User`s guide

Glossary Series D8 User’s Guide
200 Watlow Anafaze Doc. 0600-3120-2000
Global Alarm
Warns that one or more alarm conditions exist by acti-
vating a digital output.
Ground
An electrical line with the same electrical potential as
the surrounding earth. Electrical systems are usually
grounded to protect people and equipment 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 abo ve set point. It can be used as either an
alarm or control function.
High Power
(As defined by Watlow Anafaze) Any v oltage abo ve
24 Vac or Vdc and any current level above 50 mAac or
mAdc.
High Alarm
A signal that is associated with a set maximum v alue
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 hysteresis, specific con
ditions can be placed on control output actions.
Operators select the hysteresis. It is usually abo ve
the heating proportional band and belo w the cool-
ing proportional band.
Process Hysteresis — In heat/cool applications,
the +/- dif ference between heat and cool. Also
known as process deadband.
I
Input
Analog Input — An input that accepts process
variable information.
Digital Input — An input that accepts on and of f
signals.
Input Scaling
The con verting of input signals to the engineering
units of the process variable.
Input Type
The signal type that is connected to an input, such as
thermocouple, RTD or process.
Instance
An object that is an occurance of a class. Each
instance of a DeviceNet object can have unique values
for its attrib utes and can be e xamined or changed
using the instance services. Class services are used to
examine and change class attrib utes, which af fect all
instances. Instance services are used to e xamine and
change instance attrib utes which affect only that par -
ticular instance.
Integral Control (I)
Control action that automatically eliminates of fset, or
droop, between set point and actual process tempera-
ture.
J
Job
A set of operating conditions for a process that can be
stored and recalled in a controller’ s memory . Also
called a recipe.
Junction
The point where two dissimilar metal conductors join
to form a thermocouple.
K
Keypad Lock
A feature that pre vents operation of the k eypad by
unauthorized people.
L
Lag
The delay between the output of a signal and the
response of the instrument to which the signal is sent.
Linearity
The deviation in response from an e xpected or theo-
retical straight line v alue for instruments and trans-
ducers. Also called linearity error.
Load
The electrical demand of a process, e xpressed in
power (Watts), current (Amps) or resistance (Ohms).