Rockwell Automation SA3100 AutoMax Distributed Power System - Manual (Page 52)

A-8 AutoMax Distributed Power System Overview
multimode (fiber-optic cabling): a type of light propagation in which all of the light rays
do not travel in parallel with the axis of the fiber. Since the light rays follow different
paths in the fiber, their transit times will differ. The difference in transit times results in
a specific bandwidth that the multimode fiber can support.
nanometer: one-billionth of a meter (10
-9
).
NEC: National Electrical Code; the recommendations of the National Fire Protection
Association, revised every three years. City or state regulations may differ from NEC
recommendations and take precedence over them.
NEMA: National Electrical Manufacturers Association; a non-profit organization
whose members include manufacturers of electrical equipment and supplies. Some of
the standards NEMA specifies are: HP ratings, speeds, frame sizes and dimensions,
torques, and enclosures.
numerical aperture (of optical fiber): the range of angles at which a light beam must
enter a fiber cable in order to be reflected and transmitted; a measure of the angular
acceptance of a fiber; the light-gathering capability of the fiber.
operating system (OS): sometimes called “runbase.” In DPS, all Processors, UDC
Modules, and PMIs require operating systems.
optical power: the power emitted from a light source into a fiber-optic cable; defined
in watts but usually expressed in decibels.
optical power budget: the total amount of optical power available from the fiber-optic
transmitter less the losses present in the fiber-optic link.
OS: see operating system.
overshoot: the amount that a controlled variable exceeds the desired value after a
change of input.
overspeed: a speed greater than rated or desired maximum speed (RPM).
parameter (Distributed Power drives): a value used to represent a drive or motor
characteristic, such as “maximum motor RPM” or “current transformer turns ratio.”
Also, in BASIC language LOCAL tunable statements, a value that defines one of the
limits within which a variable can be adjusted, for example, the “HIGH” limit.
phase angle: the displacement between periodic waves of the same frequency.
phase control: in rectifier circuits, the process of varying the point (firing angle) within
the cycle at which forward conduction is permitted to begin through the rectifier circuit
element.
phase-crossover frequency: the frequency at which the phase angle reaches 180
degrees.
phase lag (delay) or phase lead: phase angle of the input wave relative to the output
wave.
phase sequence: the order in which the AC line voltages (line to neutral) successively
reach their positive maximum values.