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ac-coupled amplifier An amplifier with a capacitive-coupled input to filter out the dc component of the input signal.
ac input circuit A circuit on a PLC I/O module that converts ac signals from a pilot switch voltage level to backplane logic-level dc signals.
ac input module An I/O module for a PLC or other controller that contains circuits that convert ac signals to backplane logic-level dc signals.
ac output circuit A circuit on a PLC UO module that converts backplane logic-level dc signals to field-level ac voltage.
ac output module A PLC I/O module that contains circuits that convert backplane logic-level dc signals to field-level ac voltage.
across-the-line starter A motor starter that allows full voltage to be applied to a motor when the contacts of the starter are closed.
actuator A device that converts an electrical signal into motion.
address A character string that uniquely identifies a memory location in a PLC, computer, or other programmable system.
alternating current Current that changes from a positive level to a negative level periodically. Example: a 60 Hz alternating current change from positive to negative 60 times per second.
ambient temperature The temperature of the medium (air, water, earth).
American wire gauge (AWG) A standard used for identifying the size of electrical conductors. Gauge numbers have an inverse relationship to size: larger numbers have a smaller cross-sectional area.
analog circuit A circuit in which the signal can vary continuously between specified limits from some minimum to some maximum.
analog input module A PLC UO module that contains circuits that convert analog dc input signals to digital values.
analog output module A PLC UO module that contains circuits that convert digital values to an analog dc signal.
analog-to-digital conversion (A/D conversion) A circuit that converts analog values to digital (numerical) values.
angstrom Unit of measure for the wavelength of light. 1 ångström (Å) = 10–10 meters = 0.1 nm
ANSI American National Standards Institute. An organization in the United States that develops standards for industry.
armature The moving part of a magnetic circuit, such as the rotating part of a motor or a generator or the movable iron part of a relay.
ASCII American Standard Code for Information Interchange. It is a seven-bit code with an optional parity bit used to represent alphanumerics, punctuation marks, and control-code characters.
This page was last updated: Tuesday, August 19, 2008 23:44