Watlow CPC400 - Manual (Page 209)

CPC400 Series User’s Guide Glossary
Doc. 0600-2900-2000 Watlow Anafaze 195
Glossary
A
AC
See Alternating Current.
AC Line Frequency
The frequency of the ac line power measured in
Hertz (Hz), usually 50 or 60 Hz.
Accuracy
Closeness between the value indicated by a mea-
suring instrument and a physical constant or
known standards.
Action
The response of an output when the process vari-
able is changed. See also Direct Action, Reverse
Action.
Address
A numerical identifier for a controller when used
in computer communications.
Alarm
A signal that indicates that the process has
exceeded or fallen below a certain range around
the set point. For example, an alarm may indi-
cate that a process is too hot or too cold. See also
Failed Sensor Alarm, Global Alarm, High Devia-
tion Alarm, High Alarm, Loop Alarm, Low Devia-
tion Alarm, Low Alarm.
Alarm Delay
The lag time before an alarm is activated.
Alternating Current (AC)
An electric current that reverses at regular inter-
vals, and alternates positive and negative values.
Ambient Temperature
The temperature of the air or other medium that
surrounds the components of a thermal system.
American Wire Gauge (AWG)
A standard of the dimensional characteristics of
wire used to conduct electrical current or signals.
AWG is identical to the Brown and Sharpe (B&S)
wire gauge.
Ammeter
An instrument that measures the magnitude of
an electric current.
Ampere (Amp, A)
A unit that defines the rate of flow of electricity
(current) in the circuit. Units are one coulomb
(6.25 x 1018 electrons) per second.
Analog Output
A continuously variable signal that is used to
represent a value, such as the process value or
set point value. Typical hardware configurations
are 0 to 20mA, 4 to 20mA or 0 to 5VÎ (dc).
Automatic Mode
A feature in which the controller sets PID control
outputs in response to the process variable and
the set point.
Automatic Reset
The integral function of a PI or PID temperature
controller that adjusts the process temperature
to the set point after the system stabilizes. The
inverse of integral.
Autotune
A feature that automatically sets temperature
control PID values to match a particular thermal
system.
AWG
See American Wire Gauge.
B
Baud Rate
The rate of information transfer in serial commu-
nications, measured in bits per second.
BCD
Binary coded decimal. For BCD job loading, the
binary states of three digital inputs are decoded
as decimal numbers 1 to 8.
Bumpless Transfer
A smooth transition from automatic (closed loop)
to manual (open loop) operation. The control out-
put does not change during the transfer.
C
Calibration
The comparison of a measuring device (an
unknown) against an equal or better standard.
Celsius
A temperature scale in which water freezes at 0°
C and boils at 100° C
at standard atmospheric
pressure. The formula for conversion to the Fahr-
enheit scale is °F
= (1.8 x °C) + 32. Formerly
known as Centigrade.
Central Processing Unit (CPU)
The unit of a computing system that includes the
circuits controlling the interpretation of instruc-
tions and their execution.