Chap 5 Key Terms 2 Flashcards
conductivity
Capacity of a material to transmit electricity
current
The flow of electricity
current surge
Inrush of electricity caused when electrical devices, such as motors or transformers, are first switched on, at which time they can draw several times their normal operating electrical load; often occurs when circuits are first reenergized following an outage
delta construction
Electric distribution configuration with 3 phases, but no common neutral wire. There is no fixed difference between phase-to-phase and phase-to-ground voltages
distribution lines
In an electric utility system, electric supply lines usually energized between 2.4 and 23kV (contrast with transmission lines)
distribution network
In an electric utility system, the portion that delivers electricity to end-users. Includes distribution substations, primaries, distribution transformers, secondaries, and service lines.
electrical potential (voltage)
Difference in electric energy between another energized conductor and an other energized conductor, the ground, or other object
insulator
Material with poor conductivity–such as fiberglass, glass polymers, and porcelain– used to separate energized conductors from poles or other objects or structures that must not be energized
lockout
Permanent operation that requires manual closure of automatic line reclosers
megawatt
One million watts
minimum vegetation clearance distance (MVCD)
Calculated minimum distance between conductors and vegetation to prevent spark-over, for various altitudes, and operating voltages, that is used in the design of transmission facilities
momentary interruption
Transient fault in an electrical system, lasting from 33 to 133 milliseconds
neutral wire
Common return path for an electric system
North American Electric Reliability Corporation (NERC)
Not-for-profit international regulatory authority whose mission is to assure the reliability of the bulk power system in North America
subtransmission lines
High-voltage lines generally energized between 69 and 161 kV. They can be as low as 35 kV. Subtransmission lines connect bulk transmission substations to industrial customers or distribution substations
supervisory control and data acquisition (SCADA)
System that automatically collects data and enables remote control switching operations
Switchyard
Electric facility that does not change voltage, but is used to route power through various circuits. May be strategically designed to compensate for portions of a system that are experiencing power failures, protecting circuits through disconnect switches, circuit breakers, relays, and communication systems (compare to substation).
taps
Wire connection between energized conductor and other electrical equipment, such as transformers
transformer
Electrical device that raises or lowers voltage through induction
transient fault
fault that affects the dialectic properties of a system for an instant, and no longer exists after the power has been restored
transmission interconnect
Region where transmission or extra-high transmission lines are connected. The interconnection allows utilities to transfer electricity both within their systems and among one another
