Glossary & Terms
| Term Definition | ||
| A | ||
| Alternating Current | Electrical current which periodically reverses direction, usually several times per second | |
| Ampere | The measurement unit for electrical current | |
| Arc Flash | An arcing fault is the flow of current through the air between phase conductors or phase and neutral or ground. An arcing fault can release tremendous amounts of concentrated radiant energy at the point of the arcing in a small fraction of a second resulting in extremely high temperatures, a tremendous pressure blast, and shrapnel hurling at high velocity. | |
| Attenuation | A reduction in signal strength during transmission. | |
| Automatic Transfer Switch | A switch that automatically transfers electrical loads to alternate or emergency-standby power . | |
| B | ||
| Backbone | Another term for bus, the main wire that connects nodes. | |
| Battery | Two or more cells connected together electrically. Cells may be connected in series or parallel, or both, to provide the required operating voltage and current levels. | |
| Battery Nominal Voltage | The nominal voltage of one cell multiplied by the number of cells in the battery. | |
| Bend Radius | The radius of curvature that a cable can bend without suffering damage and reduced performance. | |
| Black Hole | Slang term for a router that goes down (offline) and whose absence goes undetected by other routers on the network. | |
| Blades | Blade Servers | |
| Bridge | A device that connects two local-area networks (LANs), or two segments of the same LAN that use the same protocol. | |
| C | ||
| C Rate | A term used primarily outside the US, to express battery cell capacity (at specified references), or charge and | |
| Cable Tray | A rigid structural system used to support cables and raceways. Types of cable trays include ladder, ventilated trough, ventilated channel, and solid bottom. | |
| Capacitor | Any AC circuit element possessing the property of capacitance (i.e., the ability to store a charge). | |
| Change Management | A methodology of planning and coordinating, and communicating about activities in the data center. | |
| Characteristic Impedence | The opposition that a cable or component gives to the flow of an alternating electrical current. | |
| Charge | In batteries, it is the conversion of electrical energy into chemical energy within a secondary cell. | |
| Chilled Water System | A type of precision cooling system widely used in mid-sized to large IT environments. A chilled water system uses water as a cooling medium. Cold water is pumped from a chiller to computer room air handlers designed to cool the space. A chilled water air conditioner can be thought of as similar to a car radiator with a fan, with hot air being cooled by being blown through a cool radiator. In a chilled water system cooling an IT facility, the chilled water may be provided as a utility in the building, or special dedicated water chillers may be installed. | |
| Chiller | A device used to continuously refrigerate large volumes of water. A chiller uses the refrigeration cycle to produce large volumes of chilled water (typically at 45-48°F / 7-9°C) that is distributed to Computer Room Air Handlers (CRAH) units designed to remove heat from the IT environment. | |
| Circuit Breaker | A device that can be used to manually open or close a circuit, and to automatically open a circuit at a predetermined level of over current without damage to itself. | |
| Clamping time | The response time for a surge suppression device, i.e. the time it takes to respond to the voltage climbing above the clamping level. | |
| Closed Transition Transfer | Closed transition transfer momentarily parallels the two power sources during transfer from either direction. | |
| Cold Site | A disaster recovery facility that provides only the physical space for recovery operations while the organization using the space provides its own hardware and software systems. | |
| Colocation | Colocation - also colocated, collocated, collocation - is a type of web hosting where the customer's server equipment is hosted in the web hosting provider's data center. | |
| Common Mode Noise | Noise that exists between the power conductors, hot and neutral, with respect to the ground conductor. | |
| Compartmentlization | Various subsystems within the power distribution and backup sustem are physically separated. | |
| Compressor | The compressor is an essential component in the refrigeration cycle that uses mechanical energy to compress or squeeze gaseous refrigerant. | |
| Computational Fluid Dynamics | A manner in which air flow and air temperature anywhere in a computing environment can be predicted using a computer and software. This is achieved by creating a detailed model of the room dimensions, equipment and cooling system on a computer using a software package. The software then uses the computer to solve a series of complex mathematical equations resulting in a virtual representation of the environment with detailed temperature and air flow data at any given point. | |
| Condenser Coil | A condenser coil is one means of heat rejection commonly used in an air conditioning system. It is typically located on an outdoor pad or on a rooftop and looks like an automobile radiator in a cabinet. It is usually hot to the touch (120°F / 49°C) during normal use. Its function is to transfer heat energy from the refrigerant to the cooler surrounding (usually outdoor) environment. The related Dry Cooler or Fluid Cooler serves the same purpose of heat rejection and physically appears similar, with the difference that the condenser coil uses hot refrigerant which changes from a gas to liquid as it move through the coil, whereas the Fluid Cooler uses hot liquid such as water or a water-glycol mix. | |
| Convection | A mode of heat transfer in which heat energy is transferred from an object to moving fluid such as air, water, or refrigerant. The heat sink of a computer processor is an example of heat transfer by convection. Convection is one of the three forms of heat transfer, which also include Conduction and Radiation. | |
| Cooling Tower | A heat rejection method that transfers heat energy from a data center or IT room to the outside atmosphere via the evaporation of water. In a cooling tower, water is sprayed onto a high surface-area packing material as large volumes of air are drawn across through the structure. The net effect of this process is that a small portion of the water circulated through the cooling tower evaporates into the outside atmosphere. The remaining water (now cooler) is collected at the bottom of the | |
| Critical Load | Equipment that must have an uninterrupted power input to prevent damage or loss to a facility or to itself, or to prevent danger of injury to operating personnel. | |
| Crosstalk | When the signal carried along one set of cable (metal) wires interferes with the signal of a nearby set. | |
| Current | The flow of electricity in a circuit. The term current refers to the quantity, volume or intensity (1) of electrical flow, as opposed to voltage, which refers to the force or "pressure" causing the current flow. | |
| D | ||
| Data Mart | A database, or collection of databases, designed to help managers make strategic decisions about their business. | |
| Dual Corded Equipment | Equipment with 2 power supplies | |
| E | ||
| F | ||
| G | ||
| Galvanic Solation | Isolation of the Neutral Wire | |
| H | ||
| Heat Sink | A component designed to lower the temperature of an electronic device by dissipating heat into the surrounding air. | |
| Hot Plugging | The ability to add and remove devices to a computer while the computer is running and have the operating system automatically recognize the change. | |
| Hot Site | A fully operational offsite data processing facility equipped with both hardware and system software to be used in the event of a disaster or for disaster recovery. | |
| HUB | A common connection poitn for devices in a newtwork. | |
| I | ||
| Inrush current | The initial surge of current experienced before the load resistance of impedance increases to its normal operating value. | |
| Inter-System Ground Noise | Ground voltage differences between interconnected devices. Exists between ground wires suppling interconnected computers. | |
| IP | Internet Protocol | |
| Interoperability | The ability of a system to use parts or data from another system. | |
| Inverter | Inverter | |
| J | ||
| K | ||
| L | ||
| M | ||
| N | ||
| Noise | Transient voltage event | |
| O | ||
| P | ||
| Power Factor | Ratio of the WATT to VA. | |
| Proximity Effect | When a power transformer carries harmoic currents | |
| Q | ||
| R | ||
| Regenerated Neutral | Isolation of the neutral wire | |
| Relay | A mechanical switch that is held to one side by a magentic force | |
| Router | A device that forwards data packets along networks. | |
| S | ||
| Sarbanes-Oxley Act | The Sarbanes-Oxley Act was signed into law on 30 July 2002 by President Bush. The Act is designed to oversee the financial reporting landscape for finance professionals. Its purpose is to review legislative audit requirements and to protect investors by improving the accuracy and reliability of corporate disclosures. The act covers issues such as establishing a public company accounting oversight board, auditor independence, corporate responsibility and enhanced financial disclosure. It also significantly tightens accountability standards for directors and officers, auditors, securities analysts and legal counsel. The law is named after Senator Paul Sarbanes and Representative Michael G. Oxley. | |
| Separately Derived Source | Isolation of the neutral wire | |
| T | ||
| Tier | A four tier system that provides
a simple and effective means for identifying different data
center site infrastructure design topologies. The Uptime
Institute's tiered classification system is an industry
standard approach to site infrastructure functionality addresses
common benchmarking standard needs. The four tiers, as classified
by The Uptime Institute include the following: Tier
1: composed of a single path for power and cooling distribution,
without redundant components, providing 99.671% availability.
|
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| Transformer | TAn electromagnetic device that changes the volage of alternating current electricity | |
| U | ||
| V | ||
| Virtualization | In computing, virtualization means to create a virtual version of a device or resource, such as a server, storage device, network or even an operating system where the framework divides the resource into one or more execution environments. | |
| W | ||
| X | ||
| Y | ||
| Z | ||