353 articles
Robert J. Creagan
Robert J. Creagan was a Westinghouse nuclear engineer from 1949 into the 1990s, known for analyzing pressurized water reactor limits and holding nuclear fuel patents.
Rotating inertia (power systems)
Rotating inertia in a power system is the kinetic energy stored in synchronized rotating machines, chiefly synchronous generators, which resists frequency changes when generation and load fall out of balance.
Sag (power line)
Sag is the vertical drop of an overhead power line conductor between its two supports, deliberately built in to relieve tension but kept small enough to preserve ground and vegetation clearances.
SAIDI
SAIDI (System Average Interruption Duration Index) is an electric power reliability metric giving the average customer's total sustained outage minutes per year, defined in IEEE Standard 1366.
Schuko
Schuko, short for Schutzkontakt, is a German earthing plug and socket system, plug type F, introduced by Albert Büttner in 1925 and rated 16 A, 250 V.
Sectionalizer
A sectionalizer is an automatic switching device on medium-voltage distribution feeders that isolates faulted line sections by counting the interruption operations of an upstream recloser or breaker.
Security-constrained unit commitment
Security-constrained unit commitment (SCUC) is the optimization problem of scheduling power generators, typically over 24 hours, at minimum cost while respecting transmission limits and credible outages.
Sensus
Sensus is a metering and communications company serving water, electric, gas, and heat utilities, best known for its smart meters and FlexNet radio network; Xylem acquired it in 2016.
Series arc fault detection
Series arc fault detection identifies sustained electric arcs in series with a conductor, most often in the DC circuits of photovoltaic systems, where they pose a fire hazard.
Service drop
A service drop is the overhead conductor assembly carrying electricity from a utility's distribution line, usually the last pole, to a building, where the customer's service entrance begins.
SF6 circuit breaker
An SF6 circuit breaker is a high-voltage switching device that interrupts electrical current in sulfur hexafluoride gas, which combines excellent arc quenching with extreme climate impact.
Shielding angle
The shielding angle, also called the protection angle, is the angle from vertical between an overhead ground wire and the phase conductor it protects on a transmission line.
Short-circuit analysis
Short-circuit analysis is an electrical engineering method for calculating fault currents and voltages in a power system, used to size protective devices and verify equipment ratings.
Short-circuit breaking capacity
Short-circuit breaking capacity is the maximum fault current a circuit breaker or fuse can safely interrupt at its rated voltage, called interrupting capacity in North America.
Short-circuit ratio
The short-circuit ratio (SCR) is a power system metric that quantifies the strength of an AC grid at a point of interconnection, with low values indicating a weak system.
Shunt reactor
A shunt reactor is an inductive device connected in parallel with high-voltage transmission lines to absorb capacitive reactive power, preventing excessive voltages on lightly loaded lines and cables.
Silver Spring Networks
Silver Spring Networks was an American smart grid networking company for utilities and cities, headquartered in Redwood City, California, and acquired by Itron in January 2018.
Single-line diagram
A single-line diagram, also called a one-line diagram, is a simplified drawing of an electrical power system that shows power flow with single lines and standard symbols.
Single-phase electric power
Single-phase electric power, abbreviated 1φ, is alternating current distribution in which all supply voltages vary in unison, serving homes and small buildings while three-phase systems serve industrial loads.
Sinusoidal pulse-width modulation
Sinusoidal pulse-width modulation is a modulation technique that controls a DC-AC inverter by comparing a sinusoidal reference with a high-frequency triangular carrier, reducing output harmonics.
Small-signal stability
Small-signal stability is the ability of a power system to maintain synchronism under small disturbances like load changes, analyzed by linearizing the system around an operating point.
Smart grid
The smart grid, also called grid modernization, is an electricity network upgraded with digital technology and two-way communication so utilities and customers can exchange information and manage energy use.
Smart meter
A smart meter, also called a smart energy meter, is an electronic utility meter that records electricity use in intervals and sends readings to the supplier automatically.
Smoothing reactor
A smoothing reactor is a large inductor connected in series at the DC terminal of an HVDC converter station, smoothing current ripple and limiting fault current.
Soil resistivity
Soil resistivity is the measure of how strongly soil resists conducting electrical current, a basic parameter for grounding, lightning protection, and corrosion control of buried structures.
Solid-state circuit breaker
A solid-state circuit breaker is an electrical protection device that interrupts fault current with power semiconductor switches in microseconds, aimed mainly at fast-rising DC fault currents.
Solid-state transformer
A solid-state transformer (SST) is a power electronics-based device that converts voltage with semiconductor converters and a compact medium-frequency transformer, adding functions like fault current limiting and bidirectional power flow control.
Special protection scheme
A special protection scheme (SPS), also known as a remedial action scheme (RAS) or system integrity protection scheme (SIPS), detects abnormal grid conditions and takes corrective actions such as tripping generators or shedding load.
Spinning reserve
Spinning reserve is the portion of operating reserve from generators already synchronized to the grid and running below full output, able to increase production within about 10 minutes.
Split-phase electric power
Split-phase electric power is a single-phase AC distribution arrangement in which a center-tapped transformer winding delivers 120/240 VAC over three wires, the standard residential supply in North America.