PEC电气工程专业英语证书考试-电气工程专有名词2.doc

PEC电气工程专业英语证书考试-Glossary of Electrical Engineering Terms2 A *absolute value?Value of an expression without regard to sign or phase angle. *absolute zero?The temperature where thermal energy is at minimum. -273.15?C or 0 Kelvin. *ac?[see alternating current] *accessory?A device, other than current using equipment, associated with such equipment or with the wiring of an installation. *acceleration?Rate of change of velocity. [Unit: m/s2] *acceleration due to gravity g?Acceleration of a body falling freely in a vacuum as a result of the gravitational pull of the earth. g = 9.807 m/s2 *accumulator?Storage battery or secondary cell for storing electricity. *accuracy?Specifies the nearness of the measured value from the true value. *acid?Containing an excess of hydrogen ions over hydroxyl ions. *acoustics?Study of sound. *a c potentiometer?An apparatus for the comparison of a.c. voltages. Balance requires both the magnitude and the phase angle of the unknown voltage to be balanced with the known voltage. This may be done either in cartesian form or in polar form. *acre?Unit of area in the Imperial system. 1 acre = 4047 m2?= 0.4047 hectares *active element?An element capable of generating electrical energy. *active filter?Any filter using an op amp is called an active filter. *actuator?Mechanical part of a limit switch that uses mechanical force to actuate the switch contacts. *acute angle?An angle of less than 90o. *address?The number that uniquely identifies the location of a word in memory. *adiabatic?process taking place without heat entering or leaving the system. *admittance?Reciprocal of impedance. Ratio of the electric current to the voltage. [Unit: siemens or S] *aerodynamics?Study of air moving around solid objects, or air flowing around a stationary structure. *air conditioning?The control of temperature, humidity and the purity of the air. In tropical countries like Sri Lanka, air conditioning only cools the air and not heats it, but in cold countries both mode