E

earth ground: A low-impedance path to earth that discharges lightning, static, and radiated energy, and keeps the main service entrance at earth potential.
earthing electrode: A ground electrode, water pipe, building steel, or some combination of these, that establishes a building s earth ground.
ECL: Emitter-coupled logic; extremely high-speed electronic circuitry where very fast switching between specific voltage levels rather than semiconductor saturation and cutoff determine changes in binary logic.
eddy currents: Induced currents in transformer windings and core caused by the magnetic field from the normal alternating current and harmonics.
effective value: For any time-variant voltage or current waveform, the constant value that gives the same average power. For sinusoidal waveforms, the effective value equals 0.707 times the peak value.
efficiency: The percentage of input power that a device uses expressed mathematically as the ratio of output power to input power: efficiency = P _o/ P _i , where P _ois power output in watts, P _iis power input in watts.
EHV: Extra-high voltage; covers voltages from 345 to 800 kV.
electromagnetic compatibility: The ability of a device or system to operate satisfactorily without causing electromagnetic disturbances to another device or system.
electric field: Describes forces associated with electrical charges.
electrical degree: Allows mathematical relationships between various electrical quantities. One cycle of ac power passes through 360 .
electrode: Generally, a conducting medium through which an electric current enters or leaves a different medium, such as an electrolyte, gas, or vacuum.
electrolyte: Any substance that in solution...

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