Radar
Radio Detection And Ranging
Uses EM energy and high
speed timing circuits to determine distance. Original Radar devices
used energy in the radio frequency range (MHz), many current
devices use much higher frequencies (GHz).
Range
A value related to probe length (factory setting).
Relative Dielectric (
ε
r
)
A unitless number that indicates the relative
permittivity of a material.
Repeatability
The maximum error between two or more
output readings of the same process condition.
RFI
Radio Frequency Interference
Electrical noise that can have an
adverse affect on electrical circuits, particularly low-power devices.
Single Rod Probe
A probe that uses one active rod and a launch
plate (mounting nut, flange, and tank top) to achieve propagation.
This configuration is the least efficient wave-guide, but most forgiv-
ing of coating and buildup.
Span
The difference between the upper and lower limits of the
range.
Specific Gravity (SG)
The ratio of the density of a material to the
density of water at the same conditions.
Sensitivity
The amount of amplification applied to the Level signal;
a higher value aids in measuring low dielectric media; a lower num-
ber assists in ignoring nearby objects.
TDR
Time Domain Reflectometry
Uses a waveguide to carry EM
energy to and from the surface of the media to measure distance;
similar to conventional through-air Radar but much more efficient.
Also called
Guided Wave Radar.
Threshold
Method in which unit chooses correct level signal. CFD
factory default. Select Fixed Threshold when low dielectric material is
over higher dielectric material and unit is reading incorrect level.
Example: oil over water. Adjustment of scale offset may be necessary.
Tick
The smallest digital increment of time utilized in the level
measurement.
Tst Loop
Test Loop
Built-in system capability to test/calibrate a
loop (or separate loop device) by driving the transmitter output to
a particular value.
Trim 4/Trim 20
Built-in system capability to fine tune the 4 mA
and 20 mA points so the transmitter output corresponds exactly to
user’s meter, DCS input, etc.
Twin Rod Probe
A probe that uses two parallel rods to propagate
the EM pulse to the level surface and back. This design is less efficient
and less sensitive than the coaxial probe and is typically used for
higher dielectric media and coating problems.
Two Wire
An electrical instrument design that uses one set of wires
to provide both the supply power and process measurement signal.
The process measurement is achieved by varying the current of the
loop. Also called
Loop-powered.
Units
The engineering units used to measure level in the system.
The choices are in (inches) and cm (centimeters).
Waveguide
See
Probe.
<Window>
A time slice variable that enhances system resolution.
(Factory setting).
Intrinsic Safety
A design or installation approach that limits the
amount of energy that enters a hazardous area to eliminate the poten-
tial of creating an ignition source.
Level
The present reading of the height of material in a vessel.
Linearity
The worst case error calculated as a deviation from a
perfect straight line drawn between two calibration points.
Line-Powered
See Four Wire.
Loop
The present reading of the 4-20 mA current output.
Loop-Powered
See Two Wire.
Low Voltage Directive
A European Community requirement for
electrical safety and related issues of devices using 50–1000 VDC or
75–1500 VAC.
Measured Value
The typical level measurement values used to track
the level of a process: Level, % Output, and Loop.
Medium
The liquid material being measured by the level transmitter.
MIR
Micropower Impulse Radar.
Distance or level measurement
technique that combines Time Domain Reflectometry, Equivalent
Time Sampling, and high speed/low power circuitry.
Multidrop
The ability to install, wire, or communicate with multiple
devices over one cable. Each device is given a unique address and ID.
Non-hazardous Area
An area where no volatile mixtures of
vapors/gas and oxygen will be found at any time.
Also called General
Purpose Area.
Non-incendive
A circuit in which any arc or thermal effect produced
under intended operating conditions of the equipment is incapable,
under specific test conditions, of igniting the flammable gas, vapor,
or dust-air mixture.
Offset
The distance from the bottom of the tank to the bottom of
the probe.
Password
A numerical value between 0 and 255 that protects stored
configuration data from unauthorized manipulation.
Percent (%) Output
The present reading as a fraction of the 16 mA
scale (4–20 mA).
Poll Address (HART ID)
A number between 1 and 15 which sets
an address or location of a device in a multi-drop loop. Poll address
for single device configuration is 0.
Probe
A waveguide that propagates an electromagnetic pulse from
the top of the tank into the process fluid.
Probe Ln
Probe Length
Exact measurement from the bottom
of the process thread connection (where the rod exits the mounting
gland) to the very bottom of the probe.
Prb Model
Probe Model
Particular waveguide configuration or
design. Each probe type is designed to accomplish specific objectives
in an application.
Prb Mount
Probe Mount
The type of process mounting (NPT,
BSP or Flange) utilized in the installation. This aids in establishing
exact zero point for Guided Wave Radar
propagation and measurement.
QuickStart
The essential information needed for the ECLIPSE
transmitter and probe to be installed, wired, and calibrated.
65
57-600 Eclipse
®
Guided Wave Radar Transmitter
