Glossary
Look below for some terms to help you understand more about PSE's electric and natural gas systems as well as our ongoing and upcoming infrastructure improvement projects.
- Advanced Distribution Management System (ADMS)
- Battery Energy Storage System (BESS)
- Biofuel
- Capacity
- Circuit
- Co-location
- Conservation
- Conservation Voltage Reduction
- Decarbonization
- Demand (and peak demand)
- Demand response programs
- Demand-side management (DSM)
- Dispatchable Energy Supply
- Distributed energy resources (DER)
- Distribution automation (DA)
- Distribution line
- District regulator
- Double-circuited
- Easement
- Electric grid
- Energy efficiency
- Energy storage
- FERC
- Fiber optic line
- Gate and limit stations
- Generation
- Grid modernization
- Horizontal directional drill (HDD)
- Hydrogen (H2)
- Intermittent generation
- Liquefied natural gas (LNG)
- Load
- Loop
- Main (as in natural gas main)
- Maintenance
- Microgrids
- Natural gas
- Natural gas system and components
- NERC
- Operational flexibility
- Overhead wires
- Overload
- Planned power outage
- Planning guidelines
- Radial line
- Recloser
- Recompression
- Reliability
- Renewable energy resources (also known as renewables)
- Renewable natural gas (RNG)
- Resiliency
- Right-of-way (ROW)
- SCADA
- Service line
- Single-circuited
- Siting
- Smart Street Lights
- Submarine cable
- Substation
- Switching station
- Targeted electrification
- Town border station
- Transformer
- Transmission automation (TA)
- Transmission line
- Tree wire
- Undergrounding
- Vegetation management
- Volts and kilovolts
- Watt (MW) and Megawatt hour (MWh)
ADVANCED DISTRIBUTION MANAGEMENT SYSTEM (ADMS)
ADMS is a computerized platform PSE can use to monitor and control our distribution system in real time. With more and more technology (like batteries and EVs) connected to our grid, and increases in extreme weather events, ADMS will help keep our energy system running safely and reliably.
BATTERY ENERGY STORAGE SYSTEMS (BESS)
Batteries capture and store energy for later use – like home batteries that provide backup power or utility-scale systems that maintain electricity balance on our grid. Because batteries can store energy from renewables, like wind and solar, they play an important role in PSE’s clean energy implementation plans. Learn more at PSE | Battery Storage.
BIOFUEL
Biofuel is a form of renewable energy made from living matter – like plants, fats, food waste, or manure. It’s just one of many alternative fuels PSE is exploring to reduce carbon emissions and help meet our state’s climate change legislations goals.
CAPACITY
Capacity is an energy resource’s maximum output at “full blast.” For instance, home generators and power plants can only provide so much energy at once. Power lines and other utility equipment have capacity ratings, too, for the maximum amount of electricity they can safely handle at any given moment. To ensure we have enough generation capacity to meet our customers’ growing and changing energy needs, PSE plans years in advance through our IRP process. Learn more at PSE | Integrated Resource Plan.
CIRCUIT
Circuits are paths that carry electricity, and individual circuits are what comprise PSE’s entire electric system. Each one “loops” electricity from a substation to customers’ homes and businesses, and then back to the substation. In more rural areas, a single circuit can stretch over several miles.
CO-LOCATION
Co-locating places new electrical infrastructure or equipment in the same location as existing elements – like utilizing existing poles or transmission corridors. This can speed up project timelines and reduce construction impact on communities. Co-locating isn’t always feasible, but PSE considers it whenever possible.
CONSERVATION
Conservation measures improve the efficiency of the electric grid and reduce PSE’s and our customers’ carbon footprints. PSE offers both residential and business customers a variety of programs and incentives to use less energy – while comfortably managing their energy costs and accommodating their unique energy needs.
CONSERVATION VOLTAGE REDUCTION (CVR)
Conservation Voltage Reduction (CVR) devices fine-tune the voltage on our power lines without impacting customers’ electric service. This helps PSE systems operate more efficiently, which also reduces our overall carbon footprint.
DECARBONIZATION
Decarbonization is the process of reducing or eliminating carbon dioxide emissions from the production or use of energy. PSE is committed to reducing emissions from electric and gas operations and electric supply to net zero by 2030. By 2045, PSE will have a 100% carbon-free electric supply. Learn more at PSE | TOGETHER | Our Clean Energy Commitment.
DEMAND (AND PEAK DEMAND)
Demand is the amount of power used by customers at any point in time. Peak demands are when energy needs are at their highest, like hot summer days or cold winter mornings when customers use lots of energy to heat or cool their homes and businesses.
DEMAND RESPONSE PROGRAMS
Demand response (DR) programs help customers and PSE decrease demand on the electric grid during times of peak use. For instance, customers might voluntarily reduce their energy use for a few hours by allowing PSE to remotely control their thermostats or water heaters. Learn more at PSE | Demand Response Program.
DEMAND-SIDE MANAGEMENT (DSM)
DSM measures (such as energy efficiency and demand response) are part of PSE’s systemwide strategy to incorporate year-round conservation into its grid operations. Efforts like these help lower energy costs for customers, decrease our collective carbon footprints, and in some instances, help offset the need to build new infrastructure.
DISPATCHABLE ENERGY SUPPLY
Dispatchable energy is a power supply that’s available whenever we need it. For PSE, this could be stand-by energy stored in batteries, or fuel reserves like liquid natural gas (LNG) or hydrogen. Dispatchables are especially useful when renewable resources, like wind and solar, can’t generate enough supply to meet demand.
DISTRIBUTED ENERGY RESOURCES (DER)
DERs are flexible energy resources that are typically sited close to customers – in their neighborhoods or at individual homes and businesses. Besides serving customers’ energy needs, they also can be used to provide extra grid capacity or help balance supply and demand. DER examples include battery systems and solar panels, as well as energy efficiency tools, like smart thermostats and smart water heaters. DISTRIBUTION AUTOMATION (DA) Distribution Automation (DA) uses devices called reclosers to sense where outages are happening on our power lines. Reclosers can pinpoint a line issue, isolate it, and minimize impacts on the surrounding system. Sometimes, DA can automatically reenergize line interruptions without needing a service crew. This means fewer and shorter outages, which improves the reliability of customers’ electric service.
DISTRIBUTION AUTOMATION (DA)
Distribution Automation (DA) uses devices called reclosers to sense where outages are happening on our power lines. Reclosers can pinpoint a line issue, isolate it, and minimize impacts on the surrounding system. Sometimes, DA can automatically reenergize line interruptions without needing a service crew. This means fewer and shorter outages, which improves the reliability of customers’ electric service.
DISTRIBUTION LINE
Distribution lines transmit electricity from substations to customers’ homes and businesses. They can be suspended overhead on utility poles or buried underground Across PSE’s distribution system, about half the lines are overhead, and the other half run underground.
DISTRICT REGULATOR
A district regulator is a device that is made up of piping, valves, control instruments and lines that automatically regulates natural gas pressure in the main pipeline to which it is connected.
DOUBLE-CIRCUITED
Double-circuiting is a way to double the amount of power serving an area. For instance, it could be placing six lines on a transmission pole instead of three. This added power is a way to ensure more reliable service for customers.
EASEMENT
An easement is a legal right to use another's land for a specific, limited purpose. For PSE, this means installing and accessing infrastructure (like utility poles and other equipment) within the designated easement area. When an easement is granted by a property owner, it’s granting the legal right to use the property – but the legal title to the land itself remains with its owner. It is common for an easement to be granted in perpetuity. Learn more at PSE | Easements.
ELECTRIC GRID
The grid refers to the electric system and its network of power lines, substations, transformers, and other equipment that safely deliver electricity to customers from where it's generated.
ENERGY EFFICIENCY
Energy efficiency tools help PSE and customers use less energy and reduce our carbon footprints. Examples include LED bulbs, smart thermostats, and heat pumps. PSE offers a wide variety of efficiency programs and rebate offers. Learn more at PSE | Get Rebates to Lower Your PSE Bills
ENERGY STORAGE
Energy storage is a means of capturing energy and storing it for later use. Examples include battery energy storage systems (BESS) and pumped storage. Hydrogen (H2) can also serve as energy storage since it can be generated and contained for whenever it’s needed.
FERC
The Federal Energy Regulatory Commission (FERC) is an independent agency that regulates the interstate transmission of electricity, natural gas, and oil.
FIBER-OPTIC LINE
A fiber-optic line is a glass or plastic optical fiber that is often used for communication or transferring data. PSE uses fiber optic lines to help operators monitor our system’s performance remotely.
GATE AND LIMIT STATIONS
Gate and limit stations are devices in our natural gas system that regulate the pressure of the natural gas. Specifically, they decrease the pressure of the natural gas for use in residences and businesses.
GENERATION
Generation is the way energy is produced. All electricity must be generated, and that can happen in a number of ways. For instance, it can be produced at a power plant (typically with fossil fuel) or with renewables like wind, solar, or hydropower.
GRID MODERNIZATION
Grid modernization is PSE’s overarching term for system improvements that make our electric grid cleaner, more reliable, and better prepared to meet our customers’ changing needs. With more EV charging, shifts toward electrification, and more customers with batteries and solar panels, grid modernization will help our electric system adapt safely and reliably. PSE’s investments include everything from smart technology to structural improvements that support the overall health of our system. Learn more about PSE | Grid Modernization.
HORIZONTAL DIRECTIONAL DRILL (HDD)
Horizontal Directional Drilling (HDD) is a method for installing underground utilities with minimal disruption to the surface. PSE might use HDD to create a tunnel for running power lines beneath the bottom of a stream or lake – or under roadways for electric cables and natural gas pipelines.
HYDROGEN (H2)
Hydrogen is an element that’s gaining popularity as a potential fuel for reducing carbon emissions. H2 is made by extracting hydrogen molecules from other substances, like water or methane. Green hydrogen is generated using renewables like wind and solar and is considered a zero-carbon fuel. Turquoise hydrogen is made from natural gas by removing the carbon in a solid form, leaving cleaner fuel for industrial applications. Learn more at PSE | Lower Carbon Fuels.
INTERMITTENT GENERATION
Renewable energy resources, like wind and solar, are considered intermittent because they don’t supply energy consistently. Sometimes, when there’s a lot of wind, they generate more energy than we need. Other times, when the sun doesn’t shine, they can’t produce enough to meet customer demand. This is why pairing battery storage with intermittent generation is so helpful. Batteries can store excess renewable energy or provide a dispatchable resource whenever it’s needed.
LIQUEFIED NATURAL GAS (LNG)
LNG is a cooled form of the natural gas used in customers’ homes. The result is a liquid fuel that takes up less space and is easy to store and transport. LNG is helping industries like maritime shipping reduce their carbon emissions because it’s cleaner than traditional transportation fuels.
LOAD
Load is the amount of power draw placed on the electric system, and it varies based on customer usage. For instance, an industrial building carries a much higher load than a singlefamily home. In a customer’s home, a central air conditioner generally places a much higher load on a circuit than a portable fan. To ensure PSE has enough capacity as customers’ energy needs change over time, we measure load on our system 24/7. That way, we know when it’s time to build new infrastructure or utilize other measures, like energy efficiency programs.
LOOP
A looped system distributes electricity through a service area before returning it to the point of origin. Loops make our system more flexible and reliable by providing more than one source of power to an area. For instance, they can reroute electricity when we’re performing maintenance or help minimize the impacts of outages.
MAIN (AS IN NATURAL GAS MAIN)
Mains are the pipelines that carry natural gas through a portion of the distribution system. For details about mains and other system components.
MAINTENANCE
PSE works hard throughout the year to maintain our electric and natural gas systems. This upkeep can include anything from replacing poles and wires to making sure our existing equipment is performing safely and reliably.
MICROGRIDS
Although microgrids can vary widely in size and design, they’re basically localized systems that can generate and deliver energy – like solar panels combined with a battery system. They can function alongside the main grid, or independently in island mode during an outage.
NATURAL GAS
Natural gas is a fossil fuel composed almost entirely of methane. Interstate pipelines transport natural gas to regional natural gas systems, where it is metered and delivered through a network of local mains, service lines and, ultimately, to customer homes and businesses.
NATURAL GAS SYSTEM AND COMPONENTS
The natural gas system encompasses all the facilities and equipment that safely deliver natural gas to our customers, 24/7.
NERC
The North American Electric Reliability Corporation (NERC) is a not-for-profit international regulatory authority whose mission is to assure the effective and efficient reduction of risks to the reliability and security of the grid. NERC develops and enforces Reliability Standards; annually assesses seasonal and long‐term reliability; monitors the bulk power system through system awareness; and educates, trains, and certifies industry personnel. NERC’s area of responsibility spans the continental United States, Canada, and the northern portion of Baja California, Mexico.
OPERATIONAL FLEXIBILITY
Operational flexibility is the electric system’s ability to adapt to changes and challenges, as well as its compliance with transmission and distribution planning guidelines. Building redundancy into our system helps increase operational flexibility, too. It ensures we can continue to serve energy to our customers even when there are challenges on the system.
OVERHEAD WIRES
Overhead wires are the power lines that are suspended on utility poles and transmission towers. The sizes of wires and poles can vary, depending on the amount of power they’re designed to carry.
OVERLOAD
An overload happens when the demand for electricity exceeds what equipment, or an electric system, is designed to safely deliver.
PLANNED POWER OUTAGE
Sometimes, making improvements to our electric system requires a planned power outage. By temporarily turning off the power to a home or neighborhood, PSE can ensure the safety of crews and customers until work is completed. We know being without power is inconvenient, so we do our best to notify customers in advance. Learn how to prepare for a planned outage at PSE | Planned Power Outages.
PLANNING GUIDELINES
PSE’s System Planning department develops long-term energy delivery plans for our energy systems. This ensures that PSE is prepared to meet communities’ growing and changing needs. Planners follow established guidelines (ranging from PSE to Federal guidelines) to identify system needs and develop safe, reliable, and cost-effective solutions.
RADIAL LINE
A radial line is a single electrical path that has one electric power source and power flowing in one direction, from one end to another end. Radial distribution lines are more vulnerable to reliability issues because they have no backup energy source during an outage.
RECLOSER
Reclosers are devices that can sense where interruptions are happening on our power lines. Working together, they pinpoint a line issue, isolate it, and minimize impacts on the surrounding system. Sometimes, they can even automatically reenergize faulted lines without needing a service crew.
RECOMPRESSION
Recompression helps PSE reduce emissions when we do routine work on our natural gas system. Pipelines use pressure to propel natural gas through our system, but they must be depressurized for crews to work safely. Instead of depressurizing lines by releasing natural gas into the atmosphere, recompression technology captures, recycles, and reuses that gas so it stays in the pipes. This allows us to perform our work safely, while also reducing our carbon footprint.
RELIABILITY
Reliability means fewer power outages for customers – or outages that don’t last as long. PSE is always working to improve reliability with system planning projects and other initiatives. We track electric service reliability across our system, which helps us identify areas for improvement projects.
RENEWABLE ENERGY RESOURCES (ALSO KNOWN AS RENEWABLES)
Renewable energy comes from resources that are naturally replenished, like sunlight, wind, and geothermal heat. Many renewables have a zero (or low) carbon footprint, which makes them a crucial component in PSE’s decarbonization strategy.
RENEWABLE NATURAL GAS (RNG)
RNG is an alternative fuel that can help natural gas users reduce their carbon footprints. PSE offers participating customers an RNG option that comes from organic waste matter. It’s been transformed and refined into pipeline-quality gas that can replace a portion of their conventional natural gas use.
RESILIENCY
A resilient electric grid is designed to withstand, or bounce back more quickly, from disruptions. This could include impacts from events like storms, extreme temperatures, or wildfires. PSE is investing in many improvements that “harden” our system, like tree wire, equipment upgrades, and sometimes moving power lines underground.
RIGHT OF WAY (ROW)
Right of Way is the legal right, established by usage or grant, to pass along a specific route through grounds or property belonging to another. ROW are often owned by a county, city, or municipality.
SCADA
Supervisory Control and Data Acquisition (SCADA) is a computerized system PSE uses to remotely monitor and control equipment (like substations) in real time. Our system operators use SCADA to identify and respond to issues faster, reduce outage durations, and safely increase efficiency across our grid.
SERVICE LINE
A service line is a lower-voltage (120 to 480 volts) overhead or underground electric line that is the last connection from PSE to the meter on customers’ homes or businesses.
SINGLE-CIRCUITED
Single-circuiting is having three lines on a transmission pole, which is half the amount of a double-circuited line.
SITING
Siting is the process of finding the best location for new infrastructure. PSE considers a lot of different factors when determining equipment sites. Minimizing community and environmental impacts are big considerations, which is why co-locating is always our preference, whenever possible.
SMART STREET LIGHTS
Smart Street Lights can be remotely monitored and managed in real time. Communities that partner with PSE on these installations can make lighting adjustments, whenever needed, to meet their local priorities. Lights can be instantly turned on/off or dimmed to conserve energy or reduce light pollution at night. Monitoring each light means broken and failing lights can be quickly identified and repaired.
SUBMARINE CABLE
Submarine cables run underwater – across the bottom of a lake or stream – to carry electricity or natural gas from one area to another.
SUBSTATION
Substations are a vital component of an electric system. Their primary function is using transformers to “step down” incoming electricity to a lower voltage before reaching customers’ homes and businesses.
SWITCHING STATION
A switching station is a substation that reroutes power flow from one line or path to another. They can also integrate power from multiple sources on the local grid (like Bonneville Power Administration). Unlike substations that serve neighborhood circuitry, switching stations do not step power voltage up or down.
TARGETED ELECTRIFICATION
One way to reduce dependence on fossil fuels is by replacing natural gas appliances with electric ones – like using an electric heat pump, instead of a gas furnace, to heat your home. Through PSE’s targeted electrification pilot program, and future initiatives, natural gas customers can transition to electric technologies that lower their carbon footprint and contribute to our state’s clean energy transition.
TOWN BORDER STATION
A town border station is a facility where natural gas changes ownership from a transmission operator to a local distributor. PSE receives natural gas from transmission operator Williams Northwest Pipeline at our North Seattle town border station. We then reduce its pressure so it can be delivered to customers’ homes and businesses through our natural gas distribution system.
TRANSFORMER
Transformers are devices that adjust electricity to a higher or lower voltage. As electricity travels from its generation source to customers, its voltage is transformed at various stages along the way – like at substations that “step down” voltage to levels safe for homes and businesses. Transformers can also be mounted on utility poles, in silver-colored canisters, and housed on the ground in green metal boxes.
TRANSMISSION AUTOMATION (TA)
Transmission automation uses devices to detect where faults have occurred on our transmission lines – usually caused by trees and limbs. Once a fault has been detected, TA can isolate it and keep nearby lines operating normally. TA offers many benefits for PSE and customers, like improving transmission grid reliability, decreasing customer power outages, reducing damage to substation equipment, and lowering the risk of wildfires caused by faults on the transmission grid.
TRANSMISSION LINE
Transmission lines are high-voltage lines that carry electricity from generation plants to substations, or from substation to substation. Before sending electricity onward to customers, substations use transformers to "step down" the transmission voltage (55 to 230 kilovolts) to our primary distribution voltage (12.5 kV).
TREE WIRE
Tree wire is a type of specially-coated power line that's designed to prevent electric shorts from fallen tree limbs. This added protection can significantly reduce the frequency of branch-related outages.
UNDERGROUNDING
Undergrounding means burying power lines beneath the ground. There are times when undergrounding is a more feasible option, or provides more benefits, than suspending lines on overhead utility poles.
VEGETATION MANAGEMENT
Trees are the number one cause of outages! PSE’s vegetation management programs work throughout the year to protect power lines from the impacts of trees and limbs. Programs include pruning, tree removal, and planting guidelines for customers. Learn more at PSE | Tree Trimming.
VOLTS AND KILOVOLTS
A volt is a unit of electromotive force. The higher the electric voltage, the more its energy “pushes” forward in a circuit. One kilovolt (kV) equals 1,000 volts, and PSE typically uses kilovolts to describe system elements like distribution lines, solar panels, and batteries.
MEGAWATT (MW) AND MEGAWATT HOUR (MWh)
One megawatt (MW) is equal to 1,000,000 watts of electric energy. PSE uses megawatts as a standard measurement when referring to things like system load and peak demand. A megawatthour (MWh) equals 1,000 kilowatts of electricity generated per hour and is used to measure electric output.