The object distance is defined as the distance between
the front end of the sensor and the object itself.
Occupational Safety and Health Administration (OSHA)
The United States governmental agency that establishes
and enforces safety standards in the workplace.
Off Delay Logic
Adjustable delay (after input signal stops) before output is de-energized.
Off State Current
Supply or bias current flowing into a solid state device when it is in the
un-actuated state (see Leakage Current).
Sustained deviation between actual control point and setpoint under stable
Unit of electrical resistance. Resistance through which a current of one
ampere will flow when one volt signal is applied.
Current in a circuit is directly proportional to the
voltage, and inversely proportional to resistance. The
complete Ohm's Law also includes the relationships of watts
to amps, volts and ohms. Stated as: E = IR Where: I = Amps,
I = E/R, E = Volts, R = E/I, R= Ohms
The standard PVC cables are not made to operate
continuously within an oily environment. PUR and Teflon
covered cables are available.
OLE for Process Control (OPC)
A standard set by the OPC Foundation for fast and easy connections to
On Delay Logic
Adjustable delay (after onset of input signal) before output is energized.
A method of control in which the controller acts as a
switch, turning the final control element either ON or OFF,
depending on the value of the setpoint.
Characteristic of an object that prevents light from passing through. The
opposite of translucent. Opaque objects are easy to detect since they block
light almost entirely.
Control system with no self-correcting action for misses of desired
operational condition, as there is in a closed-loop system. Also refers to a
controller in manual mode.
Open Loop Control
A control system with no feedback signal from the
Operating Characteristics of a Switch
The commonly specified force, torque and linear or angular travel properties
of a switch. Examples: operating or release force, operating point,
Operated Contact Position
Position to which the contacts move when the plunger is traveled to the
operating point or into the overtravel range.
The force which must be applied to the plunger to cause the moving contact
to snap from the normal contact position to the operated contact position.
Actual range over which sensors can be operated. Usage outside the
temperature limits will result in loss of stability, change in operate point and
possible permanent damage to the sensor. Nominal sensing distance is determined
at 25 Degrees C.
Two electronic networks that are connected through an
LED (light emitting diode) and a photoelectric receiver.
There is no electrical continuity between the two networks.
Power or intensity of the projected light available from a particular
emitter; beam intensity.
Output is produced when any one or more inputs are present.
Original Equipment Manufacturer (OEM)
A company that makes basic hardware for other manufacturers to build into
(1) Information leaving a device. (2) Useful energy delivered by a circuit
or device. Can be energy produced at the output terminals of an amplifier, a
source of energy. (3) Control signal action in response to the difference
between setpoint and process variable. (4) Output of the PID controller. In auto
mode the controller calculates the output based its calculation using the error
signal (difference between setpoint and PV). In manual mode, the user sets the
Impedance across the output terminals of a sensor presented by the sensor to
the associated external circuitry.
RMS, peak-to-peak (as specified) AC component of a sensors DC output in the
absence of a change in input pressure.
3-wire proximity switches have a built-in load
resistance. In case of high frequency switching an external
load resistance can be connected in parallel in order to
reduce the time constant.
The form of control output, such as time proportioning,
distributed zero crossing, serial digital-to-analog
converter or analog. Also the description of the electrical
hardware that makes up the output, such as relay, voltage
pulse, or analog.
Modern building codes require certain amounts of fresh air be forced through
public use buildings at all times when occupied to promote good indoor air
quality. This fresh air intake is called outside air. A building that has 30%
outside air means that for each time 100% of the air in the building is
re-circulated, 30% of the re-circulated air is exhausted from the building and
replaced with fresh air from outside. This improves indoor air quality, but
results in an efficiency penalty since the outside air must be heated or cooled,
and humidified or de-humidified to the desired building conditions.
The maximum specified pressure which may be applied to the sensing element
of a sensor without causing a permanent change in the output characteristics.
The amount a process variable exceeds the setpoint during a change in the
system load or change in the setpoint before stabilizing. The opposite condition
is called "undershoot".
As an operating characteristic of a switch, overtravel is the distance
through which the plunger moves when traveled from the operating point to the
full overtravel point. As a characteristic of the actuation applied to the
switch, overtravel is the distance the plunger is driven past the operating