EIF Module 4 Unit A

transformer

a device that transfers power from one circuit to another; step‐up transformers increase voltage from the primary to the secondary circuit while lowering current proportionally, while step‐down transformers lower voltage from the primary to the secondary circuit while raising current proportionally

current (amps)

a flow of electrons in an electrical conductor; the strength or rate of movement of the electricity is measured in amperes (amps)

substation

a location along a transmission or distribution route containing equipment to transform and route power

resistance

a measure of the degree to which an electrical component opposes the passage of current; resistance is measured in ohms

voltage drop

a reduction in voltage between the source and load in an electrical circuit caused by electrical resistance

subtransmission system

a subsystem of the electric power transmission system that carries voltages that are reduced from the major transmission line system that is typically routed to distribution stations

step‐up transformer

a transformer that has fewer turns in the primary winding than in the secondary winding; the voltage in the primary circuit will be less than in the secondary circuit

step‐down transformer

a transformer that has more turns in the primary winding than in the secondary winding; voltages are higher in the primary circuit than in the secondary circuit

switching station

also known as a switchyard, it is the area at a generating station that transforms and routes power to be entered into the transmission system

Alternating Current (AC)

an electric current that reverses its direction at regularly recurring intervals

oscilloscope

an electronic measuring instrument that displays the waveforms created by an electrical current

electric power transmission system

an interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers or is delivered to other electric systems

distribution circuit

circuits that transmit lower voltages from the substation

stepped up

conversion of high‐voltage electricity to higher voltage through the use of transformers at power substations

stepped down

conversion of high‐voltage electricity to lower voltage through the use of transformers at power substations

direct current (DC)

current which moves in only one direction; DC results from a constant polarity power source

hertz (Hz)

cycles per second; the unit of measurement for frequency

Circuit Breaker

device that protects a transformer from being overloaded with current and malfunctioning or blowing

electrical energy

electrical energy is the generation or use of electric power over a specified amount of time; electrical energy is expressed in kilowatt‐hours (kWh)

Corona loss

energy loss that results from electrical stresses at the conductor surface and result in ionization of the surrounding air

power

in the context of electricity transmission, power is defined as a rate at which electricity (electrical energy) is produced; power is measured in watts (W) or megawatts (MW); power is a variable that must be considered when dealing with transmission system capability and capacity design and function

electrical power grid

interconnected electric generation, transmission, and distribution systems over broad geographic areas

Conductor

materials such as copper and aluminum that allow electrical current to flow freely through them; in electric power transmission, conductor is also the term used for the actual "power line" or cable

insulators

materials such as glass and fiberglass that do not allow electrical current to flow through them; in electric power transmission, the term insulator also refers to the piece of equipment that is used to attach transmission lines that support the conductor and other conductor attachment points.

reactance

opposition to the flow of an alternating electric current caused by the buildup of electric or magnetic fields due to the current

transmission system

see "electric power transmission system"

transmission

see "electric power transmission"

ground wires

set of wires attached directly to the transmission tower so that current from a lightning strike flows to the ground; also called shield wires

load (electric)

the amount of electric power required by consumers (demand)

electric power transmission

the bulk transfer of high‐voltage electrical energy from its source at generating plants to substations

transmission switching

the connecting and disconnecting of transmission lines or other components to and from the system

voltage (volts)

the difference in electrical potential between any two conductors or between a conductor and ground; it is a measure of the electric energy per electron that electrons can acquire and/or give up as they move between the two conductors

thermal limit

the maximum amount of power a transmission line can carry without experiencing heat‐related deterioration

frequency

the number of cycles of alternating polarity per second; an AC voltage source reverses the direction of electric charge many times per second; measured in cycles per second (hertz or Hz)

generator

the portion of the generating unit where the rotating mechanical energy is converted to electrical energy; it consists of a stator containing the armature windings and a rotor (center shaft) that is turned by the turbine to produce the magnetic field

distribution system

the portion of the transmission and facilities of an electric system that is dedicated to delivering electric energy to an end user

right of way (ROW)

the right of way for a transmission system consists of the land set aside solely for the use of transmission towers, lines, and other facilities; right of ways serve as safety mechanisms to maintain clearance areas between the transmission lines and surrounding structures or trees and other vegetation

transmission tower

the rigid support structure that is used to support electric power transmission conductors (cables)

generating plant switchyard

where power is transformed and routed to the transmission system