Watlow CLS200 - Manual (Page 231)

CLS200 Series User’s Guide Glossary
Doc.# 0600-3050-2000 Watlow Anafaze 215
A set of technical, scientific and dimensional
standards developed in Germany. Many DIN
standards have worldwide recognition.
Deviation Alarm
Warns that a process has exceeded or fallen
below a certain range around the setpoint.
Digital-to-Analog Converter (DAC)
A device that converts a numerical input sig-
nal to a signal that is proportional to the input
in some way.
Direct Action
An output control action in which an increase
in the process variable, causes an increase in
the output. Cooling applications usually use
direct action.
Direct Current (DC)
An electric current that flows in one direction.
Distributed Zero Crossing (DZC)
A form of digital output control in which the
output on/off state is calculated for every ac
line cycle. Power is switched at the zero cross,
which reduces electrical noise. See also Zero
Cross.
E
Earth Ground
A metal rod, usually copper, that provides an
electrical path to the earth, to prevent or
reduce the risk of electrical shock.
EIA/TIA
See Serial Communications.
Electrical Noise
See Noise.
Electromagnetic Interference (EMI)
Electrical and magnetic noise imposed on a
system. There are many possible causes, such
as switching ac power on inside the sine wave.
EMI can interfere with the operation of con-
trols and other devices.
Electrical-Mechanical Relays
See Relay, Electromechanical.
Emissivity
The ratio of radiation emitted from a surface
compared to radiation emitted from a black-
body at the same temperature.
Engineering Units
Selectable units of measure, such as degrees
Celsius and Fahrenheit, pounds per square
inch, newtons per meter, gallons per minute,
liters per minute, cubic feet per minute or
cubic meters per minute.
EPROM
Erasable Programmable, Read-Only Memory
inside the controller.
Error
The difference between the correct or desired
value and the actual value.
F
Fahrenheit
The temperature scale that sets the freezing
point of water at 32˚ F and its boiling point at
212˚ F at standard atmospheric pressure. The
formula for conversion to Celsius: ˚C = 5/9 (˚F -
32).
Failed Sensor Alarm
Warns that an input sensor no longer produces
a valid signal. For example, when there are
thermocouple breaks, infrared problems or
resistance temperature detector (RTD) open or
short failures.
Filter
Filters are used to handle various electrical
noise problems.
Digital Filter (DF) — A filter that allows the
response of a system when inputs change
unrealistically or too fast. Equivalent to a
standard resistor-capacitor (RC) filter
Digital Adaptive Filter — A filter that
rejects high frequency input signal noise (noise
spikes).
Heat/Cool Output Filter — A filter that
slows the change in the response of the heat or
cool output. The output responds to a step
change by going to approximately 2/3 its final
value within the numbers of scans that are set.
Frequency
The number of cycles over a specified period of