Rockwell Automation SA3100 AutoMax Distributed Power System - Manual (Page 55)

Glossary A-11
shunt: usually refers to a calibrated meter shunt that produces a low-voltage signal
proportional to the current flow through it.
shunt wound: a DC motor or generator in which field excitation is supplied by a
winding which may be connected in parallel with the armature, but is normally
separately excited.
silicon controlled rectifier (SCR): a solid-state switch, sometimes referred to as a
thyristor. The SCR has an anode, cathode, and control element called the gate. The
device provides controlled rectification. The SCR can rapidly switch large currents at
high voltages.
skeleton file: in AutoMax Programming Executive software, a template file that
provides the required statements for each type of AutoMax or UDC task or
documentation file. The appropriate skeleton file can be copied into a new task to
provide a starting point for developing the task. The Programming Executive contains
skeleton files for the following: the BASIC language Include task (SKELETON.INC),
AutoMax Control Block (SKELETON.BLK), PC/Ladder Logic (SKELETON.PC), UDC
Control Block (SKELETON.UDC), BASIC (SKELETON.BAS), and documentation files
(SKELETON.DOC).
snubber: auxiliary circuit element used to modify transient voltage or current of a
semiconductor device. There are three types: shunt, series, and polarized.
speed loop: an outer control loop using a speed-sensing device to provide speed
feedback for comparison to the speed reference.
speed range: all the speeds that can be obtained in a stable manner by action of the
control equipment governing the performance of a motor. The speed range is
generally expressed as the ratio of the maximum to the minimum operating speed.
speed regulation: the numerical measure in percent of how accurately the motor
speed can be maintained. It is the percentage of change in speed between full load
and no load.
squirrel-cage motor: a type of induction motor. See induction motor.
starting torque: the torque produced by the motor during the starting period.
surge protection: a form of electrical protection in which an abnormal condition
causes disconnection or inhibits connection of the protected equipment in accordance
with the rate of change of current, voltage, or power.
surge suppressor: a device that operates to limit the surge of current, voltage or
power to limit the rise of such quantity (usually voltage) above a predetermined level.
synchronize: to establish a common time base; in DPS communications, the term is
also used to mean to establish communication between the UDC module and PMI
such that feedback messages arrive at the UDC module just before it executes the
UDC task.
task: an application program that runs on an AutoMax Processor or UDC module.
AutoMax task: an application task that runs on an AutoMax Processor; AutoMax
tasks are executed on a priority basis, and share all system data. Application
tasks on different AutoMax Processors in the rack are run asynchronously.