353 articles
Cold load pickup
Cold load pickup is the abnormally high demand that appears when electrical loads are re-energized after an outage, reaching several times normal levels and tripping protective relays.
Compact transmission line
A compact transmission line is an overhead power line built with reduced phase spacing and shorter insulators, so more power flows through a narrower right-of-way than a conventional design allows.
Composite insulator
A composite insulator is an electrical insulator for overhead power lines combining a fiberglass core rod, silicone rubber housing, and metal end fittings, giving high tensile strength at low weight.
Compression splice
A compression splice is a tubular metal fitting crimped onto the two ends of an overhead power conductor, forming a full-tension joint that carries both mechanical load and electrical current.
Concrete pole
A concrete pole is a utility pole made of reinforced or prestressed concrete, supporting power and telecom lines; typically spun, it resists fire, rot, and termites, and lasts roughly 60 years.
Conductor cover-up
Conductor cover-up is temporary insulating equipment, such as rubber line hose, blankets, and hoods, that utility line workers place over energized conductors to prevent accidental contact during live-line maintenance.
Conductor icing
Conductor icing is the buildup of atmospheric ice on overhead power line conductors, a major weather-related threat to power grids that adds load and can cause line failures.
Conservation voltage reduction
Conservation voltage reduction (CVR) is a grid technique in which utilities lower feeder voltage a few percent to cut energy use, peak demand, and line losses.
Constant-voltage transformer
A constant-voltage transformer, or ferroresonant transformer, keeps output voltage nearly constant despite wide input swings using magnetic core saturation and a resonant capacitor, with no electronics or moving parts.
Converter transformer
A converter transformer is a power transformer that connects an AC network to power-electronic converter valves, chiefly in HVDC transmission stations and industrial rectifier plants.
Corona loss
Corona loss is the power dissipated when air around a high-voltage conductor ionizes, an effect of voltage that matters mainly on lines of 345 kV and higher.
Corona ring
A corona ring is a circular conductive fitting, usually a metal toroid, attached to high-voltage equipment terminals to spread the electric field gradient and prevent corona discharge, reducing noise and radio interference.
Covered conductor
A covered conductor is an overhead power line conductor with an insulating outer layer, used to reduce faults and fire ignition when vegetation or animals contact the wire.
Crest factor
Crest factor is the ratio of a waveform's peak value to its RMS value, a measure of peakiness; a sine wave has a crest factor of 1.414.
Cross-bonding
Cross-bonding is a sheath-bonding method for three-phase systems of single-core power cables in which the metallic sheaths are cross-connected between sections so induced voltages cancel, suppressing circulating currents and limiting sheath voltages.
Crossarm
A crossarm is a structural beam bolted near the top of a utility pole that supports conductors, insulators, and transformers on overhead distribution and transmission lines.
Crossing tower
A crossing tower is a transmission tower built at a wide obstacle such as a river, strait, or valley, where the line must span far farther than normal.
CT saturation
CT saturation is the condition where a current transformer's magnetic core saturates, so its secondary current is distorted and no longer proportional to the primary current.
Current transformer
A current transformer (CT) is an instrument transformer that scales high primary currents down to standard values, typically 5 A or 1 A, for meters and protective relays.
Current-source converter
A current-source converter is a power electronic converter that holds a stiff DC current behind an inductor; in HVDC it is known as the line-commutated converter.
Curtailment (renewable energy)
Curtailment is the deliberate reduction of wind or solar power plant output when the grid cannot absorb the electricity, due to transmission limits, stability needs, or supply-demand imbalances.
Data logger (electric power)
A data logger for electric power is an instrument that automatically records quantities such as voltage, current, power, and energy for hours to months, without an operator present.
DC circuit breaker
A DC circuit breaker is a switching device that interrupts direct current in DC power systems; unlike AC breakers, it must create a current zero artificially and dissipate stored energy.
DC connector
A DC connector, also called a DC plug, is an electrical connector for direct current, from power adapters to 1,500 V photovoltaic strings and EV charging.
Dead-end clamp
A dead-end clamp, also called a strain or tension clamp, is overhead line hardware that terminates a conductor and carries its full tension into a pole or tower.
Demand response
Demand response is the reduction or shift in electricity consumption by customers in response to price signals, incentive payments, or grid reliability needs, helping balance supply and demand.
Dennis A. Woodford
Dennis A. Woodford is a Canadian power systems engineer from Winnipeg, Manitoba, who created the EMTDC/PSCAD simulation software, co-founded Electranix Corporation, and was elected to the US National Academy of Engineering in 2017.
Differential protection
Differential protection is a unit-protection technique in electrical power engineering that compares currents entering and leaving a zone, such as a transformer or busbar, and trips when the difference exceeds a threshold.
Directional overcurrent relay
A directional overcurrent relay, ANSI device 67, combines overcurrent and directional elements so it trips only for fault current above pickup flowing in a preset direction.
Distance relay
A distance relay is a protective relay, designated ANSI device 21, that measures voltage-to-current ratio to detect and locate faults within a set electrical distance of a power line.