User`s guide

ANASOFT User’s Guide 75
Glossary
A
AC
See Alternating Current.
AC Line Fre
q
uenc
y
The frequency of the AC power line measured in
Hertz (Hz), usually 50 or 60 Hz.
Accurac
y
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 setpoint. For example, an alarm may indicate
that a process is too hot or too cold. See also:
Deviation Alarm
Failed Sensor Alarm
Global Alarm
High Deviation Alarm
High Process Alarm
Loop Alarm
Low Deviation Alarm
Low Process Alarm
Alarm Dela
y
The lag time before an alarm is activated.
Alternatin
g
Current (AC)
An electric current that reverses at regular inter-
vals, and alternates positive and negative values.
Ambient Tem
p
erature
The temperature of the air or other medium that
surrounds the components of a thermal system.
American Wire Gau
g
e (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.
Am
p
ere (Am
p
)
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.
Analo
g
Out
p
ut
A continuously variable signal that is used to rep-
resent a value, such as the process value or set-
point value. Typical hardware configurations are
0-20mA, 4-20mA or 0-5 Vdc.
Automatic Mode
A feature that allows the controller to set PID
control outputs in response to the Process Vari-
able (PV) and the setpoint.
Autotune
A feature that automatically sets temperature
control PID values to match a particular thermal
system.
B
Bandwidth
A symmetrical region above and below the set-
point in which proportional control occurs.
Baud Rate
The rate of information transfer in serial commu-
nications, measured in bits per second.