Watlow CPC400 - Manual (Page 211)

CPC400 Series User’s Guide Glossary
Doc. 0600-2900-2000 Watlow Anafaze 197
cations over a short distance (50 feet [15 m] or
less) and to a single device.
EIA/TIA-485 — A standard for electrical
characteristics of generators and receivers for
use in balanced digital multipoint systems.
This is usually used to communicate with mul-
tiple devices over a common cable or where
distances over 50 feet (15 m) are required.
Electrical Noise
See Noise.
Electromagnetic Interference (EMI)
Electrical and magnetic noise imposed on a sys-
tem. There are many possible causes, such as
switching ac power inside the sine wave. EMI can
interfere with the operation of controllers and
other devices.
Electrical-Mechanical Relays
See Relay, Electromechanical.
Emissivity
The ratio of radiation emitted from a surface
compared to radiation emitted from a blackbody
at the same temperature.
Engineering Units
Selectable units of measure, such as degrees Cel-
sius or Fahrenheit, pounds per square inch, new-
tons per meter, gallons per minute, liters per
minute, cubic feet per minute or cubic meters per
minute.
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 is °C = 5/9 (°F -
32).
Failed Sensor Alarm
Warns that an input sensor no longer produces a
valid signal.
Filter
Filters are used to handle various electrical noise
problems.
Digital Filter — A filter that slows 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 Filter — A filter that slows the
change in the response of the heat or cool out-
put. 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
time, usually measured in cycles per second. Also
referred to as Hertz (Hz).
G
Gain
The amount of amplification used in an electrical
circuit. Gain can also refer to the proportional (P)
mode of PID.
Global Alarm
Warns that one or more alarm conditions exist by
activating a digital output.
Ground
An electrical line with the same electrical poten-
tial as the surrounding earth. Electrical systems
are usually grounded to protect people and equip-
ment from shocks due to malfunctions. Also
referred to as “safety ground.”
H
Hertz (Hz)
Frequency, measured in cycles per second.
High Deviation Alarm
Warns that the process has risen more than a
certain amount above set point. It can be used as
either an alarm or control function.
High Power
(As defined by Watlow Anafaze) Any voltage
above 24 VÅ (ac) or VÎ (dc) and any current level
above 50 mAÅ (ac) or mAÎ (dc).
High Alarm
A signal that is associated with a set maximum
value that can be used as either an alarm or
boost control function.
HMI
Human-machine interface.
Hysteresis
Control Hysteresis — The range through
which a variation of the input produces no
noticeable change in the output. In the hyster-
esis, specific conditions can be placed on con-
trol output actions. Operators select the
hysteresis. It is usually above the heating pro-