of cables. Joule (J): A unit of measurement of energy. A joule (rhymes with tool) is the energy needed to produce one watt continuously for one second. 38