Rockwell Automation SA3100 AutoMax Distributed Power System - Manual (Page 46)

A-2 AutoMax Distributed Power System Overview
armature resistance: amount of opposition to current flow from the armature circuit.
Measured in ohms on a cold motor.
armature voltage feedback: signal proportional to armature voltage. Used to
regulate Power Module output.
attenuation: signal reduction inherent in a transmission line or cable over a given
distance. The amount of loss is usually stated in decibels per kilometer at a specific
wavelength.
back-to-back converter: see anti-parallel.
bandwidth (fiber-optic communications): the maximum frequency that can be
supported by an optical fiber. This is expressed in Mhz per km of length.
base speed: the speed (RPM) of a DC motor when operating at rated field current,
rated armature voltage, and rated armature current.
bend loss (fiber-optic communications): increased attenuation caused by bending a
fiber cable at a radius smaller than the recommended bend radius.
bend radius, minimum (fiber-optic communications): radius that a fiber cable can be
bent to without damaging the cable.
B/M (Bill of Material): a list of parts, drawings, and instructions to manufacture and
assemble them.
braking: retardation and/or dissipation of the kinetic energy of a motor and driven
machinery. Braking is required in the following conditions:
1. speed reference change or change in direction of motor
2. overhauling load (the driven load attempts to exceed the reference speed)
3. stopping the motor
Braking can be accomplished in several ways:
dynamic braking: for DC drives, slowing the motor by applying a resistive load
across the armature leads after disconnection from the DC supply. This must be
done while the motor field is energized. The motor then acts as a generator until
the energy of the rotating armature is dissipated.
regenerative braking: returning generated power to the line through the reverse
bridge. This provides linear deceleration and is the fastest method of stopping.
motor-mounted or separately-mounted brake: a positive action mechanical
friction device. Normal configuration is such that when the power is removed, the
brake is set. This can be used as a holding brake. A separately mounted brake is
one which is located on some part of the mechanical drive train other than the
motor.
breakout cable: a tightly-buffered multifiber fiber-optic cable.
bridge: For Reliance drives, used to describe the entire package of power devices in a
Power Module.