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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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