Data Center Design by ARISTOS INTERNATIONAL, INC.

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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.

As-built

A construction document illustrating how a building was constructed.

Automatic Transfer Switch (ATS)

A switch that automatically transfers electrical loads to alternate or emergency-standby power sources.

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 Back Up

See UPS

BOM

Bill of Materials

Bonding

The permanent joining of metallic parts to form an electrically conductive path that will ensure electrical continuity and the capacity to conduct any current to be present in a safe manner.

BTU

British Thermal Unit. BTUs are typically used to rate air conditioners (and some heaters). One BTU is defined as the energy required to increase the temperature of one pound of water by one degree Fahrenheit. To convert from BTUs to KWs: use 1 watt = 3.4129BTUs.

CFM

The abbreviation for cubic feet per minute. CFM is used to measure the flow of air through a delivery system or space.

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.

Closed Transition Transfer

Closed transition transfer momentarily parallels the two power sources during transfer from either direction.

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. Typically, the web hosting provider is responsible for providing power and connectivity, the customer is responsible for all work on the server and all of the data on the server.

Commissioning

A quality assurance-based process used to uncover deficiencies in design or installation via field verification. A formal review and integration of all project expectations during planning, design, construction, and occupancy phases by inspection and functional performance testing, oversight, and record documentation.

Computational Fluid Dynamics (CFD)

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.

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 cooling tower.

Coordination Study

To ensure that personnel and equipment are protected by establishing proper interrupting ratings and maximize power system selectivity by isolating faults to the nearest protective device, and avoid nuisance operations that are due to transformer inrush or motor operations.

CRAC

Computer room air conditioner

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.

CWR

The abbreviation for chilled water return, the term used for all piping intended to return chilled water from room air handlers to the chiller.

CWS

The abbreviation for chilled water supply, the term used for all piping intended to deliver chilled water from the chiller to the room air handlers.

Data Center

A location with specifically designed electrical and mechanical systems used to house large server processing systems and related equipment.

Dehumidification

Remove moisture from air by drawing it over a refrigerated coil with a fan. Since the saturation vapor pressure of water decreases with decreasing temperature, the water in the air condenses, and drips into a collecting area or is pumped to a drain. The air is then reheated by the warmer side of the refrigeration coil. Dehumidification is typically not desired in a data center but occurs anyway when the return air is low enough in temperature so that the dew point is reached as the air passes through the air conditioner.

Digital Generator Paralleling Control

An equipment manufacturing process that replaces traditional third party switches and multiple hardwired control modules with an integrated paralleling switch installed in the generator connection box, removing the cost and space of external switchgear. a "plug and play" digital control module manages speed governing, voltage regulation, generator alarm and monitoring, synchronizing, load sharing and protection-at each generator removing the hardwired maze of different manufacturers' analog and digital controllers. In addition the high cycle-rated contactor paralleling switch is specifically designed for switching power circuits, rather than an over-current protective device. The paralleling switch is mounted directly the generator and the paralleling switch is cabled typically to a generator distribution panel, replacing the functionality of the generator bus bar inside traditional switchgear.

Discharge Rate

The rate, in Amperes or Watts, at which current is delivered by a battery.

Double Interlock Pre-Action Fire Sprinkler

Air or nitrogen is used to pressurize the dry pipe fire sprinkler system. The purpose is to first monitor piping for leaks and second to hold water from system piping in the event of inadvertent detector operation. See Pre-Action Fire Sprinkler.

Down Flow

An air conditioner or air handler that discharge air in a downward direction mainly used on raised floors.

Downtime

A period of time, or a percentage of a time span, that a system is unavailable or offline. This is usually a result of the system failing to function because of an unplanned event, or because of routine maintenance.

Dry-type transformer

Transformers that do not use oils or cooling fluids and rely on the circulation of air around the coils to provide required cooling.

Economizer

An additional cooling coil installed into glycol-cooled air conditioning unit to provide free cooling in cold climates. The economizer coil contains cold glycol circulating directly from the fluid cooler when atmospheric conditions allow.

Emergency Power Off (EPO )

A single disconnecting means for all power required within a NEC 645 rated space.

Emergency Power system

When regular power systems fail, a system that may include generators and other apparatus will provide backup power and lighting during an outage.

Fault Current

The current that flows as a result of a short-circuit condition.

Floor tile

Part of a raised floor system, the floor tile is a removable component that is commonly 2ft x2ft. Floor tiles are made of hollow metal or filled with concrete or wood.

Fluid Cooler

A system consisting of coils and fans to used transfer heat energy from a flowing glycol stream to the outside atmosphere.

Free Cooling

A practice where the outside atmosphere is used to directly provide cooling via air free cooling or water free cooling. Water uses an additional cooling coil containing cold glycol circulating directly from the fluid cooler when atmospheric conditions allow. Air introduces cold outside air directly into the interior when atmospheric conditions allow.

Glycol

Ethylene glycol and water used as a heat removal medium. The glycol mixture is resistant to freezing in cold climates. See Glycol-Cooled System.

Glycol cooled system

A type of precision cooling system widely used in critical environments of all sizes. In a glycol system the air conditioner absorbs heat from the air and removes it from the room in the form of heated liquid water/glycol solution. The heated liquid flows via pumps and piping system to an outdoor radiator and fan where the heat is expelled.

Green Data Center

Data Centers being built considering energy efficiency, environmental impact, and sustainability.

Ground

A conducting connection, whether intentional or accidental by which an electric circuit, or equipment, is connected to the earth or some conducting body that serves in place of the earth.

Ground Fault

An undesired current path between ground and an electrical potential.

Harmonic Distortion

A percentage that refers to any single harmonic or to the total waveform, in which case it is referred to as "total harmonic distortion" (THD).

Hot Aisle / Cold Aisle

An organized layout in which parallel aisles of equipment enclosures are arranged with rack fronts always facing rack fronts and rack rears always facing rack rears. This ensures separation between cooling air in the "cold" aisle entering the front of the racks and warm exhaust air leaving the back of the racks in the "hot" aisle. Separation of cooling air and exhaust air results in higher cooling system efficiencies and the ability to cool higher power densities in the computing environment.

Hot Gas Line

A refrigerant line used to connect a compressor to a condensing coil in an air conditioning system.

Humidification

Often necessary in colder climates where continuous heating will make the air drier, resulting in increased static electricity. Various types of humidification are be used: Evaporative: dry air blown over a reservoir will evaporate some of the water. The rate of evaporation can be increased by spraying the water onto baffles in the air stream. Vaporizer: steam or vapour from a boiler is blown directly into the air stream. Spray mist: water is diffused either by a nozzle or other mechanical means into fine droplets and carried by the air.

Humidifier

The device used to provide humidification. The moisture is usually added to the air stream exiting the air conditioner or air handler.

HVAC

An abbreviation for Heating, Ventilation and Air Conditioning. Sometimes an "R" is shown at the end to represent refrigeration.

IEEE

Institute of Electrical and Electronics Engineers. Pronounced "eye-triple-E", this non-profit U.S. engineering organization develops, promotes, and reviews standards within the electronics, computer and electric power industries.

Infrared Scanning

Thermo graphic testing is used to locate defects and potential failures in electrical equipment by scanning for abnormal hot spots and heating patterns.

Inrush Current

The initial surge of current experienced before the load resistance of impedance increases to its normal operating value.

Inverter

A device that converts the battery DC output to AC.

Kilovolt (kVA)

Thousand VA

Kilowatt (kW)

Actual Power expressed in Kilo-Watts (KW).

Latent Cooling Capacity

The fraction of total capacity an air conditioner or air handler uses to condense liquid water from the air stream being cooled. Latent cooling capacity does not contribute to data center equipment cooling.

Latent Heat of Evaporation

A term describing the amount of latent heat transferred during a liquid / vapor phase change for a particular substance.

Lead Acid Battery

The assembly of one or more cells with an electrolyte, based on dilute sulfuric acid and water, a positive electrode of lead dioxide and negative electrodes of lead. The positive plate is comprised of lead dioxide and the negative of finely divided lead, both react with the sulfuric acid electrolyte to form lead sulfate on discharge. The reaction is reversed on recharge. Batteries are constructed with lead grids to support the active material and individual cells are connected to produce a battery in a plastic or glass case.

Lightning Arrester

This device provides protection for equipment from high voltage surges caused by lightning. Connected from line to ground potential, the device has a very high resistance to current flow at normal voltages but when a very high voltage surge hits it, it becomes a very low resistance, passing damaging surges and current to ground.

Liquid Line

A refrigerant pipe carrying liquid refrigerant connected the output side of the condensing coil and to the input side of the expansion valve.

Load

The amount of electrical power required by connected electrical equipment. The total impedance of all the items in an output circuit.

Load bank

A device that creates an electrical load. Used for testing of electrical and mechanical systems, typically during commissioning.

Make Up Air

Outside air introduced into the interior. Make-up air is referred to by building codes primarily to ensure the space is fit for human occupancy.

Megawatt (mW)

1,000,000 watts.

MEP

Mechanical, Electrical and Plumbing Systems

Mean Time Between Failures (MTBF )

Is the mean (average) time between failures of a system, and is often attributed to the useful life of the device, not including 'infant mortality' or 'end of life' if the device is not repairable. Calculations of MTBF assume that a system is fixed, after each failure, and then returned to service immediately after failure.

Mean Time To Repair (MTTR)

Is the maximum time to recovery after an equipment failure which can be easily measured and a supplier held accountable.

Manual Transfer Switch (MTS)

A manually actuated switch that transfers electrical loads to an alternate or emergency-standby power source.

NEC

National Electrical Code

NFPA

National Fire Protection Association

Network Operations Center (NOC)

A designated location used for monitoring a network for alarms or certain conditions which may require special attention to avoid impact on the networks performance.

Parallel Generator Systems

A system that is capable of providing large amounts of stand-by power or emergency power by incorporating multiple generators in parallel via a series of switching and controls.

Power Distribution Unit (PDU)

A freestanding, data center floor serving, electrical device usually composed of a transformer and electrical panels used to supply power to an immediate area. Also small well-constructed power strips suitable for datacenter use are referred to as PDUs.

Plenum

Any dedicated space that is used for the distribution or return of cooling air. The space under a raised floor is an example of a plenum.

Power Density

Electrical power used in a space divided by the area of the space.

Power Factor

The ratio of energy consumed (watts) versus the product of input voltage (volts) times input current (amps). In other words, power factor is the percentage of energy used compared to the energy flowing through the wires.

Pre-Action Fire Sprinkler

A fire sprinkler system that employs the basic concept of a dry pipe system in that water is not normally contained within the pipes. Water is held from piping by an electrically operated valve, known as a pre-action valve. Valve operation is controlled by independent flame, heat, or smoke detection. Two separate events must are required to initiate sprinkler discharge. First, the detection system must identify a developing fire and then open the pre-action valve. This allows water to flow into system piping, which effectively creates a wet pipe sprinkler system. Second, individual sprinkler heads must release to permit water flow onto the fire.

Precision Air Conditioning

A term describing air conditioning or air handling systems specifically designed to cool information technology equipment in a data center or server room. Precision air conditioning systems typically maintain temperature (+/- 1F) and humidity (+/-4%). These systems provide high airflow rates (170+ CFM/kW or 4.8+ Lps/kW), are designed for continuous 24/7/365 usage, and provide high levels of air filtration.

Pump Package

A pump or pumps and enclosure or skid used in coordination with a cooling system to circulate condenser water or glycol on applicable systems.

Raised Floor

A system of pedestals, stringers, and floor tiles, that create an elevated floor environment. The under floor is accessible and can be used as a distribution path for air conditioning, HVAC piping, data and electrical systems.

Redundancy

A backup system or component

Refrigerant

The working fluid used in the refrigeration cycle is known as the refrigerant. Modern systems primarily use fluorinated hydrocarbons that are nonflammable, non-corrosive, nontoxic, and non-explosive. Refrigerants are commonly referred to by their ASHRAE numerical designation. The most commonly used refrigerant in the IT environment is R-22. Environmental concerns of ozone depletion may lead to legislation increasing or requiring the use of alternate refrigerants like R-134a.

Refrigeration Cycle

Refrigerant changes its physical state from liquid to gas and back to liquid again each time it traverses the various cooling system components. As the refrigerant changes state from liquid to gas, heat energy flows into the refrigerant from area to be cooled. Conversely, as the refrigerant changes state from gas to liquid heat energy flows away from the refrigerant to a different environment.

Relative Humidity

The amount of water vapor contained in air relative to the maximum amount the air is capable of holding. Expressed in %.

Reliability

Reliability is classically defined as the probability that some item will perform satisfactorily for a specified period of time under a stated set of conditions.

Return Air

Air entering an air conditioning system that I used to move heat energy to the evaporator coil.

Sensible Cooling Capacity

The amount of heat energy the air conditioner can be expected to remove from an environment with computer or server equipment. Depending on the operating conditions, this may be less than the air conditioner rating because some of the air conditioner cooling capacity may be used up dehumidifying the air. The resultant condensation of the humidity onto the air conditioner coils represents a loss of cooling capacity. Ideally, the air returning to the air conditioner is a high enough temperature so that the dew point is not reached during cooling, in which case no dehumidification occurs and the full air conditioner rating is used to cool the heat load.

Sensible Heat

Sensible heat is defined as the heat energy that causes a change in temperature of a substance but does not contribute to a change in state (for example, steam to liquid water) for the substance. The only type of heat energy produced by computers and IT type equipment.

Sensible Heat Ratio

The ratio between an air conditioner's sensible heat removal capacity and its total heat removal capacity. In an data center environment, higher sensible heat ratios contribute to lower operating costs and more effective equipment cooling. Ideally, this ratio is 1, meaning the entire air conditioner capacity is available to cool the load. When this number is less than 1, it means that undesirable dehumidification is occurring in the air conditioner.

Server Room

A location specifically designed to house a high concentration of information technology equipment.

Single Phase (electricity)

Single Phase electric power refers to the distribution of electric power using a system in which a single leg or phase is taken from a three Phase source either by connection between a phase and neutral or by connecting the load between two phases.

SOW

Statement Of Work.

Spike

A sudden marked jump in voltage, which can damage electronics and corrupt or destroy data.

Spike/Surge Protector

An appliance designed to protect electrical devices from voltage spikes. Surge protectors attempt to regulate the voltage supplied to an electric device by either blocking or by shorting to ground voltages above a safe threshold.

Standby Generator

The generator is the main component in a back-up electrical system that operates automatically. Within seconds of a utility outage an automatic transfer switch senses the power loss, commands the generator to start and then transfers the electrical load to the generator. The standby generator begins supplying power to the power distribution system. After utility power returns, the automatic transfer switch transfers the electrical load back to the utility and signals the standby generator to shut off. It then returns to standby mode where it awaits the next outage. To ensure a proper response to an outage, a standby generator runs weekly self-tests. Most units run on diesel, natural gas .

Static Transfer Switch (STS)

A static transfer switch selects between two or more sources of power and provides the best available power to the critical load.

Supply Air

Air entering a space from an air conditioner

Surge

A surge is a prolonged over-voltage condition. Surges can damage electronics and corrupt or destroy data.

Switchgear

A general term covering switching and interrupting devices and their combination with associated control, metering, protective and regulating devices. Also, the assemblies of these devices with associated interconnection, accessories, enclosures and supporting structure, used primarily in connection with the generation, transmission, distribution and conversion of electric power.

T&C

Terms and Conditions.

TBD

To Be Determined.

Three Phase (electricity)

Three-phase refers to an electric power system having at least three conductors carrying voltage waveforms that are 2ð/3 radians (120°,1/3 of a cycle) offset in time. Electric utilities generate three phase power and transmit it to load centers where it may be consumed at Three Phase or Single Phase.

Ton (Cooling)

A ton is heat energy equal to 12,000 BTUs and is the amount of heat energy required to melt 2000 pounds (907kg) of ice in one hour. This is an archaic term typically used to specify heat output when expressed in Tons/day, where the use of the more modern term Watts is the simpler and more universal measure that should be used.

Transformer

An electro-magnetic device used to change the voltage in an alternating current electrical circuit.

Transient Voltage Surge Suppressor (TVSS)

A device used to reduce voltage surges. Products may be wired in series or in parallel with the AC electrical conductors.

Turning Vane

An air management device installed in many floor stands to assist in redirecting the flow of cooling air from vertical to horizontal as it exits the computer room air conditioner or air handler.

UL

Underwriters Laboratories, Inc

Uninterruptible Cooling

The process of continued heat removal from the IT room or data center during equipment failure or power failure to preclude thermal damage and data loss due to equipment overheating.

Uninterruptible Power Supply (UPS )

A device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not available. There are two distinct types of UPS: off-line and line-interactive (also called on-line). An off-line UPS remains idle until a power failure occurs, and then switches from utility power to its own power source, almost instantaneously. An on-line UPS continuously powers the protected load from its reserves (usually lead-acid batteries or stored kinetic energy), while simultaneously replenishing the reserves from the AC power. The on-line type of UPS, in addition to providing protection against complete failure of the utility supply, provides protection against all common power problems, and for this reason it is also known as a power conditioner and a line conditioner.

Up Flow

A term applied to air conditioners and air handlers that discharge air in an upward direction.

Utility Power

Power from the local utility company

VA

Volt Amps.

Valve Regulated Sealed Cell (Battery)

A battery in which the cells are closed but have a valve which allows the escape of gas if the internal pressure exceeds a predetermined value.

Vapor Barrier

Paint, plastic sheeting, floor or ceiling material specifically designed to minimize the migration of humidity into or out of an area.

Venting (Battery)

The controlled or accidental release of gas from a battery cell.

Virtualization

Virtualization is a framework or methodology of dividing the resources of a computer into multiple execution environments, by applying one or more concepts or technologies such as hardware and software partitioning, time-sharing, partial or complete machine simulation, emulation, quality of service, and many others.

Voltage

Electrical force or potential, a technical synonym for voltage is emf or "electromotive force." Voltage is the parameter of electricity which causes current to flow when a circuit is completed. Voltage is always presented in an energized line, whether or not the circuit is complete.

Voltage Regulator

A device designed to regulate RMS voltage by removing swells and sags.

Water Cooled System

A water-cooled system uses water instead of air as a condensing medium. Condensation takes place in a refrigerant/water heat exchanger typically located within the air conditioner. The water flows in a continuous loop to an outdoor cooling tower where heat is rejected to the outside atmosphere.

Water Detector

A device used to sense the abnormal presence of liquid water due to a leak or condensation.

Watt

A derived unit of power, equal to one joule of energy per second, a measurement of energy commonly used to measure electrical and heat loads.