Power Glossary
A
Aeroderivative (AERO)
Smaller and lighter than industrial gas turbines, these engines leverages advanced engineering and specialized metallurgy from the aviation industry.
Alberta Electric System Operator (AESO)
An Independent System Operator (ISO) responsible for managing the power grid and wholesale electricity market in the Canadian province of Alberta.
Amp
The unit of measurement for the flow, or current, of electricity through a conductor. One amp equals 0.001 kilowatts per hour (kWh).
Ancillary services
Essential functions that keep the grid running reliably and securely by maintaining frequency, voltage, and power load within certain limits. These services are procured from market participants to manage real-time fluctuations in supply and demand, as well as unexpected outages.
B
Base load
A facility with near-constant operation delivering electricity to the grid to meet steady, round-the-clock demand. Unlike peak load plants, baseload plants run night and day, using nuclear, natural gas, coal, or geothermal resources.
Blackout
A complete loss of electrical power affecting a broad area, typically unplanned and caused by severe weather or equipment failure.
Blade
An airfoil-shaped component in a gas turbine engine. The blades convert the kinetic and thermal energy of gas into mechanical, rotational energy to drive a shaft and, in turn, power a generator or the engine’s compressor.
Borescope inspection (BSI)
A nondestructive technique using a camera to see inside an engine without disassembling it. Done in the field or at a depot, a BSI enables detecting wear, cracks, pitting, corrosion, debris, or other conditions.
Brownout
A partial reduction in electrical power in a particular area, often planned by utilities to prevent grid overload.
C
Calibration (CAL)
The process of comparing and adjusting the accuracy of an instrument to ensure its readings match a known standard.
Capability
The maximum load that an electrical apparatus can carry under specified conditions for a given period of time, without exceeding approved limits of temperature and stress.
Capacity
The load for which an electrical apparatus is rated, usually stated by manufacturer’s nameplate ratings.
Combined heat and power (CHP)
The sequential generation of electricity and useful heat from the same fuel. Also known as cogeneration.
Combustion
A rapid chemical reaction between a fuel, like natural gas, and oxygen that releases significant heat, which drives aeroderivative engines to generate electricity.
Combustor (COMB)
A chamber in a gas turbine where compressed air mixes with fuel and ignites, which creates hot, high-pressure gas that spins the turbine to produce power.
Compressor
A basic component of a gas turbine that squeezes incoming air into a smaller volume, which increases the air pressure and temperature to enable combustion.
Compressor rear frame (CRF)
A structural section at the back of the compressor that supports internal components and helps to guide airflow toward the next stage of the system.
Consumption
The total energy used over time. Consumption is measured in kilowatt-hours (kWh). Compare with demand.
D
Demand
The rate at which electric energy is used at a specific time. Demand is measured in kilowatts (kW). Compare with consumption.
Direct energy deposit (DED)
An advanced manufacturing technique used to build or repair parts in layers by melting material with a focused energy source and creating one solid piece.
Dispatchable
Resources, like power plants or storage, that grid operators can turn off and on to quickly and reliably match electricity demand.
Distributed control system (DCS)
A computerized system that monitors and controls processes across multiple locations.
Dry low emissions (DLE)
A technology that reduces pollutants, especially nitrogen oxides (NOx), from gas-fired turbines.
E
Efficiency
A measure comparing the total energy input with output.
Electric Reliability Council of Texas (ERCOT)
An Independent System Operator (ISO) responsible for managing the power grid and wholesale electricity market in most of Texas. ERCOT is regulated by the Public Utility Commission of Texas (PUCT) rather than the Federal Energy Regulatory Commission (FERC) like other major ISOs such as in California.
Engineering, procurement, and construction (EPC)
A project delivery method where one contractor handles a large-scale project from start to finish. EPC includes the stages for designing a power plant, buying all equipment and materials, and building the power plant.
Environmental Protection Agency (EPA)
An independent executive agency of the US federal government tasked with protecting people and the environment from significant health risks, as well as sponsoring and conducting research.
Environmental, social, and governance (ESG)
A framework used to track progress on sustainability in the context of business and investment.
Exhaust
A system in a gas turbine that collects extremely hot, high-velocity gases and directs them for release into the atmosphere.
F
Federal Energy Regulatory Commission (FERC)
An independent federal agency that regulates wholesale electricity markets and interstate transmission by establishing rules and providing oversight. FERC oversees Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs). FERC also directs the North American Electric Reliability Corporation (NERC).
Flow & instrumentation diagram (F&ID)
A detailed schematic, primarily used in engineering, showing the pipes and related components in a process flow.
G
Generation
The process of transforming various energy sources into electricity.
Generator
A machine that converts a rotational mechanical energy into electrical energy.
Generator step-up unit (GSU)
A large power transformer that increases voltage output from power generators to higher levels for efficient, long-distance transmission across the power grid.
Gigawatt (GW)
A unit of power for measuring the rate at which energy is used or generated. One gigawatt (GW) is equal to one billion watts.
Grid
A vast, interconnected network for the delivery of electricity from producers to consumers.
H
Heat rate (HR)
A measure of thermal efficiency. Generally expressed in Btu per kilowatt-hour, it indicates how much fuel energy (Btu) is needed to produce one unit of electrical energy (kilowatt-hour).
High-pressure compressor (HPC)
One of four major rotating sections in an aeroderivative engine, the HPC handles the significant pressure increase for the high-pressure turbine (HPT) on the inner shaft. The other three sections include the low-pressure compressor (LPC), low-pressure turbine (LPT), and HPT.
High-pressure section (HP)
The portion of the gas turbine centered around the high-pressure turbine (HPT) and connected to the high-pressure compressor (HPC), which handles the highest temperatures and pressures after combustion.
High-pressure turbine (HPT)
One of four major rotating sections in an aeroderivative engine, the HPT handles the hottest, highest pressure gas after the combustor, driving the high-pressure compressor (HPC). The other three sections include the low-pressure compressor (LPC), low-pressure turbine (LPT), and HPC.
Hot section exchange (HSE)
A maintenance procedure in which worn or damaged high-temperature components are switched with reconditioned ones to restore an aeroderivative engine to service with minimal downtime and reduced costs.
Hot section repair (HSR)
The maintenance, inspection, and refurbishment of high-temperature components, such as the combustor, blades, vanes, and exhaust, in aeroderivative engines. Specialized repair techniques like welding, coatings, and machining address wear, cracks, and corrosion.
Human-machine interface (HMI)
Hardware or software that enables people to interact with, monitor, and control systems or devices.
I
Ignition
The application of sufficient heat to start combustion of the fuel-air mixture within an engine and produce power.
Independent Electricity System Operator (IESO)
An Independent System Operator (ISO) responsible for managing the power grid and wholesale electricity market in Ontario, Canada.
Independent power producer (IPP)
A private entity that owns and operates power generation facilities and sells electricity wholesale, typically through power purchase agreements (PPAs).
Independent service provider (ISP)
A third-party company that provides operations and maintenance (O&M) services for equipment like aeroderivative engines.
Independent System Operator (ISO)
A nonprofit organization that manages the electrical power grid and the wholesale power market for designated regions. ISOs perform similar roles to Regional Transmission Organizations (RTOs) but these typically cover smaller, single-state areas. In the US, ISOs are regulated by the Federal Energy Regulatory Commission (FERC), with the exception of the Electric Reliability Council of Texas (ERCOT).
Independent System Operator-New England (ISO-NE)
An Independent System Operator (ISO) responsible for managing the power grid and wholesale electricity market in six New England states, including Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont.
Instrumentation & controls (I&C)
A system that controls power plant processes for safe, reliable power generation.
Integrated Resource Plan (IRP)
A long-term, comprehensive roadmap used by utilities to meet forecasted electricity demand over a specified period reliably, affordably, and sustainably.
Intermittent
Energy production that varies over time because of factors such as weather conditions.
J
K
Kilowatt (kW)
A unit of electrical power for measuring the rate at which energy is used or generated. One kilowatt (kW) is equal to 1,000 watts.
Kilowatt-hour (kWh)
A unit measuring electrical energy, which represents the amount of power (1,000 watts) used or generated over one hour.
L
Limited notice to proceed (LNTP)
Authorization for a contractor to begin pre-construction activities on a project before full funding or approval to prevent delays and reduce risks.
Low-pressure compressor (LPC)
One of four major rotating sections in an aeroderivative engine, the LPC provides initial, large-volume compression, driven by the low-pressure turbine (LPT) on the outer shaft. The other three sections include the LPT, high-pressure compressor (HPC), and high-pressure turbine (HPT).
Low-pressure turbine (LPT)
One of four major rotating sections in an aeroderivative engine, the LPT takes the cooler, lower pressure exhaust, driving the fan and low-pressure compressor (LPC). The other three sections include the LPC, high-pressure compressor (HPC), and high-pressure turbine (HPT).
M
Main generator terminal box (MGTB)
A protective enclosure that provides a safe exit point for electrical power from a generator.
Main turbine terminal box (MTTB)
An industrial interface connecting turbine sensors and protection devices to the main control system.
Major overhaul (MOH)
A complete inspection, cleaning, repair, and replacement of worn parts in an engine to restore it to serviceable condition so it operates with improved efficiency and extended longevity.
Master service agreement (MSA)
A fundamental contract for all future transactions between two parties that defines general terms and conditions. The MSA is broader and more high level than a total care service agreement (TCSA).
Megawatt (MW)
A unit of power for measuring the rate at which energy is used or generated. One megawatt (MW) is equal to one million watts.
Midcontinent Independent System Operator (MISO)
An Independent System Operator (ISO) responsible for managing the power grid and wholesale electricity market in Manitoba, Canada, and 15 Midwest US states, including Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, North Dakota, South Dakota, Texas, and Wisconsin.
N
Nameplate rating
The maximum continuous output or capacity of electrical equipment (like an engine or generator) under ideal conditions, as specified by the manufacturer and found on a physical tag (or nameplate).
New York Independent System Operator (NYISO)
An Independent System Operator (ISO) responsible for managing the power grid and wholesale electricity market in the state of New York.
Nonconformance report (NCR)
A formal, organized document used in quality management to identify and communicate any deviation between the actual product, service, or process and the defined requirements.
North American Electric Reliability Corporation (NERC)
A nonprofit international regulatory authority responsible for areas spanning the continental US, Canada, and parts of Mexico. NERC develops and enforces reliability standards, as well as works with regional entities for compliance.
O
Original equipment manufacturer (OEM)
A company that produces equipment, often with a focus on high-quality, custom-designed components, with the intent to sell them to other companies in business-to-business (B2B) transactions.
P
Peak load
The highest level of electrical demand on a power grid over a specific time.
Pennsylvania-Jersey-Maryland Interconnection (PJM)
A Regional Transmission Organization (RTO) responsible for managing the power grid and wholesale electricity market in all or part of 13 US states, including Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and the District of Columbia.
Piping & instrumentation diagram (P&ID)
A piping and instrumentation diagram, or P&ID, shows the piping and related components in a physical process flow.
Power (electric)
The time rate of generating, transferring, or using electric energy, usually expressed in kilowatts (kW).
Power distribution center (PDC)
A pre-fabricated enclosure that holds electrical equipment, including switchgear, control panels, and backup power systems, and regulates the distribution of power.
Power purchase agreement (PPA)
A long-term electricity supply contract between two parties, typically between an independent power producer (IPP) and a customer.
Pressure control valve (PCV)
A mechanical device used to manage and maintain desired pressure levels within a system by opening or closing in response to pressure changes.
Public Utility Commission of Texas (PUCT)
A state agency responsible for the economic regulation of electric, telecommunication, water, and wastewater utilities. PUTC oversees the Electric Reliability Council of Texas (ERCOT), which runs the electric grid for 90 percent of Texas’ power needs.
Q
R
Regional Transmission Organization (RTO)
A nonprofit organization that manages the electrical power grid and the wholesale power market of a designated region. RTOs perform similar roles to Independent System Operators (ISOs) but typically cover larger, multistate areas. In the US, RTOs are regulated by the Federal Energy Regulatory Commission (FERC).
Remote monitoring and diagnostics (RM&D)
A management system that uses sensors, software, and other technologies to track, analyze, and diagnose an asset from a distance.
Request for proposal (RFP)
A formal document in which an organization solicits detailed bids from potential vendors for a specific project. The RFP typically outlines the scope of work, objectives, requirements, and evaluation criteria for transparent selection.
Root cause analysis (RCA)
A problem-solving method to identify the cause of an issue and suggest specific, lasting solutions.
S
Selective catalytic reduction (SCR)
An emissions control technology that significantly reduces nitrogen oxides (NO2) from exhaust into nitrogen (N2) and water (H2O).
Service bulletin
An official notice from a manufacturer about known issues and repairs for specific aeroderivative engines and components.
Southwest Power Pool (SPP)
A Regional Transmission Organization (RTO) responsible for managing the power grid and wholesale electricity market across all or part of 14 US states, including Kansas, Oklahoma, New Mexico, Texas, Arkansas, Louisiana, Missouri, South Dakota, North Dakota, Montana, Minnesota, Iowa, Wyoming, and Nebraska.
Substantial completion
A milestone in construction projects when a power plant is ready for commercial operations with minor work remaining.
Substation
A facility that receives power from a plant and then uses equipment to switch, change, or regulate voltage for transmission across long distances and final distribution to homes and businesses.
Supervisory Control Data Acquisition (SCADA)
A system of hardware and software that enables organizations to manage, monitor, and control processes by interfacing with plant-floor machines and viewing real-time data.
T
Total care service agreement (TCSA)
A multiyear service contract for the ongoing maintenance of aeroderivative power plant equipment, often with performance guarantees. Also referred to as a long-term service agreement (LTSA). The TCSA is more specific and detailed than a master service agreement (MSA).
Total plant optimization (TPO)
The efficient operation of a plant in terms of key performance indicators, such as energy consumption, production output, waste reduction, and safety.
Transformer
A static electric device, consisting of windings and a steel core, that transfers power from one circuit to another through changing magnetic fields.
Transmission
The bulk transfer of high-voltage electricity from power plants to substations.
Turbine
An engine that transforms air or fluid energy (like gas) into rotational mechanical energy, which can then power a generator to produce electricity.
Turbine rear frame (TRF)
A support structure at the back of the turbine section that holds components in alignment and helps to straighten exhaust flow.
Turnaround time (TAT)
The total duration between the initiation of a request or process to its successful completion or delivery.
Turnkey
A type of contract or project in which an owner works with a single contractor to complete all project stages.
U
Utility
A public organization providing the community with essential services, such as electricity, gas, or water, and subject to governmental regulation.
V
Variable bleed valve (VBV)
A component of a gas turbine that controls airflow by releasing excess air from the low-pressure compressor (LPC) to prevent the engine from stalling, especially at low power or speed conditions.
Variable inlet guide vanes (VIGV)
A component of a gas turbine comprising adjustable blades at the entrance of a compressor. The VIGV control airflow by changing their angle with engine speed and load to direct air to the compressor blades with precision, which prevents instability and boosts efficiency.
Vibration (VIB)
Unwanted oscillatory motion caused by unbalanced parts or other issues in the gas turbine, which reduces efficiency, strains components, causes wear, and can lead to mechanical failures.
Volt
A unit of measurement for voltage, which is the electrical force or pressure pushing electrons through a conductor.
W
Watt
A unit of electrical power to measure energy generation or consumption. One watt is equal to the amount of work performed by a current of one ampere at a voltage of one volt.