Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 199)

Glossary-12
RS-485 An EIA standard that specifies electrical characteristics of balanced-voltage digital
interface circuits in a multi-point link.
SCR Silicon Controlled Rectifier. A solid-state uni-directional latching switch.
Scrolling The vertical movement of data on a display screen caused by the dropping of one
line of displayed data for each new line added at the opposite end.
Self-diagnostic A description of hardware and firmware that monitors its own operation and
indicates any fault it can detect.
Serial Pertaining to time-sequential transmission of, storage of, or logic operations on
data, using the same facilities for successive parts.
Service Factor (S-F) When used on a motor nameplate, a number which indicates how much above the
nameplate rating a motor can be loaded without causing serious degradation (i.e.,
a motor with 1.15 S-F can produce 15% greater torque than one with 1.0 S-F) to
adjust measured loads in an attempt to compensate for conditions which are
difficult to measure or define.
Set Spee The desired operating speed.
Signal The event or electrical quantity that conveys information from one point to another.
Silicon Controlled Rectifier A solid-state switch, sometimes referred to as a thyristor. The SCR has an anode,
(SCR) cathode and control element called the gate. The device provides controlled
rectification since it can be turned on at will. The SCR can rapidly switch large
currents at high voltages. They are small in size and low in weight.
SLC

Controller An Allen-Bradley programmable controller with a name that includes the letters
SLC. See Programmable Controll r.
Slip The difference between rotating magnetic field speed (synchronous speed) and
rotor speed of AC induction motors. Usually expressed as a percentage of
synchronous speed.
SMC Controller An Allen-Bradley Smart Motor Controller.
Special-purpose Moto A motor with special operating characteristics or special mechanical construction
or both, designed for a particular application and not failing within the definition
of a general purpose or definite purpose motor (NEMA).
Speed Rang The speed minimum and maximum at which a motor must operate under constant
or variable torque load conditions. A 50:1 speed range for a motor with a top speed
of 1800 RPM means the motor must operate as low as 36 RPM and still remain
within regulation specification. Controllers are capable of wider controllabl
speed ranges than motors because there is no thermal limitation, only electrical.
The controllable speed range of a motor is limited by the ability to deliver 100%
torque below base speed without additional cooling.