Power Infrastructure
48V DC Distribution
48-volt DC distribution delivers direct current at 48 volts from a central rectifier or power shelf to servers,…
Power Infrastructure
A-Side and B-Side Power
A-Side and B-Side Power refers to two independent, redundant power distribution paths (A and B) feeding the same…
Power Infrastructure
Active Harmonic Filter
An active harmonic filter is a power-electronic device that measures load current harmonics and injects an equal, opposite…
Power Infrastructure
Air Circuit Breaker
An Air Circuit Breaker (ACB) is a low-voltage breaker that interrupts high currents in air, using arc chutes…
Power Infrastructure
Arc-Resistant Switchgear
Arc-resistant switchgear is switchgear built and tested so that an internal arcing fault is contained and its hot…
Power Infrastructure
Automatic Transfer Scheme
An Automatic Transfer Scheme is a control arrangement that detects loss of a primary utility or power source…
Power Infrastructure
Automatic Transfer Switch
An Automatic Transfer Switch (ATS) is a device that senses loss of the normal power source and automatically…
Power Infrastructure
Automatic Voltage Regulator
An Automatic Voltage Regulator (AVR) is the control device on a generator that adjusts the field excitation current…
Power Infrastructure
Autonomy Time
Autonomy Time is how long a UPS can supply the connected load solely from its stored energy after…
Power Infrastructure
Battery Cabinet
A Battery Cabinet is an enclosure housing the battery strings that supply stored energy to a UPS during…
Power Infrastructure
Battery Energy Storage System
A Battery Energy Storage System (BESS) is an integrated installation of battery racks, inverters, controls, and thermal management…
Power Infrastructure
Battery Monitoring System
A Battery Monitoring System (BMS) continuously measures parameters such as cell voltage, internal resistance, current and temperature to…
Power Infrastructure
Behind-the-Meter Generation
Behind-the-meter generation is electricity produced on the customer side of the utility revenue meter, such as on-site solar,…
Power Infrastructure
Black Start
Black Start is the capability to restore a facility's power from a fully de-energized state using on-site generation,…
Power Infrastructure
Block Load
A block load is a large step increase in electrical demand applied to a generator in a single…
Power Infrastructure
Branch Circuit Monitoring
Branch Circuit Monitoring (BCM) is the measurement of electrical parameters on individual branch circuits, typically at the PDU…
Power Infrastructure
Breaker Coordination
Breaker Coordination is the setting of circuit breakers' trip characteristics so that the breaker closest to a fault…
Power Infrastructure
Bulk Fuel Tank
A Bulk Fuel Tank is a large storage tank holding the site's main reserve of generator fuel, from…
Power Infrastructure
Bus Tie Breaker
A bus tie breaker is a circuit breaker that connects two sections of a switchboard or two independent…
Power Infrastructure
Busbar Trunking
Busbar Trunking is a modular power distribution system of enclosed busbars supplied in standard lengths with pluggable tap-off…
Power Infrastructure
Busway
A Busway is a prefabricated power distribution system using enclosed metal conductors (busbars) in a rigid housing, with…
Power Infrastructure
Bypass Mode
Bypass Mode is an operating state in which the UPS routes the load directly from the utility or…
Power Infrastructure
C-Rate
C-rate is the measure of how fast a battery is charged or discharged relative to its capacity, where…
Power Infrastructure
Critical Load
Critical Load is the portion of a data center's electrical demand that directly powers IT equipment and the…
Power Infrastructure
Curtailment
Curtailment is the reduction of a facility's grid power draw or a generator's output in response to a…
Power Infrastructure
Day Tank
A Day Tank is a small fuel tank mounted at or near a generator that holds a ready…
Power Infrastructure
Delta-Conversion UPS
A delta-conversion UPS is a double-conversion alternative in which a delta converter handles only the difference between input…
Power Infrastructure
Demand Response
Demand Response is a program in which a facility adjusts its grid power draw, by shedding load or…
Power Infrastructure
Depth of Discharge
Depth of Discharge (DoD) is the fraction of a battery's total capacity that has been withdrawn during a…
Power Infrastructure
Diesel Exhaust Fluid
Diesel Exhaust Fluid (DEF) is a metered solution of urea and deionized water injected into the exhaust of…
Power Infrastructure
Diesel Generator
A Diesel Generator is a generator set driven by a diesel engine, the traditional workhorse for data-center standby…
Power Infrastructure
Diesel Rotary UPS
A Diesel Rotary UPS (DRUPS) is an uninterruptible power supply that stores energy kinetically in a spinning flywheel…
Power Infrastructure
Double-Conversion UPS
A Double-Conversion UPS continuously rectifies incoming AC to DC and then inverts it back to clean AC, so…
Power Infrastructure
Dry-Type Transformer
A dry-type transformer uses air and solid insulation, often cast-resin encapsulated windings, instead of insulating oil, eliminating the…
Power Infrastructure
Eco-Mode UPS
Eco mode is a UPS operating mode in which the load is normally fed through a high-efficiency bypass…
Power Infrastructure
Emissions Permit
An Emissions Permit is a regulatory authorization defining the air pollutants a facility may release and under what…
Power Infrastructure
Energy Storage System
An Energy Storage System (ESS) captures electrical energy for later use, typically in batteries, to provide backup, ride-through,…
Power Infrastructure
Engine Governor
An engine governor is the control that regulates fuel delivery to hold a generator's engine speed, and therefore…
Power Infrastructure
Exhaust Stack
An Exhaust Stack is the vertical duct that discharges a generator engine's exhaust gases to atmosphere at a…
Power Infrastructure
Fault Current
Fault Current is the large current that flows during an electrical fault such as a short circuit, far…
Power Infrastructure
Flywheel UPS
A Flywheel UPS stores kinetic energy in a high-speed rotating mass and converts it back to electrical power…
Power Infrastructure
Frequency Regulation
Frequency regulation is the continuous balancing of generation and load to hold grid frequency near its nominal value…
Power Infrastructure
Fuel Autonomy
Fuel Autonomy is the length of time a site's generators can run on stored fuel before resupply is…
Power Infrastructure
Fuel Cell
A fuel cell is an electrochemical device that converts the chemical energy of a fuel, typically hydrogen or…
Power Infrastructure
Fuel Polishing
Fuel Polishing is the process of filtering and cleaning stored diesel to remove water, sediment and microbial contamination…
Power Infrastructure
Gas Generator
A Gas Generator is a generator set fueled by natural gas or another gaseous fuel rather than diesel.…
Power Infrastructure
Generator Acoustic Enclosure
A generator acoustic enclosure is a weatherproof, sound-attenuating housing around an engine-generator set, lined with absorptive material and…
Power Infrastructure
Generator Paralleling Gear
Generator Paralleling Gear is the switchgear and controls that synchronize multiple generator sets and connect them to a…
Power Infrastructure
Generator Run Test
A Generator Run Test is a scheduled exercise in which standby generators are started and run, often under…
Power Infrastructure
Grid Interconnection Study
A Grid Interconnection Study is a utility analysis of the impact of connecting a new large load to…
Power Infrastructure
Grid-Forming Inverter
A grid-forming inverter is a power converter that actively establishes voltage and frequency for a network rather than…
Power Infrastructure
Grid-Interactive UPS
A grid-interactive UPS is an uninterruptible power supply whose inverter can export power or ancillary services to the…
Power Infrastructure
Grid-to-Chip
Grid-to-Chip is a design and planning philosophy that treats the entire electrical path — from the utility grid…
Power Infrastructure
Harmonic Distortion
Harmonic Distortion is the deviation of voltage or current waveforms from a pure sine wave caused by non-linear…
Power Infrastructure
High Voltage Interconnection
A High Voltage Interconnection is the connection of a site to the transmission grid at high voltage, typically…
Power Infrastructure
HVO Fuel
HVO (Hydrotreated Vegetable Oil) is a paraffinic renewable diesel made by hydrogenating fats and vegetable oils, producing a…
Power Infrastructure
Inrush Current
Inrush current is the brief, high surge of current drawn when equipment is first energized, most notably the…
Power Infrastructure
Intelligent PDU
An Intelligent PDU is a rack PDU with networked monitoring and control, reporting power, voltage, current and often…
Power Infrastructure
Islanding
Islanding is the condition in which a portion of the electrical network continues to be energized by local…
Power Infrastructure
Isolated-Parallel Bus
An Isolated-Parallel (IP) bus is a UPS system architecture in which each UPS module feeds its own load…
Power Infrastructure
Line-Interactive UPS
A Line-Interactive UPS feeds the load from conditioned utility power while using an inverter and often an autotransformer…
Power Infrastructure
Lithium Iron Phosphate Battery
A Lithium Iron Phosphate (LFP) battery is a lithium-ion variant using an iron-phosphate cathode that trades some energy…
Power Infrastructure
Lithium-Ion Battery
A Lithium-Ion Battery stores energy electrochemically using lithium-based chemistries and, in data centers, is increasingly used for UPS…
Power Infrastructure
Load Bank Connection
A Load Bank Connection is a permanent or temporary connection point that lets a portable or fixed load…
Power Infrastructure
Load Shedding
Load shedding is the deliberate disconnection of selected electrical loads to keep the remaining system within the capacity…
Power Infrastructure
Main Substation
A Main Substation is the primary on-site or dedicated facility that receives incoming utility power, transforms it to…
Power Infrastructure
Medium Voltage Service
Medium Voltage Service is utility supply delivered at medium voltage, broadly ranging from about 1 kV up to…
Power Infrastructure
Modular UPS
A Modular UPS is built from multiple hot-swappable power modules within a common frame, allowing capacity and redundancy…
Power Infrastructure
Molded Case Circuit Breaker
A Molded Case Circuit Breaker (MCCB) is a low-voltage breaker housed in an insulating molded case, providing overload…
Power Infrastructure
Motor Control Center
A Motor Control Center (MCC) is a floor-standing assembly of enclosed sections housing motor starters, drives, protection, and…
Power Infrastructure
N+1 Generator Plant
An N+1 Generator Plant is a standby generation system that includes one more generator than the number strictly…
Power Infrastructure
Nickel-Zinc Battery
A nickel-zinc battery is a rechargeable cell using a nickel oxide-hydroxide cathode and a zinc anode in an…
Power Infrastructure
On-Load Tap Changer
An On-Load Tap Changer (OLTC) is a transformer mechanism that switches between winding taps to adjust the turns…
Power Infrastructure
Panelboard
A Panelboard is a wall-mounted electrical distribution assembly that divides an incoming feed into multiple branch circuits, each…
Power Infrastructure
Point of Common Coupling
The Point of Common Coupling (PCC) is the electrical node where a facility's private power system connects to…
Power Infrastructure
Power Distribution Unit
A Power Distribution Unit (PDU) is equipment that takes an incoming feed and distributes conditioned power to multiple…
Power Infrastructure
Power Factor Correction
Power factor correction is the addition of capacitors or active devices to supply the reactive power that inductive…
Power Infrastructure
Power Quality
Power Quality describes how closely supplied voltage and current match ideal characteristics of stable magnitude, frequency and clean…
Power Infrastructure
Power Shelf
A power shelf is a rack-mounted assembly of hot-swappable rectifier or power-supply modules that converts incoming AC to…
Power Infrastructure
Prime Power Rating
A prime power rating defines the output a generator set can supply for unlimited hours serving a variable…
Power Infrastructure
Rack PDU
A Rack PDU is a power strip mounted within or on a server rack that distributes power to…
Power Infrastructure
Reactive Power
Reactive power is the component of AC power, measured in volt-amperes reactive (VAR), that oscillates between source and…
Power Infrastructure
Remote Power Panel
A Remote Power Panel (RPP) is a distribution panel placed within the data hall, close to the racks,…
Power Infrastructure
Remote Radiator
A remote radiator is an engine cooling arrangement in which the heat-rejection radiator is located away from the…
Power Infrastructure
Ride-Through Time
Ride-Through Time is the duration a power system can maintain the critical load from stored energy during a…
Power Infrastructure
Ring Main Unit
A Ring Main Unit (RMU) is a compact medium-voltage switchgear assembly used to connect a site into a…
Power Infrastructure
Round-Trip Efficiency
Round-trip efficiency is the ratio of energy retrieved from a storage system to the energy put into it…
Power Infrastructure
Selective Catalytic Reduction
Selective Catalytic Reduction (SCR) is an exhaust after-treatment system that injects a reagent, typically urea-based, into a catalyst…
Power Infrastructure
Selective Coordination
Selective Coordination is the design of protective devices so that only the device nearest a fault operates, isolating…
Power Infrastructure
Short-Circuit Rating
A Short-Circuit Rating is the maximum fault current that a device or assembly, such as switchgear, a breaker…
Power Infrastructure
Small Modular Reactor
A Small Modular Reactor (SMR) is a factory-built nuclear reactor of roughly 10 to 300 megawatts electrical, delivered…
Power Infrastructure
Solid-State Transformer
A Solid-State Transformer (SST) is a power-electronic device that performs voltage conversion using high-frequency switching and a small…
Power Infrastructure
Standby Generator
A Standby Generator is an engine-driven generator set that starts on loss of utility power to supply the…
Power Infrastructure
State of Charge
State of Charge (SOC) is the remaining capacity of a battery expressed as a percentage of its full…
Power Infrastructure
Static Bypass Switch
A Static Bypass Switch is the fast solid-state switch within a UPS that transfers the load between the…
Power Infrastructure
Static Transfer Switch
A Static Transfer Switch (STS) is a solid-state device that automatically transfers a load between two independent power…
Power Infrastructure
Static UPS
A Static UPS uses solid-state power electronics, rectifiers, inverters and static switches, together with a battery or capacitor…
Power Infrastructure
Step-Down Transformer
A Step-Down Transformer reduces voltage from a higher supply level to a lower one, for example from medium…
Power Infrastructure
Supercapacitor Energy Storage
Supercapacitor energy storage uses electrochemical double-layer capacitors that store energy electrostatically, delivering very high power in short bursts…
Power Infrastructure
Switchboard
A Switchboard is a floor- or wall-mounted assembly that receives power from a source and distributes it to…
Power Infrastructure
Switched Rack PDU
A switched rack PDU is an intelligent rack power distribution unit whose individual outlets can be turned on…
Power Infrastructure
Switchgear
Switchgear is the assembly of switches, circuit breakers, protective relays, busbars and metering used to control, protect and…
Power Infrastructure
UPS
A UPS (Uninterruptible Power Supply) provides near-instantaneous backup power to critical loads during utility disturbances or outages, bridging…
Power Infrastructure
Utility Metering
Utility Metering is the measurement of electrical energy and demand imported from (or exported to) the grid at…
Power Infrastructure
Utility Service Entrance
The Utility Service Entrance is the point where the utility's conductors enter the site or building and connect…
Power Infrastructure
Vacuum Circuit Breaker
A Vacuum Circuit Breaker (VCB) interrupts current by drawing the arc apart inside a sealed vacuum interrupter, where…
Power Infrastructure
Virtual Power Plant
A Virtual Power Plant (VPP) is a cloud-coordinated aggregation of distributed energy resources such as batteries, generators, and…
Power Infrastructure
VRLA Battery
A VRLA (Valve-Regulated Lead-Acid) Battery is a sealed, maintenance-light lead-acid battery long used for UPS energy storage. Its…
Power Infrastructure
Wet Stacking
Wet stacking is the accumulation of unburned fuel, soot, and condensed water in the exhaust system of a…
Power Infrastructure
Whip
A Whip is a flexible, pre-terminated power cable, usually with a plug or connector, that runs from a…