Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 188)

Glossary
AC Alternating current.
AC Contacto An alternating current (AC) contactor is designed for the specific purpose of
establishing or interrupting an AC power circuit.
Alphanumeric Display A device capable of displaying characters (letters, numbers, and symbols) but not
graphics.
Ambient Temperature Ambient temperature is the temperature of air, water, or a surrounding medium
where equipment is operated or stored.
American Wire Gauge A standard system used for designing the size of electrical conductors. Gaug
(AWG) numbers have an inverse relationship to size; larger numbers have a smaller cross-
sectional area. However, a single-strand conductor has a larger cross-sectional
area than a multi-strand conductor of the same gauge so that they have the same
current-carrying specification.
Axis A principal direction along which movement of the tool or workpiece occurs. The
term axis also refers to one of the reference lines of a coordinate system.
Back of a Motor The back of a motor is the end which carries the coupling or driving pulley
(NEMA). This is sometimes called the drive end (D.E.) or pulley end (P.E.).
Base Speed Base speed is the manufacturer’s nameplate rating where the motor will develop
rated HP at rated load and voltage.
Bearing (Ball) A “ball” shaped component that is used to reduce friction and wear while
supporting rotating elements. For a motor, this type of bearing provides a relatively
rigid support for the output shaft.
Bearing (Roller) A special bearing system with cylindrical rollers capable of handling belted load
applications too large for standard ball bearings.
Braking Braking provides a means of stopping an AC or DC motor and can b
accomplished in several ways:
• DC-injection (AC Drives) – A method which produces electromagnetic
braking forces in the motor by removing two AC motor (stator) phases and
injecting the DC current. The result is a linear braking characteristic (ramp)
that does not diminish with motor speed. Application is normally limited to
10-20% of rated motor speed due to increased heating in the rotor.
• Dynamic Braking (AC Drives – Since AC motors do not have separate
excitation, dynamic braking is accomplished by continuing to excite the moto
from the drive. This causes a regenerative current to the drive’s DC
intermediated Bus Circuit. The Dynamic Brake resistors are then placed
across the DC bus to dissipate the power returned. The brake resistor is usually
switched by a transistor or other power switch controlled by the drive.