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- Effective Sensing Distance
- Difference between nominal sensing distance and the % manufacturing
tolerance.
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- Electrical Life
- Life of a switch under a specified combination of electrical load,
actuation, environment and criterion of failure. Synonymous with switch life.
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- Electromagnetic Compatibility (EMC)
- The ability of equipment or a system to function as
designed in its electromagnetic environment without
introducing intolerable electromagnetic disturbances to that
environment, or being affected by electromagnetic
disturbances in it.
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- Electromagnetic Interference (EMI)
- Electrical and magnetic noise imposed on a system. There
are many possible causes, such as switching AC power on
inside the sine wave. EMI can interfere with the operation
of controls and other devices.
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- Electromotive Force (EMF)
- Difference of potential produced by sources of electrical energy which can
be used to drive currents through external circuits. Unit is the volt.
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- Emissivity
- For radiamatic inputs, correction factor applied to radiamatic input signal;
ratio of actual energy emitted from the target to energy that would be emitted
if the target were a perfect radiator.
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- Emitter
- The part of a photo electric or ultrasonic sensor which
sends out a signal.
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- Enable
- To allow output in response to an input signal.
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- Enclosed Switch
- A basic switch unit (contact block) enclosed in a durable metal housing. The
enclosure protects the switching unit, provides mounting means, and fitting for
conduit connection.
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- End Points
- Outputs at the specified upper and lower limits of the range.
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- Endurance Limit
- In fatigue testing, the number of cycles which may be withstood without
failure at a particular level of stress.
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- Environment-Proof Switch
- A switch that is completely sealed to ensure constant operating
characteristics. Sealing normally includes and O-ring on actuator shaft and
fused glass-to-metal terminal seals or complete potting and an elastomer
plunger-case seal.
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- Error Correction
- Fast changes in the ambient light (switching of
fluorescent light, welding etc.) might interfere with the
light signal. To suppress this disturbance, an error
correction circuit is built in. The receiver needs at least
two consecutive pulses in order to activate; one pulse will
not activate the sensor output. Dropping a single pulse, due
to interference, will not create a false output signal.
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- Equivalent Dead Time
- To a controller, a process may appear to have more dead time than what it
actually has. That is, the controller cannot be tuned tight enough (without
going unstable) to make the process variable respond appreciably before an
equivalent dead time. More accurately, the characteristic time of the loop is
determined by equivalent dead time consisting of pure dead time plus process
components contributing more than 180 degrees of phase lag.
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- Erosion, Contact
- A general loss of material from one or both working surfaces of a pair of
mating contacts, as a result of switching an electrical load.
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- Error
- Algebraic difference between the indicated value and the true value of the
input pressure. (Error= Setpoint - PV) Usually expressed in percent of full
scale output, sometimes expressed in percent of the sensor output reading. In
auto mode, the controller uses the error in its calculation to find the output
that will get you to the setpoint.
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- Error Band
- Band of maximum deviations of the output values from a specified reference
line or curve due to those causes attributable to the sensor. Usually expressed
as "+-% of full scale output." The error band should be specified as applicable
over at least two calibration cycles, so as to include repeatability, and
verified accordingly.
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- Ethernet
- A local area network to which you can connect data acquisition devices.
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- E-Type Thermocouple
- Chromel-constantan thermocouple with a temperature range of 0 to 800 Degrees
C.
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- Event
- A programmable ON/OFF output signal. Events can control
peripheral equipment or processes, or act as an input for
another control or control loop.
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- Excess Gain
- Ratio of optical power available at a given emitter-to-receiver range to the
minimum optical power required to trigger the receiver.
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- Excitation
- the external source of energy (e.g., electrical voltage or current) applied
to a sensor for its operation.
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- Explosion-Proof
- Having the ability to contain an explosion within the sensor or housing if
it were to occur.
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- Explosion-Proof Enclosure
- An enclosure designed to withstand an explosion of gases
inside, to isolate sparks inside from explosive or flammable
substance outside, and to maintain an external temperature
that will not ignite surrounding flammable gases or liquids.
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- Explosion-Proof Switch
- UL listed switch capable of withstanding an internal explosion of a
specified gas without ignition of surrounding gases.
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- Extension Wire
- See Thermocouple
Extension Wire
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- External Transmitter Power Supply
- A DC voltage source that powers external devices.
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- Extrusion
- A process by which a material is melted and allowed to
flow through a die to create a desired shape.
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