Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B User Manual
Page 401
Publication 900-UM007D-EN-E - January 2011
Glossary
D-3
Deviation:
A departure of a controlled variable from a command such as set
point.
Deviation Indication:
A system of indication in which a departure of a
detected value from the set point is indicated.
DIN (Deutsches Institut für Normung):
A German standards agency that
sets world-recognized engineering and industrial standards.
DIN 43760:
The standard that defines the characteristics of a 100
Ω platinum
RTD having a resistance vs. temperature curve specified by a = 0.00385
Ω per
degree.
Drift:
A gradual change over a long period of time that affects the reading or
value. Changes in ambient temperature, component aging, contamination,
humidity, and line voltage all contribute to drift.
Droop:
Controllers using only proportional control can settle at a value below
the actual set point once the system stabilizes. This offset is corrected with the
addition of Integral control in the control algorithm.
Electromagnetic Compatibility:
To conform with CE’s EMC requirements,
equipment or a system must operate without introducing significant
electromagnetic disturbances to the environment or be affected by
electromagnetic disturbances.
Electromagnetic Interference:
There are many possible sources for
electromagnetic interference (EMI) in an industrial control setting. It can
originate as electrical or magnetic noise caused by switching AC power on
inside the sine wave. EMI interferes with the operation of controls and other
devices.
Electromechanical Relay:
A power switching device that completes or
interrupts a circuit by physically moving electrical contacts into contact with
each other. These are used primarily for ON/OFF control operation.
Event:
A programmable ON/OFF output signal. Events can control
peripheral equipment or processes, or act as an input for another control loop.
Event input boards are an option for most Rockwell controllers.
Fahrenheit:
A temperature scale that has 32° at the freezing point and 212° at
the boiling point of water at sea level. To convert Fahrenheit to Celsius,
subtract 32 from °F and multiply the remainder by 0.556.
Full Indication:
A system of indication in which a detected value is indicated
with a setting range.